Animal study {zoology}| includes development, tissues, organs, and animal divisions. Animals need light to stimulate vitamin D production, control biological rhythms, and affect pituitary gland. Animals need sodium for nerve and muscle activity.
Large bipedal non-human primate supposedly lives in northwest USA {bigfoot}, Canada {sasquatch}, Asia, Himalaya mountains {abominable snowman}| {yeti} {nyalmot} {rimi} {raksi-bombo}, or Florida swamps.
dead animals {carrion}|.
Animals {denizen}| can live in natural environments, such as deep oceans.
four-legged animals {quadruped}|.
living thing {wight}.
Organisms can have similar forms {homomorphy}|.
Organisms can have same form {isomorphy}|.
In newts and lizards, healed body parts de-differentiate to blastema that can make new tissues {regeneration, biology}|. Animal body-part regeneration has first morphallaxis and then epimorphosis. Dermis and muscle, not bone or epidermis, cells specify positional information. Regeneration happens in quickest way possible.
In lower vertebrates, injured optic-nerve fibers regenerate to same brain target cells. In flatworms, serotonin and dopamine stimulate regeneration by increasing adenylate cyclase activity and altering DNA and RNA synthesis.
In newts and lizards, healed body parts dedifferentiate to form cell clumps {blastema} that can make new tissues.
First, cells make miniature body-part patterns, using chemical signals {morphallaxis}. Whole body, body regions, and localized areas have chemical-signal fields that will determine cell positions. Positioning uses front-back anterior-posterior axis and back-front dorsal-ventral axis.
Second, cells proliferate {epimorphosis}. Farthest {distal} parts grow first, and then nearest {proximal} parts grow.
Differential gene expression can form different cell types {tissue, cell}.
Tissues {adipose tissue}| can hold fat globules. Newborn brown adipose tissue helps stabilize body temperature. White adipose tissue is in abdomen and hips.
Connective tissues {blood tissue} can make cells and plasma. Red blood cells can carry hemoglobin. White blood cells can phagocytize foreign matter.
Specialized epithelial cells {nerve tissue}| can conduct voltage waves along dendrites and axons.
Specialized epithelial cells {reproductive tissue}| can be for sexual reproduction and make non-motile large female egg cells, moving small male sperm cells, and support cells.
Tissues {connective tissue}| {matrix, tissue} {tissue matrix} can support other tissues and secrete intercellular materials. Connective tissues include bone, cartilage, tendon, and fibrous tissue.
Connective tissues can secrete firm, rubber-like matrix {cartilage}| used for shape and light support.
Connective tissue {fibrous tissue}| can be for covering organs and separating organs, by secreting interlocking collagen-fiber network.
Connective tissue {ligament}| can connect organs or bone to bone.
Organs have connective tissue structures {stroma}. For example, cornea middle layer has collagen lamellae.
Connective tissue {tendon}| can connect muscles to each other and to bone.
Fibrous connective tissues {serosa} can lines pericardial, pleural, and peritoneal cavities. They have covering mesothelium.
Hyaluronic-acid cartilage {hyaline cartilage} covers joint bones.
Membranes {septum, membrane} can separate organs or body cavities.
Flat fibrous connective tissue {tarsal plate} shapes eyelid edges.
Connective tissues {bone}| can secrete organic matrix with calcium salts, in layers, which then harden. Some bone cells reabsorb matrix.
Bone has bone cells {fibroblast, bone}|.
Blood vessels and nerves {Haversian canal} go through matrix.
Bone has layers {lamellae}.
Bone centers {marrow, tissue}| have fat {yellow marrow} or regions {red marrow} where red blood cells form.
Continuous body-surface cell layers {epithelial tissue}| include skin, intestinal lining, mucus membrane, and sense tissue.
Inner body-surface epithelia {intestinal lining}| can be for absorption.
Inner body-surface epithelia {mucus membrane}| can be for secretion.
Cylindrical cells {muscular tissue}| can contain contractile actinomycin myofibrils. Muscles can be involuntary or voluntary.
Cardiac and smooth muscles {involuntary muscle}| can contract strongly, slowly, and for long times.
Heart has involuntary muscle {cardiac muscle}.
Involuntary muscles {smooth muscle}| can be in digestive tract and uterus.
Muscles {voluntary muscle}| can contract fast with short contraction time. Only mammals have lateral corticospinal tract, for voluntary-muscle control.
Voluntary muscles {skeletal muscle}| can attach to bones.
Body systems {digestive system}| can eat food, break food into small molecules, absorb them, remove water from unabsorbed food, and pass rest out body. Digestive system has mouth, teeth, pharynx, esophagus, stomach, small intestine, gall bladder, liver, large intestine or colon, rectum, and anus. Digestion processes food, absorbs nutrients, and excretes waste.
Glands {endocrine system}| can secrete hormones into blood using tubes or using diffusion {ductless gland}.
functions
Hormones travel in blood to other organs to trigger internal behaviors and regulate and coordinate body organs.
parts
Endocrine system has pituitary, parathyroid, thyroid, adrenal, hypothalamus, pancreas, ovary, testes, and placenta.
receptors
Hormones bind to cell-membrane receptor proteins. Receptor proteins have three parts: outside receptor, membrane region, and cytoplasm enzymatic region.
signal
Enzymatic region contains tyrosine, to which phosphate can bind and unbind. Cell-signaling molecules have enzymatic regions and non-enzymatic modules {SH2 module} {SH3 module} for binding phosphate to tyrosine and for aligning with receptor-protein enzymatic-region hydrophobic regions.
adapter
SAP and other cell-signaling molecules {adapter molecule} can link several functional domains to involve other enzymes, to coordinate signaling and timing. Adapter molecules make cellular scaffolding to transmit signals.
diseases
Diseases can involve too much or too little signaling. Cancer and X-linked lymphoproliferative (XLP) disease have too much signaling. Immune diseases, type-2 diabetes, HIV, and black-death bacteria (Yersinia pestis) have too little signaling.
Body systems {excreting system}| can remove catabolic products from blood, regulate acidity and water level, and pass catabolites out body. Excreting system has kidney, ureter, bladder, and urethra.
Body systems {integument system}| can cover and protect body. Integument has skin, nails, and hair.
Body systems {muscular system}| can provide force for body-part movements. Muscular system has involuntary and voluntary muscles.
Sense receptors, neurons, sense peripheral nerves, sensory spinal cord, ganglia, brainstem, cerebellum, cerebrum, motor spinal cord, and motor peripheral nerves {nervous system}| have separate peripheral, central, sympathetic, and parasympathetic nervous systems. Nervous system signals, integrates, and regulates body functions. Autonomic nervous system includes sympathetic and parasympathetic nervous systems. All mammals have similar nervous systems.
Body systems {respiratory system}| can put oxygen into blood and take carbon dioxide from blood. Respiratory system has lungs, trachea, larynx, and nose.
Body systems {sensory system}| can respond to stimuli and pass signals to nervous system. Sensory system has eyes, ears, nose, tongue, skin receptors, and ligament and muscle receptors.
Body systems {skeletal system}| can support and shape body, hold organs, and anchor muscles. Skeletal system has bones, cartilage, tendons, ligaments, and fibrous connective tissue.
Body systems {circulatory system} {vascular system}| can transport nutrients and oxygen and remove waste products. Circulatory system has blood vessels, lymph vessels, spleen, and heart.
Body systems {reproductive system}| can produce gametes and provide gamete-union methods. Reproductive system has testes, ovary, fallopian tube, penis, uterus, and vagina. Reproductive systems can produce new individuals from one parent, in asexual reproduction, or two parents, in sexual reproduction.
Animals can lay eggs {oviparous}|.
Some reptiles hatch eggs inside body {ovoviparous}|.
Animals can bear live young {viviparous}|.
Body parts {organ, body} are blood, heart, vessels, brain, nerves, sex organs, lungs, skin, muscles, and glands.
Blood volume is five liters {blood}. Blood flow is five liters per minute.
In capillaries, enzymes {carbonic anhydrase} can convert waste carbon dioxide to carbonic acid, for hemoglobin transport.
Processes {erythropoiesis} can make red blood cells. Erythropoietin makes red-blood cells. Synthetic erythropoietin, epoietin (EPO), can treat anemia.
Centrifuging blood makes cells move to tube bottom, to measure blood-cell percent {hematocrit}|. Male normal is 40% to 50%. Female normal is 36% to 44%. Hematocrit is higher at higher altitudes and with dehydration. Hematocrit is lower in anemia.
Spleen and liver can engulf red blood cells {phagocytize}|.
Red blood cells have agglutinogen antigens and agglutinin antibodies {blood type}|. Blood can have types O, A, B, or AB. If different types mix, they precipitate {agglutination}. Blood can have types M or N. Blood can have Rh factor in 85% of people, or not in 15% of people.
Red blood cells have antigens {agglutinogen} and antibodies {agglutinin}.
Blood groups {ABO blood group} can have type A, type B, type AB, and type O.
gene
Galactosyl transferase gene is on chromosome 9. A and B are co-dominant alleles. O is recessive allele.
diseases
Water-soluble galactosyl transferases can protect people from meningitis, yeast infections, and urinary tract infections but can increase influenza and respiratory synctitial virus. Cholera is highest in type O, middle in A and B, and lowest in AB, so A and B continue to exist {frequency-dependent selection}. Malaria is highest in types A, B, and AB and lowest in type O.
time
Perhaps, Type O is oldest, appearing 50,000 years ago. Perhaps, Type A appeared 25,000 years ago. Perhaps, type B evolved from type O 15,000 years ago. Perhaps, Type AB appeared 1000 years ago.
Blood factors and processes {clotting}| can convert soluble fibrinogen to insoluble fibrin, in three stages.
In first blood-clotting step, platelets attach to disrupted-blood-vessel rough surfaces and disintegrate, aided by protein factors {antihemophilic factor} (AHF) X, VII, XII, XI, IX, VIII, and V, which initiate blood clotting.
Tissue injury releases soluble tissue components {tissue factor} that make thromboplastin enzyme.
Cells release enzymes {thromboplastin}. In second blood-clotting step, thromboplastin, calcium, and factors X, VII, XII, XI, IX, VIII, and V convert thrombinogen to thrombin. Then thrombin converts fibrinogen to fibrin, in four to ten minutes. Heparin and dicumarol prevent making fibrin. Bile deficiency prevents vitamin-K absorption and prevents making fibrin, by decreasing liver proteins.
In third blood-clotting step, blood clots {thrombus} on blood-vessel walls.
People {hemophiliac}| {bleeder} can lack antihemophilic factors and have poor blood clotting.
Proteins {plasmin} can break down blood-clot fibrins and can open clogged arteries. Tissue plasminogen activator (tPA) makes plasmin from plasminogen.
Blood has red-bone-marrow giant-cell fragments {platelet}|, which initiate blood clotting and last four days.
Organs {spleen}| can hold red blood cells. Spleen and liver can phagocytize red blood cells.
Blood fluid {plasma}| can be pale yellow and contain proteins, amino acids, carbohydrates, salts, gases, lipids, and fatty acids. Plasma is 55% of blood.
proteins
Fibrinogen is for blood clotting. Albumin controls osmolarity and binds minerals. Alpha-globulin, beta-globulin, and gamma-globulin are antibodies.
Lipoprotein binds fat. Very-low-density lipoprotein (VLDL) binds cholesterol and triglycerides. Low-density lipoprotein (LDL) binds cholesterol. High-density lipoprotein (HDL) binds nothing.
Apolipoproteins mediate fat transfer to cell receptors. ApoB gene makes apolipoprotein-beta for binding cholesterol. ApoE gene makes apolipoprotein-epsilon for binding triglycerides. ApoA gene and ApoC gene make apolipoproteins. ApoE3 gene binds better than ApoE2 gene or ApoE4 gene, which associate with Alzheimer's disease.
Blood-plasma proteins {albumin, plasma}| can maintain osmotic pressure. Low albumin indicates liver disease or malnutrition.
Fats with polar ends and non-polar ends align in water solution, so non-polar ends are at center and polar ends are on spherical surfaces {micelle}|. Other molecules can be inside.
Plasma {serum}| with precipitated fibrinogen and other clotting factors has no clotting ability.
Disc-shaped cells {red blood cell}| {erythrocyte} contain hemoglobin and have no nucleus.
purpose
Hemoglobin transports oxygen and carbon dioxide.
metabolism
In capillaries, carbonic anhydrase converts carbon dioxide to carbonic acid, for hemoglobin transport. Lungs convert carbonic acid to carbon dioxide and breathe carbon dioxide from body.
amount
Blood-oxygen decrease increases red-blood-cell production. Spleen and liver phagocytize red blood cells. Diarrhea can cause polycythemia.
types
Fetuses have a different hemoglobin type. Sickle cell anemia has red blood cells with curved shapes.
Blood has red cells {corpuscle, cell}|.
Bone marrow has immature red blood cells {reticulocyte}|.
Pale cells {white blood cell}| {leukocyte} can have nuclei and move by amoeboid motion.
Spleen, tonsils, and lymph nodes make leukocytes {lymphocyte}|. Lymphocytes are 25% to 30% of leukocytes.
Spleen and bone marrow make leukocytes {monocyte}|. Monocytes are 5% to 10% of leukocytes.
White blood cells {phagocyte}| can surround and absorb antigens or dead cells.
Red bone marrow makes leukocytes {basophil}, 0.5% of leukocytes.
Red bone marrow makes leukocytes {eosinophil}, 1% to 4% of leukocytes.
Red bone marrow makes leukocytes {neutrophil}, 60% to 70% of leukocytes.
heart and blood vessels {circulation}.
heart {cardiac, heart}|.
heart, arteries, and veins {cardiovascular}|.
arteries and veins {vascular}|.
Most blood-flow resistance {peripheral resistance} is in capillaries.
Blood vessels can grow {angiogenesis}.
Factors {vascular endothelial growth factor} (VEGF) can stimulate angiogenesis and guide blood cells to body regions by finding VEGF receptors. VEGF affects blood-vessel development. Perhaps, blood cells can evolve into blood vessels.
Heartbeats cause artery pressure pushes {pulse, blood}|.
Blood pulses cause pressure {blood pressure}. Blood pressure relates to heartbeat force, blood volume, and arteriole smooth-muscle constriction, which nerves, blood epinephrine, and blood carbon dioxide control. Inelastic and hardened arteries from cholesterol, scars, smoking, and kidney disease make high blood pressure.
Pressure is highest {systole}| {systolic pressure}, 120 mm Hg, when blood pulses.
Pressure is lowest {diastole}| {diastolic pressure}, 75 mm Hg, between pulses.
Arteries and veins have networks {rête}|.
Lymphatic system has a tube {thoracic duct}, from dilation {cisterna chyli} at second lumbar vertebra to left jugular and subclavian veins, that carries lymph into blood.
The first artery {aorta}| is the largest blood vessel.
Blood leaves heart to go into tubes {artery}|. Arteries have inner endothelium-and-elastic-tissue layer, middle smooth-muscle layer, and outer connective-tissue layer.
Blood flow from aorta can go into heart arteries {coronary artery}|.
Arteries have branches {arteriole}|.
Blood flows from arteries into tubes {capillary}|, where molecules diffuse between blood and tissue fluids. Capillaries have endothelial cell layers. Most peripheral resistance to blood flow is in capillaries.
Head has neck arteries {carotid artery}| on sides.
Head has arteries {vertebral artery} beside spine.
Vein system has structure {venation}.
about veins {venous}.
From capillaries, blood goes into tubes {vein, circulation}| that have same layers as arteries but with thinner muscle layers. Valves prevent backward flow.
The first veins {venule} are small tubes.
Veins {saphenous vein}| drain leg surfaces.
Swollen veins {varicose vein}| can be in legs.
Veins {hepatic portal system}| can collect blood from spleen, stomach, pancreas, and intestines and take blood to liver.
Blood reaches largest veins {vena cava}| to enter heart, from above {superior vena cava} and below {inferior vena cava}.
Head has side neck veins {jugular vein}|.
Head has neck veins {vertebral vein} by spine.
Blood pumping organs {heart}| have auricles and ventricles. Skeletal muscles and breathing assist blood movement. Heart volume increases with regular exercise.
Heart cavity has inside endothelium {pericardium}|.
Blood goes from vena cava into heart chamber {right atrium} {auricle}| {atrium, heart} at heart top right.
Right atrium pumps blood through valve {tricuspid valve}| to right ventricle.
Right atrium pumps blood through tricuspid valve to lower right chamber {right ventricle} {ventricle, heart}|.
Right ventricle pumps blood through valve {semilunar valve}| into pulmonary artery.
Right ventricle pumps blood through semilunar valve into lung artery {pulmonary artery}|.
Blood goes from pulmonary artery to lung capillaries and then to lung vein {pulmonary vein}| back to left atrium.
Left atrium pumps blood through valve {bicuspid valve}| into left ventricle.
Left ventricle pumps blood through valve {mitral valve}| into aorta. Mitral valve gives high and short sound. Other valves and ventricle closures give low and long sound. Heart-sound change indicates valve damage. Syphilis and rheumatic fever weaken heart valves.
Signals from specialized heart tissue {sinoatrial node} {pacemaker} initiate and regulate heartbeat. Heart fibers beat by themselves. Blood carbon dioxide, blood thyroxin, blood epinephrine, vagus-nerve stimulation, body temperature, fever, and muscle stretching affect heart rate.
Signals go from sinoatrial node to specialized heart tissue {atrioventricular node} and then to ventricles.
Digestion organs {digestion} include mouth, throat, stomach, and intestines.
intestinal {enteric}| bacteria or waste.
Pharynx has a reflex {swallowing reflex} to swallow. Swallowing reflex closes off nasal cavity and larynx and opens esophagus.
Opening esophagus stimulates circular contraction waves down esophagus {peristalsis}|, to carry bolus to stomach. Peristalsis can cause throat spasm {lump in the throat}.
Body linings secrete fluid {mucous}|.
Mouth mucous {saliva}| contains many proteins. Histatins, lactoferrin, lyzozyme, and peroxidase can break up bacteria and yeast. Mucins make sticky coverings to coat teeth and gums. Proline-rich proteins hold calcium phosphate for tooth enamel. Amylase changes starches into sugars. Epidermal growth factor makes more cells. Proteins {SLPI protein} {slippy protein} can aid wound healing.
spit {sputum}.
The first breast milk {colostrum}| is thin but has nutrients and antibodies. It flows until several days after birth.
Ruminants regurgitate stomach contents and chew them again {cud}|.
Rectum distension stimulates defecation of residues {feces}|.
Rectum distension stimulates feces excretion {defecation}|.
bird feces on ground {dropping}.
mammal feces on ground {dung}.
Feces can be fertilizer {manure}.
feces {offal}.
feces {spoor}.
Body openings {orifice}| are at mouth and anus.
Space {perineum}| between vagina and rectum has muscle and other tissue.
lower trunk above hips {abdomen, human}.
large intestine {bowel}|.
abdomen {breadbasket}.
intestines {entrails}.
Mouth, esophagus, stomach, and intestines form a tube {gastrointestinal tract}| {GI tract}.
intestines {viscera}|.
Body has organs {vitals} necessary for life, such as heart, lungs, and brain.
Digestive organs have outermost connective-tissue coverings {adventitia}.
Fibrous connective tissue {fascia, tissue} surrounds organ or body cavity.
Digestive organs have tissue {parenchyma}, not including coverings and supports.
First, lips and mouth {mouth, body}| receive food.
mouth {maw}.
A muscular appendage {tongue muscle}| attached to mouth back has taste buds, pushes food onto teeth, and rolls food into boluses.
Tongue muscle pushes food onto teeth and rolls food into balls {bolus}. Muscles push bolus into pharynx.
Organs {pharynx}| after mouth receive Eustachian tubes and have swallowing reflexes.
Mouth roof {palate}| is hard in front and soft in back.
Palate front {hard palate}| has bone covered by mucosa.
Palate back {soft palate}| {velum} has connective tissue and muscle. Soft palate can close opening to nasal cavity while swallowing.
Soft palate has one cone {uvula}| hanging down, which can swell, causing snoring.
At throat back are two ovoid lymph-tissue regions {tonsil}|.
After pharynx, one tube {esophagus}| goes to stomach. Opening esophagus stimulates peristalsis down esophagus, to carry bolus to stomach.
Mouth glands {salivary gland}| secrete watery or mucous saliva, to hydrolyze starch to dextrins or glucose and to moisten food.
Salivary glands {parotid gland} can be near ear fronts.
Salivary glands {sublingual gland} can be under tongue.
Salivary glands {submaxillary gland} can be near jaw angle.
Mouth cutting, grinding, and chewing units {teeth, mouth}| can have roots, cementum, necks, gums, and crowns. Teeth are incisors, cuspids, bicuspids, and molars.
String {dental floss} can remove debris and bacteria from teeth.
toothpaste {dentifrice}.
People gain teeth sets {dentition} in sequence.
People can need replacement teeth {denture}|.
Upper teeth can not align with lower teeth {malocclusion}.
Front tooth can stick out {bucktooth}|.
Bacteria can form tooth film {calculus, teeth}|.
Bacteria can dissolve tooth enamel {cavity, teeth}|.
Bacteria can make layers {tartar}| on teeth.
Bacteria can dissolve tooth enamel {tooth decay}.
People have eight front teeth {incisor}|.
People have four cone-shaped teeth {canine teeth} {cuspid}|.
One pointed canine tooth {eyetooth}| is between incisor and premolar.
People have eight flattened two-pointed small teeth {pre-molar} {bicuspid}|.
People have twelve large flat teeth {molar, tooth}|. The first molars are six-year molars, behind baby teeth.
The last four molars {wisdom teeth}| {third molars} can be missing or embedded. Wisdom teeth appear at 17 to 21 years old.
People replace baby teeth with new sets {permanent tooth}|. People have 32 permanent teeth.
Children have first teeth sets {baby tooth}|. The 20 baby teeth include 8 incisors, 4 cuspids, and 8 bicuspids.
baby tooth {milk teeth}.
Teeth have parts {root, teeth} in jawbones, held with cementum.
Teeth roots are held in jawbone with glue {cementum}.
Teeth have inner layers {mesenchyme} with nerves.
Inner tooth {dental pulp} {pulp, teeth} has blood vessels and nerves.
Gums surround teeth bottoms {neck, teeth}.
Teeth necks are in flesh {gum, teeth}|.
Under enamel and in root is bone-like material {dentin} {dentyne}.
Teeth have parts {crown, teeth} above gums. Grass eaters have crowns that go below gums {hypsodonty}. Leaf eaters have crowns only over top.
Crowns have hard, smooth, and white layers {enamel, teeth}.
A muscular sac {stomach}| on trunk left side receives food from esophagus. Stomachs have region {cardiac region} near heart, large sac {fundus, stomach}, and pylorus. Stomachs have a smooth-muscle-ring sphincter at top opening, which closes after bolus enters. Stomach and digestive tract have inner mucosa, middle circular and longitudinal muscle layers, and outer connective-tissue layer. Stomachs hold 2.5 liters. Stomachs can absorb alcohol, aspirin, and poisons. Helicobacter pylori bacteria cause stomach ulcers.
Birds and primitive mammals have stomachs {craw}| that store and break down food.
Peristalsis churns food to soup {chyme}. Chyme passes through sphincter to small intestine.
Stomach glands {gastric gland} secrete hydrochloric acid and proteolytic enzymes. Gastrin hormone controls stomach secretions.
Stomach and digestive tract have inner mucous membrane {mucosa}|.
Stomachs have a region {pylorus}| near small intestine.
Brain controls ability to eject stomach contents {vomiting reflex}|.
After stomach comes small and then large intestine {intestine}|. Gut distension causes pain but squeezing, cutting, or burning does not cause pain.
Intestines have inside spaces {lumen, intestine}|.
After stomach is one folded tube {small intestine}|, 30 feet long, which absorbs almost all food materials. End sphincter allows material to pass to colon. Intestinal wall secretes enzymes to break up proteins. Glucose and amino acids have active transport into blood. Lymph absorbs fats. Small intestine has peristalsis and churning movements.
Food passes through small intestine eight hours {transit time}.
Small-intestine mucosa has many cytoplasm fingers {villus}, to absorb sugars and salts.
Small intestine attaches to body back wall by connective tissue {mesentery}|.
Fat and connective tissue {omentum}| are in front of intestines.
Connective-tissue membrane {peritoneum}| lines intestines and body cavity holding intestines.
Peritoneum can have bacterial infections {peritonitis}|.
Small intestine has first part {duodenum}|.
Small intestine has second short part {jejunum}|.
Small intestine has long part {ileum}|.
A large gland {liver, organ}| on middle right side secretes bile salts into small intestine. Liver stores and converts sugars and carbohydrates, receives amino acids and sugars from intestine via portal vein, makes urea, synthesizes plasma proteins, stores vitamins, detoxifies alcohol and ketones, and regulates and produces lipids and fatty acids.
Bladders {gall bladder}| under liver hold liver bile salts and release bile salts into duodenum, to break up fats and neutralize stomach acid. Secretin hormone can control bile stimulation. Precipitated-cholesterol gallstones can be in bile ducts.
Gall bladders hold liver bile salts {bile}|. In duodenum, bile salts break up fats and neutralize stomach acid.
Hemoglobin breakdown products {bile pigment} can accumulate in jaundice.
Under stomach, one gland {pancreas}| secretes enzymes {pancreatic juice} into duodenum, to break up proteins. Secretin controls pancreas.
Pancreas cells {islets of Langerhans} {Langerhans islets} can secrete insulin and glucagon into blood.
After small intestine, wider intestine {colon, intestine}| {large intestine} curves up right side, across body-wall back, and then down left side. Colon removes water and has peristalsis and churning movements. Colon has 12-hour to 24-hour transit time.
colon beginning {cecum}|.
Cecum has a small tube {appendix, intestine}| at bottom.
Colon ends {sigmoid colon}| are holding regions.
A muscular tube {rectum}| connects to anus. Rectum distension stimulates defecation.
Rectum has an end sphincter {anus}|.
Human proteins from secreting organs {endocrine gland}| can affect remote cells. Hormones can help growth. Neurohormones can control neuron and glia division, migration, and maturation.
Cells {chromaffin cell} receive cholinergic neurons.
The 28-day female-hormone cycle {menstrual cycle}| has high estrogen for 21 days and high progesterone for 7 days, with estrogen increasing until day 12 after menstruation and then progesterone increasing until day 21. Luteinizing hormone and follicle-stimulating hormone maximize at 14 days.
Egg release {ovulation}| is at menstruation-cycle day 14, when luteinizing hormone and follicle stimulating hormone peak.
Endocrine-gland growth-control proteins can affect same cells {autocrine}. For example, neurohormones can control neuron and glia division, migration, and maturation.
Glands {exocrine gland} can send chemicals out tubes.
Endocrine-gland growth-control proteins {paracrine} can affect nearby cells. For example, neurohormones can control neuron and glia division, migration, and maturation.
Organs {gland, organ}| can secrete chemicals.
Glands {adrenal gland}| above kidneys can secrete adrenalin.
Small hypothalamus region {pituitary} {hypophysis}| regulates autonomic functions, including growth hormones.
Posterior pituitary has gland-like neuron regions {neurohypophysis}.
Glands {hypothalamus, gland} can secrete brain hormones.
Intestinal walls {gland, intestine} {intestinal wall gland} {intestine gland} can make secretin hormone for protein digestion and cholecystokinin hormone for fat digestion.
Female peritoneum glands {ovary, gland} can make female hormones and eggs. The 28-day female-hormone menstrual cycle has high estrogen for 21 days and high progesterone for 7 days, with estrogen increasing until day 12 after menstruation and then progesterone increasing until day 21. Egg ovulation is at day 14, when luteinizing hormone and follicle stimulating hormone peak.
A gland {pancreas gland} below stomach can affect digestion and blood sugars, by making insulin and glucagon.
Small glands {parathyroid gland}| on thyroid glands can make calcium-regulation hormones.
An epithalamus gland {pineal gland}| can control circadian rhythms. In most animals, pineal gland receives light from retina. In species with third eyes, pineal gland receives from third eye. Light on pineal gland releases melatonin into blood. Pineal N-acetyltransferases act like biological clocks. Pit vipers combine infrared system with other sense modes.
Pineal prevents pituitary from secreting gonadotrophic hormones. After pineal control relaxes, adolescence starts.
A male scrotum gland {testis, gland} can make male sexual hormones and sperm.
Throat glands {thymus gland}| can make antibodies in infants but have no adult function.
Throat glands {thyroid gland}| can make thyroxin hormone.
Molecules {corticotropin releasing factor} (CRF) can release corticotrophin, vasopressin, and angiotensin II, using negative feedback. CRF causes insomnia, low appetite, low sex drive, depression, and anxiety. CRF affects hypothalamus but not enkephalin and neurotensin release.
Phosphate bonds between adenine-pentose-sugar fifth carbons and third carbons make rings {cyclic AMP}| (cAMP).
purpose
Cyclic AMP transfers one phosphate group for phosphorylation. cAMP increases active transport, degrades stored fats, uses tissue carbohydrates, increases stomach hydrochloric acid, disperses melanin, and stops platelet aggregation. cAMP mediates cell processes that increase vesicle mobility, membrane fusion, and release and cause chemotaxis, morphogenesis, and gene expression.
process: hormones
Hormones that use cAMP include calcitonin, chorionic gonadotropin, epinephrine, follicle-stimulating hormone, glucagon, luteinizing hormone, melanin-stimulating hormone, norepinephrine, parathyroid hormone, thyroid-stimulating hormone, vasopressin, corticotropin, and lipotropin. Hormone attaches to cell-membrane receptors that are similar to beta-adrenergic catecholamine receptors.
process
Receptors couple to G proteins and adenylate cyclase. Receptors activate membrane G protein by phosphorylation and make many cyclic AMPs. cAMP activates protein kinases, which phosphorylate other enzymes. cAMP amplifies hormone effect 100 times.
bacteria
In E. coli, cAMP stimulates flagellin synthesis, cell motility, and food-seeking behavior. E. coli protein starvation increases cAMP.
plants
cAMP regulates light-induced growth responses in giant single-celled fungus Phycomyces sporangiophore, in which dopamine and epinephrine stimulate adenylate cyclase.
protozoa
In unicellular organisms, cAMP is sensitive to catecholamines. In Tetrahymena pyriformis protozoa, cAMP regulates cell growth and glucose metabolism, as epinephrine and serotonin excite adenylate cyclase.
amoeba
Starvation causes cAMP release by myxamoebas.
fruitfly
Fruitfly learning mutants have bad cyclic-AMP or cyclic-AMP-receptor genes.
Human proteins {growth factor} can control growth.
Hypothalamus thyroid-hormone releasing factor (THRF), luteinizing-hormone releasing factor (LHRF), and somatostatin growth-hormone release-inhibiting factor {hypothalamic hormones} release hormones from anterior pituitary gland.
Posterior-pituitary-gland neurohypophysis hormones {vasopressin}| can constrict artery smooth muscle and so cause kidney to conserve fluid {antidiuretic hormone, vasopressin}, affect pair-bonding in male rodents, and consolidate memories. It affects locus coeruleus and can cause memory to be unforgettable. Vasopressin and oxytocin are similar. Vasopressin can treat shock from low blood pressure.
Liver and fat enzymes {11 beta HSD-1} can activate cortisol and make more triglycerides.
Fat cell hormones {adiponectin} can affect insulin and lipid metabolism.
Receptors {cannabis receptor} {CB1 receptor} that bind cannabis can stimulate appetite.
Liver proteins {FGF21 protein} can metabolize fat.
Gut peptides {ghrelin} can stimulate arcuate-nucleus appetite region.
Two hypothalamus peptides {orexin} {hypocretin}| can come from preprohypocretin and bind to lateral-hypothalamus receptors. They increase appetite and cause arousal. Hypocretin mutations can cause mammalian narcolepsy. Normal hypocretin is in Golgi organs, and mutated hypocretin is in smooth endoplasmic reticulum.
Fat-cell molecules {leptin}| can bind to hypothalamus receptors and suppress appetite. Leptin decreases arousal. Leptin stimulates satiation region and inhibits arcuate-nucleus appetite region.
Hormones {obestatin} can suppress appetite.
Fat-cell hormones {retinol-binding protein 4} can inhibit insulin receptors.
Cells release proteins {uncoupling protein 1} to ask for energy. Stimulating beta3-adrenergic and PPAR-nuclear receptors increases uncoupling protein 1 release.
Circulating hormones {calcitonin}| can regulate calcium.
Hormones {parathormone}| can liberate calcium from bone.
Anterior-pituitary hormones {growth hormone}| (GH) can increase bone, increase body growth, raise metabolism rate, and make glucose from glycogen. Growth hormones enter cells directly and bind to cytoplasm receptors, which send molecules to cell nucleus to bind to DNA sites and express or repress genes. Growth hormone helps generate and maintain nerve-pathway connections.
Hormones {trophic hormone} can generate and maintain nerve-pathway connections.
Anterior-pituitary hormones {thyrotropin}| can increase thyroid growth and thyroxin production.
Hypothalamus and anterior-pituitary hormones {thyrotropin-releasing hormone}| (TRH) can act locally to release thyrotropin. Small quantities induce euphoric states and can be antidepressants for treating affective disorders. Medulla-oblongata hormones can release hypothalamus thyrotropin.
Thyroid hormones {thyroxin}| can increase basal metabolism rate. Thyroxin requires iodine.
Hormones {adrenal corticoid hormone}| can regulate kidney Na+ and K+ reabsorption.
Kidney hormones {aldosterone}| can control blood pressure.
Hormones {antidiuretic hormone, endocrine}| (ADH) can increase kidney water reabsorption and so block water loss.
Mammal hypothalamus supraoptic and paraventricular nuclei synthesize octapeptides or nonapeptides {arginine vasopressin}| (AVP).
functions
AVP regulates water balance. Decreased blood volume or increased plasma osmotic pressure causes AVP secretion. AVP causes blood-vessel constriction, maintaining blood pressure in cases of decreased blood volume. AVP stimulates intestinal motility, lowering fluid loss. AVP increases cell permeability to water in kidney collecting tubules. AVP enhances sodium-chloride active transport in renal medullary tubules.
AVP secretes in pain and stress. AVP stimulates adrenocorticotropic hormone release, triggering adrenal steroid secretions and stress responses.
AVP can affect mammal pair bonding and infant care.
receptors
AVP binds to kidney-tubule, vascular smooth-muscle, pituitary, and intestinal cell receptors.
receptors: baroreceptor
Reduced blood volume decreases blood pressure and stimulates low-pressure stretch baroreceptors in left atrium, aorta, and carotid. Baroreceptors stimulate glossopharyngeal and vagus nerves to hypothalamus, which liberates AVP from pituitary nerve terminals.
receptors: osmoreceptor
Increased plasma concentration and higher osmolality stimulate osmoreceptors in hypothalamus, resulting in AVP secretion.
Hormones {mineralcorticoid} can regulate salts.
Hormones {posterior pituitary neurohormone} can act directly on kidneys, to decrease urine formation and water loss.
Hormones {prodynorphin} can act on posterior pituitary hormones, to control blood volume and regulate blood pressure.
Neurons {sympathetic nervous system, hormones} can express leucine-enkephalin, methionine-enkephalin, adenosine, neuropeptide Y, cholecystokinin, luteinizing-hormone releasing hormone (LHRH), VIP, and vasopressin-like molecules.
Atrial glands secrete A and B peptides, which depolarize abdominal-ganglion electrically coupled neurons {bag cell}. Bag cells secrete peptides, including egg-laying hormones, into blood to affect central neurons and ovotestis.
Enzymes {catechol-O-methyltransferase} (COMT) can inactivate catecholamines.
Hormones {epidermal growth factor}| (EGF) can support brain-cortex neurogenesis. Cell-membrane outsides have EGF receptors. EGF binding stimulates cell growth and division. Cancer cells have many EGF receptors.
Hormones {fibroblast growth factor}| (FGF) can support cerebral-cortex neurons, especially striate-cortex neurons. At high concentrations, FGF enhances neurogenesis. At low concentrations, FGF increases neuron and glia survival rates. Fibroblast growth factor 8 organizes cortex. Human genes {fibroblast-growth-factor receptor L1 gene} (FGFRL1 gene) can be similar to flatworm genes {nou-darake gene} {Ndk gene} that repress neuron division.
Hormones {microphthalmia-associated transcription factor} (MITF) can regulate eye development, blood-cell development, and skin pigments.
Cyclized 20-carbon unsaturated fatty acids {prostaglandin}|, with two carbon-chain tails, come from all tissues, derive from fatty acids, have over 14 varieties, lower blood pressure, make smooth muscles contract, and block hormones.
types
Prostaglandins can degenerate corpus luteum and regulate activities induced by hormones. Prostaglandin E1 affects inflammation, contracts smooth muscles, stops stomach hydrochloric-acid production, opens bronchi, stops fat breakdown, constricts pupils, relaxes blood vessels, and reduces blood pressure. Prostaglandin I2 inhibits platelet clumping and prevents arterial-lining damage. Endoperoxides regulate cyclic-AMP metabolism and are prostaglandin intermediates.
comparison
Aspirin, arthritic drugs, and anti-inflammatory drugs are similar to prostaglandins.
polarity
Prostaglandins change polarization over the long term.
metabolism
Enzymes {prostaglandin synthetase} can catalyze arachidonic-acid oxidation to prostaglandin H2. Enzymes {prostaglandin hydroperoxidase} can oxidize xenobiotics. Cyclooxygenase-2 and other cyclooxygenases (COX) can generate prostaglandin. Aspirin, ibuprofen, rofecoxib, and non-steroidal anti-inflammatory drug inhibit cyclooxygenases.
Molecules {scotophobin} can make animals afraid of the dark.
Brain, cerebrospinal-fluid, and cerebral-blood peptides {sleep peptide}| can induce sleep.
Brain and gut peptides {bombesin} can lower body temperature, control gastric secretions, and stimulate appetite.
Intestinal hormones {peptide YY3-36} (PYY) can work in hypothalamus to reduce appetite.
Gut, hypothalamus, medulla-oblongata, pons, substantia-nigra, and spinal-cord dorsal-root peptides {substance P}| (SP) can be in fine pain fibers and affect peripheral sympathetic catecholamine neurons. Substance P releases serotonin from terminals inhibited by serotonin. Substance P makes long lasting excitation by slow, excitatory postsynaptic potentials and can cause pain. Substance P increases preprotachykinin mRNA. Sympathetic-neuron activity suppresses substance P. Serotonin enhances substance-P release to excite spinal cord.
Gut, cerebral-cortex bipolar-cell, and submandibular salivary-gland postsynaptic parasympathetic-neuron peptides {vasoactive intestinal peptide}| (VIP) can regulate neuronal mitosis, process outgrowth, and sympathetic-neuron survival.
Three genetically different peptide families {endorphin}| include proopiomelanocortin (POMC), proenkephalins, and prodynorphin. One large exon encodes peptides derived from proenkephalin and POMC, so this gene encodes related behaviors.
locations
Pituitary-gland intermediated lobe and anterior lobe synthesize POMC. Cortex, spinal-cord neurons, adrenal medulla, and gut make proenkephalins. Gut, posterior pituitary, hypothalamus, basal ganglia, and brainstem make prodynorphin.
types
Alpha-endorphin soothes. Beta-endorphin causes analgesia. Gamma-endorphin irritates.
biology
Endorphins are neurohormones or neurotransmitters. Endorphins bind to opiate receptors to inhibit pain-information transmission and cause analgesia. Peripheral pain-receptor stimulation thresholds increase, and central pain perception becomes less sensitive. CREB regulates endorphin production.
Pituitary hormones {encephalin} {enkephalin}| can have five-amino-acid opioid cores, bind to morphine-binding sites, and inhibit pain-information transmission. Enkephalins can acetylate, amidate, phosphorylate, glycosylate, and methylate. Methionine-enkephalin and leucine-enkephalin are peptides, act as opioids, and are in area postrema, locus coeruleus, medulla oblongata, pons, retina, superior olive, spinal cord, and ventral pallidum. Methionine-enkephalins are beta-endorphin precursors. Leucine-enkephalins are dynorphin precursors.
functions
Sympathetic-nervous-system enkephalins control blood vessels, regulate local blood flow and pressure, and cause analgesia.
Basal-ganglia, hypothalamus, pituitary-gland, and adrenal-gland peptides {opiate peptide}| {opioid peptide} can act as analgesics when in cerebrospinal fluid. Repeated stressful stimuli release opioids. Basal ganglia opiate peptides include dynorphin, beta-endorphin, met-enkephalin, leu-enkephelin, and kyotorphin. Bony fish and higher animals have opiate systems.
Hormones {proenkephalin} can act on posterior pituitary hormones, to control blood volume and regulate blood pressure. Cortex neurons, spinal-cord neurons, adrenal medulla, and gut make proenkephalins.
Anterior pituitary, mediobasal hypothalamus arcuate nucleus, and solitary-tract nucleus make opiate peptides {proopiomelanocortin} (POMC). POMC releases ACTH, endorphins, and melanocyte-stimulating hormones. POMC influences adrenal cortex and blood pressure.
Medulla oblongata, solitary tract nucleus, and adrenal-gland medulla release biogenic amines {adrenaline} {adrenalin} {epinephrine}| that can inhibit or excite neuron metabolism for seconds.
biology
Epinephrine stimulates sympathetic nervous system and increases heart activity and muscular action. It releases glucose from liver and makes glucose from glycogen. It increases heart rate and constricts most blood vessels but dilates coronary and skeletal muscle arteries. It dilates bronchi, relaxes smooth muscle, contracts sphincters, and contracts spleen.
causes
Stress, fear, and flight-or-fight response release epinephrine.
norepinephrine
Norepinephrine reacts similarly.
Adrenal-gland medulla, lateral tegmentum, locus coeruleus, medulla oblongata, and sympathetic neurons release biogenic amines {norepinephrine}| {noradrenaline} {noradrenalin} that can inhibit or excite neuron metabolism for seconds.
biology
Norepinephrine stimulates sympathetic nervous system and increases heart activity and muscular action. It releases glucose from liver and makes glucose from glycogen. It increases heart rate and constricts most blood vessels but dilates coronary and skeletal muscle arteries. It dilates bronchi, relaxes smooth muscles, contracts sphincters, and contracts spleen.
causes
Stress, fear, and flight-or-fight response release norepinephrine.
epinephrine
Epinephrine reacts similarly.
Testis and adrenal cortex make dehydroepiandrosterone, androstenone, and testosterone {androgen}|, which cause male sex characteristics. Androstenones can be pheromones. Androstadienone has odor, detected by receptors {OR7D4 receptor}.
Placenta hormones {chorionic gonadotropin}| can maintain pregnancy.
Neuropeptides {egg-laying hormone} (ELH) can regulate sea-snail egg laying. Atrial glands secrete A and B peptides, which depolarize bag cells. Bag cells secrete multiple peptides, including egg-laying hormones, into blood to affect central neurons and ovotestis.
Estrone and estradiol {estrogen}| are from adrenal cortex, are steroids, and stimulate growth and female sex characteristics. Estrogens enter cells directly and bind to cytoplasm receptors, which send molecules to cell nucleus to bind to DNA sites and express or repress genes.
Anterior pituitary hormones {follicle stimulating hormone}| (FSH) can stimulate Graafian-follicle and seminiferous-tubule growth. FSH first secretes at age 7 to 8 and reaches adult levels at age 11 to 13.
Hormones {lutein hormone releasing factor} {luteinizing-hormone-releasing hormone} (LHRH) can bind to forebrain and hypothalamus, release luteinizing hormone in hypothalamus, help sexual arousal and mating, stimulate sex drive, and cure oligospermy.
Pituitary hormones {luteinizing hormone}| (LH) {interstitial cell-stimulating hormone} (ICSH) can control progesterone or testosterone production and release, which first secretes at age 7 to 8 and reaches adult levels at age 11 to 13.
Hypothalamus peptides {oxytocin}| (Vincent du Vigneaud) [1953] can have nine amino acids, control uterus contraction, affect pair-bonding in female rodents and nursing babies, control milk release, peak at orgasm {cuddle hormone}, and aid forgetting. Oxytocin receptors are in hypothalamus, amygdala, nucleus accumbens, and anterior-cingulate subgenual area. Pitocin is synthetic oxytocin. Vasopressin and oxytocin are similar.
Ovary hormones {progesterone}| can regulate estrous and menstrual cycles. Progesterone enters cells directly and binds to cytoplasm receptors, which send molecules to cell nucleus to bind to DNA sites and express or repress genes.
Pituitary hormones {prolactin}| can maintain estrogen and progesterone secretion, stimulate milk production, and control maternal instincts.
Ovary and placenta hormones {relaxin}| can relax pelvic ligaments for birth.
Adrenal-cortex and testes hormones {testosterone}| can stimulate growth and male sex characteristics. Testosterone enters cells directly and binds to cytoplasm receptors, which send molecules to cell nucleus to bind to DNA sites and express or repress genes.
Fish have molecules {vasotocin} that reduce ovulating-female fear of males. In mammals, vasotocin has evolved to oxytocin and arginine vasopressin.
Hormones {gamma-melanocyte stimulating hormone}| (gamma-MSH) can aid steroid production.
Pituitary intermediate-lobe hormones {intermedin}| can stimulate skin pigments.
Anterior-pituitary hormones {alpha melanocyte stimulating hormone} {alpha MSH} {melanin stimulating hormone}| {melanocyte stimulating hormone} (MSH) can aid attention and darken skin by increasing melanocyte pigment production.
Anterior-pituitary hormones {adrenocorticotropin}| (ACTH) {corticotropin} can stimulate adrenocortical cells to synthesize and release glucocorticoid hormones and so make glucose from glycogen, control corticosteroid production, aid attention, and cause cortex analgesia at non-opiate receptors. ACTH amino acids four to seven make short-term memory permanent.
Cortisol and cortisone {corticosteroid}| are from adrenal cortex, convert proteins to carbohydrates, prevent inflammation, increase metabolism rate, increase glycogen storage in liver, darken skin, and stimulate milk production. CYP17 gene modifies cholesterol to make cortisol. Cortisol suppresses lymphocyte interleukin-2 activity. Long-term stress increases cortisol. Adrenal-cortex aldosterone, corticosterone, and deoxycorticosterone regulate sodium and potassium metabolism.
Hormones {glucagon}| can increase liver glucose concentration, decrease liver glycogen production, and decrease other-cell glucose.
Hormones {glucocorticosteroid}| can regulate sugar and protein.
Hormones {insulin, hormone}| can decrease liver glucose concentration, increase liver glycogen production, and increase other-cell glucose. Insulin-like growth factors (IGF) regulate neuron-process growth and mitosis.
Blood flows to kidney, in middle-trunk back wall, where filtration removes waste products {excretion, kidney}.
Kidneys have adjacent nephrons, in which water flows in opposite directions {countercurrent mechanism}|, that exchange water to regulate blood acidity, blood salt concentrations, blood volume, and total body water.
processing
First, in kidney cortex, blood pressure forces urea, creatinine, uric acid, ammonia, ions, and water to diffuse through capillary membranes into Bowman's capsule.
Below Bowman's capsule, nephron convolutes, and active-transport reabsorption returns glucose, amino acids, and salts from proximal convoluted tubule to blood, along with water.
Proximal convoluted tubule then goes down into kidney medulla, becomes loop of Henle, turns around, and comes back up to kidney cortex.
Loop then convolutes and becomes distal convoluted tubule, which secretes non-diffusible waste substances from blood into urine in augmentation.
Distal convoluted tubule then goes into kidney medulla, becomes collecting tubule, which is adjacent to loop of Henle, and absorbs or desorbs water to regulate blood and urine water concentrations.
countercurrent
Loop of Henle and collecting tubule form a countercurrent structure. See Figure 1.
The first downward loop-of-Henle part contains liquid that has received blood waste and nutrients, in Bowman's capsule, and returned nutrients and water to blood, in proximal convoluted tubule. It has moderate waste concentration and low nutrient concentration. Collecting tubule has received waste from blood that cannot diffuse out. If collecting tubule has too little water and downward loop has too much water, downward loop diffuses water to collecting tubule, causing upward loop to receive moderate water from downward loop and send it into collecting tubule. If collecting tubule has too much water and downward loop has too little water, collecting tubule diffuses water to downward loop, causing upward loop to receive moderate water from downward loop and send it into collecting tubule.
The second upward loop-of-Henle part can diffuse water into, or receive diffuse water from, downward loop and collecting tubule to exactly balance water concentrations.
Water typically flows from loop of Henle into collecting tubule, because collecting tubule has high waste concentrations and therefore has low water concentration. Loop of Henle has low diffusible-waste concentrations, has no non-diffusible wastes, and has higher water concentration, as blood excretes water into Bowman's capsule.
changes
If you drink water, blood water increases and blood pressure increases. Blood puts much water into Bowman's capsule with little waste and nutrients. Proximal convoluted tubule puts water and most nutrients back into blood. Loop of Henle carries water to distal convoluted tubule, where urine receives little non-diffusible waste. Collecting tubule has almost same concentrations as loop of Henle, so little water diffuses. Extra water in your body then excretes.
If you do not drink enough water, blood water decreases and blood pressure decreases. Blood puts little water into Bowman's capsule, with high waste and nutrient concentrations. Proximal convoluted tubule puts all water and nutrients back into blood. Loop of Henle carries little water but high waste concentration to distal convoluted tubule, where urine receives little non-diffusible waste. Collecting tubule has almost same concentrations as loop of Henle, so water diffuses back into loop of Henle. Little water excretes.
pressure
Water-diffusion countercurrent process determines water, salt-ion, and hydrogen-ion concentrations at downward-loop top and so in proximal convoluted tubule. The liquid at proximal-convoluted-tubule end can put more or less back pressure on proximal-convoluted-tubule liquid, which then diffuses more or less water back into blood, controlling blood volume and total body water.
The liquid at proximal-convoluted-tubule end can have higher or lower salt-ion concentrations, which push more or less salt ion back into blood, controlling blood salt. The liquid at proximal-convoluted-tubule end can have higher or lower hydrogen-ion concentration, which pushes more or less hydrogen ion back into blood, controlling blood acidity.
Bladder distension stimulates contraction, and urine flows through urethra to outside {urination, excretion}|.
Kidneys secrete fluid {urine}| with ions and urea. Hemoglobin breakdown products cause urine color.
Renal pelvis becomes a muscular tube {ureter} to bladder. Urine moves by peristalsis.
Bladder distension stimulates contraction, and urine flows through a tube {urethra}| to outside.
kidney {renal}|.
Excretory system has organs {kidney}| in middle-trunk back wall. Kidney regulates blood pH, blood salt, blood volume, and total body water. Increasing blood water increases blood pressure. Increasing blood pressure increases water filtration into kidney, reducing water in blood and reducing blood pressure. Kidney problems can cause edema. Kidney makes aldosterone, which controls blood pressure.
Kidneys have outer layers {cortex, kidney}.
Kidneys have inner layers {medulla, kidney}.
In kidney cortex, blood capillaries {glomerulus, kidney} {glomeruli, kidney} surround nephrons.
In kidney cortex, glomeruli surround small tubules {nephron}.
In kidney cortex, sacs {Bowman's capsule} {Bowman capsule} surround capillaries. Urea, creatinine, uric acid, ammonia, and ions diffuse under pressure into Bowman's capsule.
Below Bowman's capsule, tubules loop {proximal convoluted tubule}, and active transport returns glucose, amino acids, salts, and water by reabsorption to blood.
Proximal convoluted tubules dip down into kidney medulla and then back up to kidney cortex {Henle loop} {loop of Henle}.
In kidney cortex, looped regions {distal convoluted tubule} secrete selected substances back into urine from blood for augmentation.
Distal convoluted tubules go into kidney medulla {collecting tubule}, where countercurrent processes regulate water concentration, as low-concentration fluid passes by high-concentration fluid in opposite direction and diffusion balances water in blood and urine.
Collecting tubules can become funnel-shaped chambers {renal pelvis}.
Bone marrow, thymus, spleen, liver, and lymph nodes {immune system, organ}| protect body from invading organisms.
self
Immune system can recognize organism cells, because all body cell-membrane outsides have same cell-recognition glycoproteins.
antibodies
Immune-system cells can recognize antibodies, because antibodies complex with cell-recognition glycoproteins.
humoral immunity
Immune system can kill bacteria and viruses in cell fluids.
cellular immunity
Immune system can absorb body cells that have been damaged by viruses or bacteria and regulate immune system.
evolution
Humoral immunity and cellular immunity both come from same precursor cells during development.
acidity
Stomach acidity and urine acidity kill and suppress bacteria.
Several thousand different antigen-specific B cells are present {clonal-selection theory}, even in fetus.
Wax {ear wax} {wax, ear} can block ear bacteria.
Lymph, leukocytes, bacteria, and tissue leave residues {pus}|.
After healing, lymphocytes change to connective tissue {scar tissue}|.
Tears {tears} are antibacterial.
Organs from other organisms can replace same organs in individuals {transplantation}|. Immune system typically attacks foreign tissue.
Humoral immunity uses immune-system cells {macrophage}| that find antigens and process them.
Precursor cells {hemopoietic stem cell} (HSC), trapped inside bone-marrow special-cell {stromal cell} pockets, make all immune-system cells.
Hemopoietic stem cells divide to make cells {multipotent progenitor cell} (MPP) that move out of stroma and make hemopoietic stem cells that stay in stroma. Multipotent progenitor cells divide into myeloid progenitors and lymphoid progenitors. Myeloid progenitors divide into granulocytic/monocytic precursors and megakaryocytic/erythrocytic precursors. Lymphoid progenitors divide into B-cell precursors and T-cell precursors.
Mammalian immune-system bone-marrow cells {B cell}| synthesize and secrete antibodies and migrate to spleen, liver, and lymph nodes. If antigens meet B cells with correct antibodies, B cells transform into plasma cells.
antibodies
B cells differentiate from making IgM to making IgG to making IgA. B cells transpose variable region, located far from constant-region gene, to joining region, to make different antibodies. Enhancer activates only one variable-gene promoter. Vertebrate immune-system B cells use controlled transposition to make one antibody. Antibodies have constant regions. Various joining regions can attach to constant region. Various variable regions, located far from constant region in genome, can transpose to joining region.
Cells {memory cell} can take information back to lymph nodes or spleen, where memory cells change to plasma cells.
Cells {plasma cell}| can come from B cells. Plasma cells are lymphocytes that make antibodies and bind to foreign proteins. They make only one antibody type, which reacts with antigen to form precipitates for phagocytization. Humoral system makes 2000 antibodies per second for several days to prevent re-infection. Immature plasma cells in fetus that make antibodies against self normally die, leaving only antibodies against foreign molecules at birth.
IgD are on B-cell surfaces. IgE starts cells {mast cell}| that make histamine.
Immune-system cells {natural killer cell} can attach to B cells at temporary synapses to check if they are functioning.
In third and fourth pharyngeal pouch, thymus immune-system cells {T cell}| produce lymphokines from precursors. T cells can phagocytize foreign cells and viruses {cellular immunity, T cell}. Cytotoxic T cells absorb damaged cells.
cell surface
T cells have surface protein receptors. These glycoproteins can have alpha, beta, gamma, and delta subunits. Receptor genes for these proteins are similar to immunoglobulin genes. Immunoglobulin superfamily has similar constant, joining, diverse, and variable regions and similar promoters.
T cells {CD4+ T lymphocyte} {helper T cell} can have cell-surface CD4-protein receptors {co-receptor}, which assist T-cell receptors. Helper T cells have T-cell receptors.
process
Helper T cells start disease-organism killing. Helper T cells secrete lymphokines, such as interleukin, interferon, colony-stimulating factor, and tumor necrosis factor. Lymphokines activate cytotoxic T cells, signal B cells to make antibodies, attract macrophages and platelets with chemotactic factor, multiply helper T cells, and multiply immune precursor cells.
regulatory T cells
5% to 10% of helper T cells have CD25 surface protein and Foxp3 transcription factor and inhibit autoreactive CD4+ T lymphocytes.
problems
CD4+ T lymphocytes can alter to cause multiple sclerosis, insulin-dependent diabetes of youth, and rheumatoid arthritis.
Helper T cells {regulatory T cell} {CD4+CD25+ T cell} {T-reg cell} {T regulatory cell} can inhibit helper-T-cell immune responses, rather than secrete cytokines or engulf infected cells. 5% to 10% of CD4+ T lymphocytes are regulatory T cells.
receptors
Regulatory T cells have T-cell receptors, CD4-protein receptors, and CD25 surface proteins, which are in interleukin-2 receptors. Interleukin-2 excites regulatory T cells.
transcription
They have Foxp3 transcription-factor protein, which makes molecules that can disable autoreactive T cells.
Perhaps, antigen-specific receptors are stronger than the ones for autoreactive CD4+ T lymphocytes. Perhaps, regulatory T cells inhibit antigen-presenting cells from showing antigen. Perhaps, regulatory T cells cause antigen-presenting cells to release inhibitory cytokines. Perhaps, regulatory T cells inhibit autoreactive CD4+ T lymphocytes directly.
problems
Foxp3-gene mutation can cause immune dysregulation polyendocrinopathy enteropathy X-linked chromosome syndrome {IPEX syndrome} and autoreactive immune systems. Scurfy mice have autoreactive immune systems.
T cells {dendritic cell} can have surface molecules that bind to non-self proteins and attract T cells to breakdown protein. Then they usually die.
Cells {antigen-presenting cell} can contact T cells, to present protein fragments {supramolecular activation cluster, antigen} that they removed from viruses or bacteria, and so activate T cells. Supramolecular-activation clusters have outer rings for adhesion and central spots for recognition. Proteins move to form patterns, using cytoskeletons.
B cells and T cells make antibodies against antigens {adaptive immune system}.
T cells can phagocytize foreign cells and viruses {cell-mediated system} {cellular immunity}|. After contacting cells having different MHC surface proteins, lymphocytes change to macrophages, as antigen combines with special RNA, which engulf foreign cells. Memory cells take information back to lymph nodes and spleen, where memory cells change to plasma cells.
Immune system can kill bacteria and viruses in cell fluids {humoral immunity}| {humoral system}. Plasma cells make 2000 antibodies per second for several days to prevent reinfection.
The first time {primary immune response} bodies react to new antigens has greatest reaction {immune response}|. Later antigens cause reactions {secondary immune response}.
Natural killer cells can attach to B cells at temporary synapses {immune synapse}, to check if they are functioning. Natural-killer-cell receptor proteins check B-cell surface proteins. If no reception, acidic organelles move to synapse and inject chemicals to kill cells. Antigen-presenting cells contact T cells {supramolecular activation cluster, immunity} at immune synapses to present protein fragments that they removed from viruses or bacteria and activate T cells. Immune-synapse outer ring is for adhesion, and central spot is for recognition. Proteins move to form patterns, using cytoskeletons.
Body cells can react to pathogens {innate immune system}.
cells
Phagocytes include monocytes and dendritic cells. Monocytes become macrophages.
receptors
Pathogen molecules cause inflammation. Phagocyte Toll-like receptors recognize molecule types.
cytokines
Inside cells, TLRs make MyD88, Mal, Tram, and/or Trif. These make NF-kappaB, which enters cell nucleus to start cytokine production.
dendritic cells
After phage ingestion, dendritic cells carry phage fragments to lymph nodes to inform T cells.
Spleen, lymph nodes, liver, and bone marrow blood-vessel sinusoid cells phagocytize foreign cells {reticuloendothelial system}.
Immune system has rapid generalized responses {sickness response}| {acute phase response}.
purpose
Sickness response creates or saves energy.
process
Stress causes hypothalamus, pituitary, adrenal gland, and sympathetic nervous system to release hormones and transmitters, which bind to immune-cell receptors and regulate immunity. Activated immune cells release pro-inflammatory cytokines that affect neurons and glia, which coordinate hormone, behavior, and physiological changes related to fever. Physiological changes are fever, blood-ion-concentration reduction, increased white-blood-cell replication, and increased sleep. Blood-ion-concentration reduction denies minerals required by replicating bacteria and viruses. Behavior changes decrease social interaction, exploration, sexual activity, and food and water intake. Hormone changes increase hypothalamus, pituitary, adrenal, and sympathetic-nervous-system hormone release.
fever
Fever raises body temperature, so bacteria and viruses do not replicate rapidly, bacteria do not form protective outer coats, white blood cells replicate rapidly, and destructive enzymes function efficiently.
slow response
Immune system has slow selective response, which makes antibodies [Maier et al., 1994] [Maier and Watkins, 1998] [Maier and Watkins, 2000].
glia
Glia can act like immune cells.
Peptides {hexapeptide} can have shapes similar to 20 others, so they all bind same antibody.
Muropeptides {lectin} bind to NOD, such as NOD2, and NALP intracellular receptors and trigger cytokines and/or transcription factors. Lectins include mannose-binding lectin.
Helper T cells make molecules {cytokine}| that attract neutrophils and monocytes, which become macrophages: {colony-stimulating factor} {granulocyte-macrophage colony-stimulating factor} (GMCSF) {interleukin}. Tumor necrosis factor alpha {tumor necrosis factor} increases inflammation. Inside cells, Toll-like receptors make MyD88, Mal, Tram, and/or Trif. These make NF-kappaB, which enters cell nucleus to start cytokine production. Cytokines include interleukin-1, interleukin-6, interleukin-8, interleukin-12, and tumor necrosis factor-alpha. Interleukin-1 increases inflammation. Interleukin-6 activates B cells. Interleukin-8 is signal to neutrophils. Interleukin-12 activates T cells. Cytokines attract monocytes and neutrophils. Monocytes become macrophages.
Cells inflamed by injury, allergens, antigens, or invading microorganisms release 8-kDa to 16-kDa soluble proteins {chemokine}, to attract monocytes and granulocytes. Humans have 50 chemokines.
types
Alpha chemokines have amino acids between first two cysteines and have two other cysteines. Beta chemokines have no separation between first two cysteines and have two other cysteines. Gamma chemokines have two cross-linked cysteines. Lymph nodes, lungs, liver, and bone marrow express factors {stromal-cell-derived factor 1} from genes {SDF-1 gene} {CXCL12 gene}.
receptors
Chemokines bind to chemokine receptors {G protein-linked receptor}. Chemokine receptors (CXCR2) (CXCR4) (CCR7) include chemokine receptor 5 (CCR5), used by HIV-1.
receptors: effects
Binding to receptors causes adhesion-protein {B integrin} rearrangement, to increase adhesion to blood-vessel endothelial cells. Later, leukocytes pass between endothelial cells into tissue. Leukocytes use pseudopods and actin movement to migrate along chemokine concentration gradient. High chemokine concentration makes leukocytes produce cytokines, release granule contents, induce intracellular F-actin polymerization, form pseudopods, increase endothelial and other cells, promote vascularization, remodel tissue, heal wounds, and lyse lymphocytes.
Macrophages and endothelial cells make proteins {S100 protein}, such as S100A8 and S100A9, that signal for more macrophages to come.
Tumor necrosis factor, interleukin-l, and interleukin-6 cytokines {pro-inflammatory cytokine} cause sickness responses [Maier and Watkins, 1998] [Watkins and Maier, 1999] [Watkins and Maier, 2002].
In third and fourth pharyngeal pouch, thymus helper T cells secrete peptides {lymphokine}, such as interleukin, interferon, colony-stimulating factor, and tumor necrosis factor. Lymphokines activate cytotoxic T cells, signal B cells to make antibodies, attract macrophages and platelets with chemotactic factors, multiply helper T cells, and multiply immune precursor cells.
Helper T cells secrete lymphokine peptides, such as interleukin, interferon, colony-stimulating factor, and tumor necrosis factor. Lymphokines activate cytotoxic T cells, signal B cells to make antibodies, attract macrophages and platelets {chemotactic factor}, multiply helper T cells, and multiply immune precursor cells.
T cells have cell-surface protein receptors {immunoglobulin superfamily, antibody}. These glycoproteins can have alpha, beta, gamma, and delta subunits. Receptor genes for these proteins are similar to immunoglobulin genes. They have similar constant, joining, diverse, and variable regions and similar promoters. Immunoglobulin superfamily includes cell-adhesion proteins {neural-cell adhesion molecule}, growth-factor receptors, and lymphokine receptors. MHC genes are similar to genes for antibodies and T-cell receptors.
Antibodies {abzyme} can act like enzymes and bind to reaction transition states. 10% of such binding affects reaction rates.
Immune-system B cells make one antibody type {allelic exclusion} and secrete it into blood.
One antibody arm can bind to one molecule, and other arm to another molecule {bispecific antibody}.
Variable antibody regions have only three parts that actually bind to antigen {complementarity determining region} (CDR). Variable regions otherwise just align CDRs. Humanized antibodies use human antibodies with CDRs from monoclonal mice.
Toxins can replace antibody regions {effector region} used to determine immunoglobulin type, to deliver agents only to correct sites.
Antibody variable regions can attach to different constant regions for different immunoglobulin types {class switching}, so all immunoglobulin types use same antibody.
Antibodies have two longer proteins {heavy chain}. Heavy chains have variable regions at arm ends, diverse region, joining region, and three constant regions. Single genes are for constant regions. Heavy chains can come from 20 diverse-region genes. Heavy chains can come from four joining-region genes. Thousands of genes code for variable regions. How regions bind together also varies.
Y
Two heavy chains join in middle to make Y shapes.
types
Heavy chains have five types: alpha, gamma, delta, epsilon, or mu.
antibody types
Heavy-chain type determines antibody type: immunoglobulinA or IgA, immunoglobulinG or IgG, immunoglobulinD or IgD, immunoglobulinE or IgE, or immunoglobulinM or IgM. IgA binds to antigens in saliva, tears, and intestines. IgG and IgM go into blood and bind to antigens, bound antigen binds to cells, and IgG and IgM activate immune-system macrophages, which eat cells with bound antigen. IgD are on B-cell surfaces. IgE starts mast cells that make histamine. Perhaps, histamine defends against parasites. Immunoglobulin-E can attack worms.
Antibodies have two shorter proteins {light chain}. Light chains have variable regions at arm ends, joining region, and constant region. Single genes are for constant regions. Light chains can come from five joining-region genes. Thousands of genes code for variable regions. How regions bind together also varies. Light chains parallel Y arms on outsides. Light chains have two types: kappa or lambda.
Immune-system genes rearrange in early infancy. Antibody gene can join second gene {joining gene} by deleting DNA between them. Joining genes join trunk gene, which determine mobility level. Joined genes determine antigen.
Immune-system genes rearrange in early infancy. Antibody gene can join joining gene by deleting DNA between them. Joining genes join gene series {trunk gene}, which determine mobility level. Joined genes determine antigen.
Beta2-microglobulin and other cell-surface glycoproteins {major histocompatibility protein}| (MHC) can be for cell recognition.
number
Humans can have 100,000 different surface-protein sets.
polymorphism
Cell-surface glycoproteins can be highly polymorphic.
genes
MHC genes are similar to genes for antibodies and T-cell receptors {immunoglobulin superfamily, MHC}. MHC genes do not vary through rearrangement. MHC Class I genes are expressed in all cells. MHC Class II genes make glycoproteins for B cells and macrophages. Other MHC genes make blood-complement proteins and other cell-surface proteins.
receptors
Cytotoxic T cells recognize glycoproteins.
metabolism
MHC Class I glycoproteins cut bacterial and viral antigens into peptides, which then bind to cleft in MHC Class II glycoproteins. Helper T cells recognize antigen/MHC Class II complexes. Complement proteins CD4 and CD8 bind MHC to receptors at constant antibody regions and signal T cells to activate.
T cells can have antigen receptors {T cell receptor} (TCR).
Cell-surface proteins can have classes {tissue typing}|.
Phagocyte-cell receptors {Toll-like receptor} (TLR) can recognize lipopeptides. TLR1 detects bacterial lipopeptides and parasite GPI-anchored proteins. TLR2 detects Gram-positive-bacteria cell-wall lipoteichoic acids. TLR3 detects virus double-stranded RNA. TLR4 detects Gram-negative bacteria by binding to lipopolysaccharide. TLR5 detects bacteria-flagella flagellin. TLR6 detects fungi zymosan. TLR7 detects virus single-stranded RNA. TLR8 detects virus single-stranded RNA. TLR9 detects bacterial and virus CpG sequences.
metabolism
Inside cells, TLRs make MyD88, Mal, Tram, and/or Trif. These make NF-kappaB, which enters cell nuclei to start cytokine production.
evolution
TLR are in plants and animals. Tobacco has N protein that detects tobacco mosaic virus. TLR probably started in one-celled organisms.
A body-tube network {lymphatic system}| leads to left shoulder vein.
By diffusion, lymphatic system collects fluid left over from blood {lymph}|. Lymph is clear and colorless, has white blood cells, has no red blood cells, and has low protein concentration. At intestine, lymph absorbs most fats. Lymph moves by skeletal muscle movements and by breathing. Cancer can metastasize through lymph.
Lymph vessels join at nodes {lymph node}| that make lymphocytes and remove dust and bacteria.
Lymph tissues {adenoid}| can be high in throat, behind nose. Adenoids grow until age 5 to 7.
Body systems {muscle}| can have 600 muscles and be 40% of human body weight.
types
Muscles are skeletal, cardiac, or smooth muscles.
types: opposites
Muscles have opposing muscles: flexor-extensor, abductor-adductor, elevator-depressor, pronator-supinator, and sphincter-dilator.
parts
Muscles have a fixed end {origin, muscle}, middle {belly, muscle}, and moving end {insertion, muscle end}.
parts: fiber types
Skeletal muscles have two fiber types. Slow fibers do not fatigue, are slower and weaker, have calcineurin, and use fat for periodic or sustained movements. Fast fibers fatigue, are stronger and faster, have 2B myosin and/or ACTN3 protein, and use sugar for rapid movements.
contraction
Muscles can shorten by up to one-third. Nerve stimuli activate muscles.
metabolism: PPAR-delta protein
PPAR-delta proteins regulate fat-catabolism genes and increase metabolism. PPAR-delta proteins make muscles with more slow-twitch fibers.
metabolism: lactic acid
Muscles make lactic acid from glucose or glycogen. Uptake transporter molecules carry lactate into mitochondria. This mechanism becomes more efficient with more endurance exercise.
metabolism: dystrophion
Dystrophin protein transfers energy to prevent muscle-fiber damage. Duchenne muscular dystrophy has no dystrophin.
metabolism: satellite cells
In response to insulin-like growth factor I, satellite cells divide and provide new nuclei to muscle cells. Myostatin decreases satellite-cell division.
Disuse can cause muscle wasting {atrophy}|.
Belgian Blue and Piedmontese cattle {double-muscled} have myostatin that binds but does not signal.
Low ATP and glycogen can cause inability to contract {muscle fatigue}| {fatigue, muscle}.
Perhaps, lactic acid accumulates while using muscles {oxygen debt}|. However, this idea is not correct.
Muscles have moving ends {insertion, muscle}.
Muscles can have sustained muscle contraction {tetanus, muscle}|.
Muscles always have slight contraction {tonus}|.
Nerve signals travel through muscles {latent period}, followed by contraction and then relaxation.
Muscle cells uptake glycogen and oxygen to recover from contraction {recovery time}.
After contraction, muscles are not responsive {refractory period, muscle}.
Body has muscles {musculature}|.
Muscles are across abdomen {midriff}|.
Muscles across abdomen can become weak and sag {paunch}.
muscles or tendons {sinew}|.
down abdomen middle {abdominal muscle}.
back {back muscle}.
upper-arm front {bicep}|.
seat {buttock}|.
lower-leg back {calf muscle}|.
over shoulder {deltoid}|.
seat {duff, muscle}.
face {facial muscle}.
lower arm {forearm muscle}.
lower-leg back {gastrocnemius}|.
over rear end {gluteus maximus}|.
upper-leg back {hamstring}|.
neck {neck muscle}.
over breast {pectoral}|.
tail muscle {prehensile}|.
between ribs {rib muscle}.
upper-leg front {thigh}|.
neck back {trapezius}|.
upper-arm back {tricep}|.
twist appendage {rotator}.
pull away from spine {abductor}.
pull toward spine {adductor}.
raise {elevator muscle}.
lower {depressor muscle}.
close {sphincter}|.
open {dilator}.
bend {flexor muscle}.
extend {extensor muscle}.
pull up and forward {pronator}.
pull down and backward {supinator}.
Brain, spinal cord, and peripheral nerves {nerve} have pathways.
Brain and spinal cord float in fluid {cerebrospinal fluid}|. Cerebrospinal fluid is in central canal and between neuron layers. Brain cells in central-canal enlargements make cerebrospinal fluid.
Neuron clusters {ganglia}| {ganglion} coordinate reflex arcs over body region to perform function. Ganglia have cell bodies in center and axons on outside. Ganglia perform orienting responses, focus attention, detect features, select behavior patterns, and initiate behavior sequences.
Nerves can have nerve-process outgrowths {neurite}.
Axons can contact both neuron and interneuron {synaptic triad}. Synaptic-triad processing can turn tonic signal into phasic signal.
Nerve ganglia can group {plexus}|.
Plexus {solar plexus}| {celiac plexus} behind stomach near celiac artery is largest autonomic center and controls adrenal gland secretion and intestine contraction.
Motor nerves {autonomic nervous system}| (ANS) connect to glands and non-striated smooth muscles and are always active. ANS controls heart, lungs, digestive tract, bladder, sweat glands, hair muscles, iris muscles, and arterioles. Such control relates ANS to emotion. Autonomic nervous system has sympathetic autonomic system and parasympathetic autonomic system.
Intestinal sensory nerves {enteric nervous system} measure distension and toxicity, making people feel full or nauseous [Gershon, 1998].
Brain and spinal cord nerves {central nervous system}| (CNS) connect to peripheral nerves in spine and body. Most CNS motor nerves go to voluntary muscles. Some CNS motor nerves go to glands and smooth muscles and are in autonomic nervous system.
Body nerves {somatic nervous system} {peripheral nervous system}| (PNS) can go to muscles, skin, and mucous membranes, or go to smooth muscles and glands, and are in autonomic nervous system. PNS includes 12 cranial-nerve pairs and 31 spinal-nerve pairs.
Central and peripheral nerves {parasympathetic autonomic system}| {parasympathetic nervous system} can stimulate micturition, defecation, alimentation, and sexual function.
Central and peripheral nerves {sympathetic autonomic system}| {sympathetic nervous system, function} can inhibit smooth-muscle cells.
functions
They regulate temperature by secreting sweat. They contribute to threat and aggression behaviors. They dilate pupils. They make hair stand on end. They control blood distribution throughout body by dilating or constricting blood vessels. They contribute to male sexual activities.
chemicals
Sympathetic-nervous-system postganglionic aminergic neurons synthesize and release noradrenaline. In sympathetic autonomic ganglia, presynaptic cholinergic fibers excite acetylcholine neurons and LHRH-like-peptide neurons. LHRH-like-peptide diffuses several micrometers to make slow excitatory postsynaptic potential (EPSP).
Human brains {brain} have divisions and cephali [Braak, 1976] [Braak, 1980] [Brodmann, 1914] [Bullock et al., 1977] [Caplan, 1980] [Carter, 1999] [Carter, 2003] [Crick and Jones, 1993] [Crick and Koch, 1998] [Ewert, 1980] [Glynn, 1999] [Harrison et al., 2002] [Heeger et al., 2000] [Hilgetag et al., 1996] [Jastrow, 1981] [Johnson, 1986] [Kessel and Kardon, 1979] [Kimura, 1992] [Le Bihan et al., 2001] [La Cerra and Bingham, 2002] [Logothetis, 2002] [Logothetis et al., 1999] [Logothetis et al., 2001] [Mathiesen et al., 1998] [Rees et al., 2000] [Rempel-Clower and Barbas, 2000] [Schüz and Miller, 2002] [Shepherd, 1991] [Waxman, 2000] [Webster et al., 1994] [Young, 2002] [Zeki, 1993].
neuron number
Human brains have 10 billion neurons.
weight
Human brain is 2% of body weight. Larger brains can dissipate heat better.
Two genes control brain size.
size compared to body size
Brain size, energy, and metabolism vary with body size to the 3/4 power, as determined by blood-vessel or neuron-axon branching patterns.
species
Elephant-nosed fish {mormyrid} live in muddy water. Mormyrids have relatively large brains, because they have electric organs and electroreceptors.
Rays and sharks are predators and have relatively large brains.
Warm-blooded animals have relatively large brains, to improve predation.
Fruit eaters and carnivores have relatively large brains compared to insect and leaf eaters. Fruit eating and meat eating require smaller digestive systems.
Primates have big brains. Bigger brains require more time to mature, fewer babies, and longer time between babies, so primates live longer than most species. Larger relative neocortex size associates with bigger social groups in primates.
individuality
Brains differ greatly in structure and connectivity.
Most animals have similar brain-volume to body-volume ratios {encephalization quotient} (EQ). Mammals have ratio seven times more than average. Chimpanzees have ratio three times more than average. Dolphins have higher EQ than great apes.
Brain has axon tracts {peduncle}.
Cell bodies and unmyelinated axons {gray matter}| are 60% of brain volume. Unmyelinated axons are 55%. Cell bodies are 5%.
Myelinated axons {white matter}| are 40% of brain volume.
Anterior cingulate gyrus, cortex, and basal ganglia make circuit {anterior attention network} that detects expected location. Cortex notes matches, and basal ganglia note mismatches.
Dorsolateral prefrontal cortex, cingulate nucleus, frontal eye fields in area 8, posterior parietal lobe in area 7a, pulvinar nucleus, and superior colliculus change object attention {attention shift} [Astafiev et al., 2003] [Corbetta, 1998] [Kustov and Robinson, 1996] [Mountcastle et al., 1981] [Sheliga et al., 1994] [Shepherd et al., 1986] [Wurtz et al., 1982].
The largest descending fiber tract {corticospinal motor tract} has one million axons from primary motor, supplementary motor, and premotor cerebral cortex layer-5 pyramidal neurons to spinal cord segment neurons to control precise finger and toe movements. Spinal-cord axons initiate skilled muscle movements at alpha motor neurons. Pre-central gyrus has the most corticospinal motor-tract neurons.
Lateral corticospinal tract, only in mammals, controls voluntary muscles. Anterior corticospinal tract does not cross over and is for posture and trunk position.
Signals from skin, muscles, tendons, and joints travel in spinal-cord dorsal column large and fast fibers to gracile nucleus and cuneate nucleus, then to thalamus medial lemniscus, then to post-central gyrus {dorsal-column-medial-lemniscal pathway} {DCML pathway}, which is for reflexes and rapid movement.
Axons from retina nasal halves, after traveling in optic nerve, cross over {decussation, axon} to other side in brain front middle optic chiasma.
Tracts {extrapyramidal tract} can include caudate nucleus, globus pallidus, putamen, red nucleus, reticular formation, and substantia nigra unmyelinated axons.
Between thalamic and cortical regions, one connection is feedforward {feedforward circuit}, and the other is feedback {feedback circuit}. Connections never combine both.
feedforward
Feedforward axons begin in layers 2 and 3 and end in layer 4.
feedback
Feedback axons begin in layers 5 and 6 and end in layers 1, 2, 3, and 6. Feedback goes to larger regions than feedforward [Barone et al., 2000] [Bullier, 2001] [Bourassa and Deschenes, 1995] [Cauller and Kulics, 1991] [DiLollo et al., 2000] [Grossberg, 1999] [Grossenbacher, 2001] [Heimer, 1971] [Hupe et al., 1998] [Johnson and Burkhalter, 1997] [Lamme and Roelfsema, 2000] [Lamme and Spekreijse, 2000] [Kosslyn, 1980] [Kosslyn, 1994] [Kosslyn, 2001] [Ojima, 1994] [Pollen, 1995] [Pollen, 1999] [Pollen, 2003] [Rhodes and Llinás, 2001] [Rockland et al., 1997] [Rockland, 1994] [Rockland, 1996] [Rockland, 1997] [Rockland and Van Hoesen, 1994] [Salin and Bullier, 1995] [Supèr et al., 2001] [Wiener, 1947] [Williams and Stuart, 2002] [Williams and Stuart, 2003].
Networks {frontal lobe attentional network} can be for attention, executive functions, decision making, voluntary movements, and stimulus conflict resolution [Mountcastle et al., 1981] [Wurtz et al., 1982].
Cerebrum, basal ganglia, brainstem, and cerebellum send to motor-neuron reciprocal-inhibition neurons {internuncial neuron}.
Systems {interoceptive system} can control homeostasis and chemical changes. Hypothalamus can sense molecules that can cross blood-brain barrier. Circumventricular organs, brainstem area postrema, and cerebrum subfornical organs lack blood-brain barrier and can sense large molecules.
Networks {limb premotor recurrent network} can spread positive feedback for limb command generation. Purkinje-cell bands converge on small nuclear-cell clusters in topographically organized recurrent circuits, with thalamic, motor cortical, rubral, pontine, and lateral-reticular neurons, which send commands to spinal cord along corticospinal and rubrospinal fibers.
A pain-sensing system {nociceptive system} {nociceptive pain response} can use superior colliculus, spinal cord, and thalamus neurons. It has opiate receptors, so opiates can inhibit it. Tactile, nociceptive, and thermal receptor systems interact.
Axons from each-retina nasal half, after traveling in optic nerve, cross over {decussation, optic nerve} to other side in brain front middle {optic chiasma}. Temporal-lobe half-retina axons, after traveling in optic nerve, remain on same side at optic chiasma, so visual-field right half goes to right lateral geniculate body and cerebrum, and left half goes to left.
Brain networks {premotor network} can control eye movements using recurrent pathways.
functions Separate premotor networks control smooth and saccadic eye movements. Separate premotor networks control horizontal and vertical movements.
input
Premotor network receives vestibular-sense input from semicircular canals. Vestibular nucleus signals use velocity coding. On brainstem sides, medial-vestibular-nucleus neurons interconnect with prepositus-hypoglossius neurons and with intermediate types. Prepositus hypoglossius neuron signals use position coding. Brainstem sides interconnect through recurrent inhibitory pathway.
Mammalian tracts {pyramidal tract} can excite motor neurons and enhance reflexes. Muscle actions, but not skilled-movement learning or memory, require pyramidal tract, which is bigger if cortex is bigger.
Septum and hippocampus circuit {septo-hippocampal system} affects contextual and spatial memory.
Perirhinal cortex receives multisensory input and sends to hippocampus, which sends to diencephalon {short-term memory circuit} to make short-term memory [Aksay et al., 2001] [Compte et al., 2000] [Courtney et al., 1998] [de Fockert et al., 2001] [Eichenbaum, 2002] [Fuster, 1973] [Fuster, 1995] [Fuster, 1997] [Gazzaniga, 2000] [Goldman-Rakic, 1992] [Goldman-Rakic, 1995] [Goldman-Rakic et al., 2000] [Miller, 1999] [Miller et al., 1996] [Pochon et al., 2001] [Rao et al., 1997] [Romo et al., 1999] [Squire and Kandel, 1999] [Squire, 1992].
Vibration, steady pressure, and light touch information goes from skin, to spinal-cord dorsal root, to brainstem lower end, to thalamus ventro-basal complex, and to primary somatosensory cerebral cortex {skin sensory circuit}. All senses have similar circuits.
Body systems {somatosensory system} can have viscera, vestibular, proprioception, and kinesthesia systems and autonomic, homeostasis, and fine touch functions. Somatosensory system uses reticulum, monoamine nuclei, acetylcholine nuclei, hypothalamus, basal forebrain, insular cortex, S2 cortex, and medial parietal cortex.
Body systems {spatial attention system} can regulate inferotemporal neurons and filter inferotemporal-area input from selected stimulus and memory, for pattern recognition.
Proprioception input goes to nucleus dorsalis, then to ipsilateral dorsal spinocerebellar tract or to contralateral ventral spinocerebellar tract, then to cerebellum, and then to cerebral cortex {spinocerebellar tract}. Dorsal and ventral spinocerebellar tracts are for movement initiation or for position information from muscle spindles, Golgi tendon organs, and touch receptors.
Tracts {spinoreticular tract} can be for dull and chronic pain from soma.
Diffuse touch, pressure, acute pain, and thermal fibers {spinothalamic pathway} {spinothalamic tract} {protopathic pathway} {spinothalamic system} go to substantia gelatinosa as unmyelinated fibers, cross to contralateral spinothalamic tracts, go through reticular system, go to thalamus ventral posterior nucleus, and end at cerebrum. Spinothalamic tract has small and slow feedback nerves for pain inhibition.
Older unconscious visual pathway {tectopulvinar pathway} {tectofugal pathway} goes from tectum to superior colliculus, thalamus pulvinar nucleus, and parietal lobe and is for visual spatial orientation, orienting responses, and movement to focus attention. Geniculostriate and tectopulvinar pathways interact [Ramachandran, 2004].
Spinal-cord tracts {tectospinal tract} can be for reflex head turns.
Pathways {vestibulo-ocular pathway} from retina to vestibular system to cerebellum can allow eye to track moving objects smoothly while head turns.
Spinal-cord tracts {vestibulospinal tract} can be for posture reflexes.
Circuits {dorsal system} {dorsal pathway} {vision-for-action} {where pathway} {how pathway} {high path for vision} {ambient system} can go from occipital lobe area V1 to mediotemporal (MT) area, parietal area PG, posterior parietal area (PPC), and dorsolateral prefrontal cortex [Bridgeman et al., 1979] [Rossetti, 1998] [Ungerleider and Mishkin, 1982] [Yabuta et al., 2001] [Yamagishi et al., 2001].
functions
Dorsal pathway processes object location, size, parts, and characteristics. It converts spatial properties from retinotopic coordinates to spatiotopic coordinates. It tracks unconscious motor activity and guides conscious actions, such as reaching and moving eyes.
output
Dorsal system sends to amygdala and hippocampus to form visual memories [Heimer, 1971].
Circuits {ventral system} {vision-for-perception} {what pathway} {low path for vision} {focal system} can go from occipital-lobe area V1, through areas V2 and V3 and V4, to inferior temporal lobe area TE, limbic system, and ventrolateral prefrontal lobe [Bridgeman et al., 1979] [Epstein and Kanwisher, 1998] [Haxby et al., 2001] [Heimer, 1971] [Ishai et al., 2000] [Milner and Goodale, 1995] [Ungerleider and Mishkin, 1982].
functions
Ventral system is for recognition. It classifies stimuli shapes and qualities. It registers new category instances. It responds to patterns, shapes, colors, and textures, with earlier neurons for smaller and later neurons for bigger. It does not contain representations but organizes input into familiar packets.
output
Ventral system sends to amygdala and hippocampus to form visual memories.
Cerebrum spatiotemporal firing patterns {brain code} {cerebral code} can represent actions or perceptions.
switches
Neurons are switches. They contrast below-threshold with above-threshold.
coding
Contrast or mark sequences can be codes and carry messages. Each millisecond, axon locations either have or do not have spikes.
Times between spikes can code for timing intervals.
Number of spikes per second reflects average voltage difference at axon hillock.
coding: types
Perhaps, neuron code uses average number of spikes per 100 millisecond {firing rate code}. Perhaps, neuron code uses spike timing {temporal coding}, for synchronization and oscillation.
Perhaps, neuron code is probabilistic [Rao et al., 2002].
Perhaps, neuron code uses synchronous firings {synfire chain model} [Abeles, 1991] [Abeles et al., 1993].
Perhaps, neuron code uses precisely timed spike or burst {first-time-to-spike model} [VanRullen and Thorpe, 2001].
Perhaps, brain uses standing, traveling, rotating, or compression waves [Ermentrout and Kleinfeld, 2001].
contrast
Contrast is relative intensity, intensity difference or ratio.
contrast: space
ON-center neurons have excitation when input is on their receptive-field center and inhibition when input is on annular region, so they detect contrast between central and annular regions. OFF-center neurons have excitation when input is on annular region and inhibition when input is on center.
ON-center neurons pair with OFF-center neurons and work together to enhance contrast.
contrast: opposites
Opponent-process neurons detect receptor-input ratio and so contrast extremes.
contrast: categories
Categorization neurons use thresholds to establish and contrast categories.
contrast: orientation
Cortical neurons in orientation column pair with neurons in orientation column for perpendicular or other orientation. They also pair with neurons for no orientation. The pairs enhance contrast.
contrast: process
Neurons and neuron pairs find relative values and so contrast by lateral inhibition, spreading activation, and comparing opposite receptors.
contrast: boundaries
Contrast between two things marks a boundary or threshold. No value difference means both are the same, with no boundary, mark, point, or information. Markers/boundaries are information bits. Contrasts, markers, or boundaries are like ON or OFF, 0 or 1, YES or NO. Markers provide signs or landmarks, such as indexes, for references, to which other signs can relate.
contrast: boundaries and space
Boundaries are markers in space. The idea of space depends on the idea of boundary. Boundaries separate two regions, such as self and not-self or inside and outside.
Codes {bursting} can use spike bursts followed by quiet periods [Crick, 1984] [Koch, 1999] [Koch and Crick, 1994] [Lisman, 1997].
Perhaps, neuron code uses neurons with precise ranges {population coding} {pattern coding} {Across-Fiber Pattern theory}. For example, movement trajectories can be sums of many neuron outputs. Brains can store representations as values in neuron sets. Repeated input activates same neuron population. Similar input activates similar neuron population. Difference between two patterns is quantitative difference between populations. With population coding, patterns and concepts have geometry [Hahnloser et al., 2002] [Perez-Orive et al., 2002].
Perhaps, for each stimulus, brain has one receptor and one neural path {labeled line}.
Perhaps, neuron code uses few neurons with precise location or distance {sparse coding} [Hahnloser et al., 2002] [Perez-Orive et al., 2002].
Perhaps, neuron code uses few spikes with precise timing {sparse temporal coding} [Hahnloser et al., 2002] [Perez-Orive et al., 2002].
Brain performs computations {brain computation}. Brain scanning and brain lesion analysis shows that brain regions mediate brain functions {localism}. Brain regions have functions, and brain functions involve several brain regions coordinating sequentially and simultaneously [Carter, 1999].
input and output
Neuron populations receive input-signal sets and calculate output-signal sets. For functions, brain has several paths that make same output from same input.
All central-nervous-system input goes to cerebellum, reticular formation, and thalamus. Input that can eventually cause sense qualities goes to sense neurons in thalamus and then cerebrum. Brain inputs and outputs coordinate. For example, motor neurons and muscle receptors link.
input and output: global information
All brain information uses many neurons, which process only local information, but result is global [Black, 1991].
input and output: convergence
Inputs from different cortical regions {convergence region, vision} converge on cortical regions {convergence zone}. Convergence-zone output includes feedback to input cortical regions. Brain has more than 1000 convergence regions and more than 100 convergence zones.
input and output: distributed processing
Brain has many recurrent, lateral intracortical connections, and neurons receive from large spatial area. No neuron has simple direct circuit [Abbott et al., 1996] [Dayan and Abbott, 2001] [Rao et al., 2002] [Rolls and Deco, 2002] [Shadlen et al., 1996] [Zhang et al., 1998].
More than 50% of cortical neurons send output to distant cortical areas.
input and output: important information
Brain gives command to region with the most-important information.
coding
Information theory applies to neural coding, and one impulse can carry more than one information bit [Rieke et al., 1996] [Shannon and Weaver, 1949].
coding: repetition
Brain cells typically experience same correlations, associations, and comparisons many times. Processing in small brain region repeats often. Repetition improves efficiency as cells modify.
coding: electrochemical coding
Axon ion flows change voltage, and receptor-membrane neurotransmitters change voltage, so neuron coding is electrochemical.
coding: discrete coding
Neurons generate neurotransmitter packets and action potentials, rather than graded potentials, so information flows are discrete on-or-off sequences rather than continuously-varying voltages or currents.
coding: frequency code
Neuron impulse frequency indicates both time interval and intensity. Spike frequency F above normal frequency NF is constant C times power p of receptor displacement X from normal N: (F - NF) = C * (X - N)^p.
Neuron spike frequency never exceeds 800 spikes per second and never becomes 0. At rest, frequencies can be few per second or hundreds per second.
coding: information amount
If axon-hillock depolarization or no depolarization can happen every millisecond, millisecond intervals are either on or off. In 100 milliseconds, 2^100 bits can travel down axon. 2^100 bits is approximately 10^30 bits, which is approximately 1000^10 bits.
If number of possible letters, digits, and punctuation marks is 1000, 1000^10 bits can represent ten-letter words, labels, indexes, or pointers, so one neuron acting for 100 milliseconds can code for any ten-letter word. One hundred thousand neurons acting for 100 milliseconds can code for any million-letter string. One hundred thousand neurons acting for 100 milliseconds can code for any million-dot image, if dots can have 1000 levels of gray and color.
One hundred neurons acting for one millisecond can code for any ten-letter word. One neuron acting for 10^7 milliseconds, approximately 3 hours, can code for any million-letter string or million-dot image.
coding: summation
Axons depolarize for percentage of time. In time intervals, such as ten milliseconds, so short that receptors do not have time to change, depolarization sequences with same total number of depolarizations have equivalent physiological effects, no matter in what order signals arrived. In these cases, axon coding is not a significant factor, and irregular conduction rates do not matter. Ten-millisecond intervals have 10 instants that can be ON or OFF, and so intervals have 2^10 different possible sequences. However, such short time intervals have only 11 physiological possibilities: 0 to 10 total depolarizations.
computations
Neurons promote, amplify, block, inhibit, or attenuate signals. Neuron circuits can lower thresholds, switch signals, amplify signals, filter frequencies, set thresholds, control currents, direct flows, induce currents, control voltages, compare signals in time and space, add quantities, multiply quantities, and perform logical operations.
Most visual cortical neurons respond to line contrasting with background. Output maximizes if contrast is in receptive-field middle. Response falls off rapidly as contrast line moves to either side. Function looks like Gaussian distribution with large variance or looks like two sigmoidal functions joined at maximum. Most neurons behave like Gaussian HBF units, rather than multilayer-perceptron (MLP) sigmoidal units.
computations: potentiation
Nitric oxide from receptor neuron maintains sending-neuron long-term potentiation (LTP). Cyclic AMP second messenger sensitizes receptor neuron. NMDA glutamate receptors sensitize receptor neuron. Potentiation makes neuron reach threshold with lower input than normal excitation level.
computations: association by neurons
Interneuron can detect stimulus timing and amplitude between two pathways. Two pathways can both contact an interneuron that controls secondary circuit. If both pathways carry current simultaneously, secondary circuit maintains current. If both pathways carry no current or only one has current, secondary circuit has no current. Interneuron detects simultaneous pathway activation.
computations: conditional statement
Depolarization can happen only if all inputs to neuron are active. Depolarization can happen if one input to neuron is active. Depolarization can happen only if some inputs are active and some inactive.
computations: difference
Neurons compare signals to detect change or difference, rather than absolute values.
computations: feedback
Neuron circuits with excitatory and inhibitory feedback have short, synchronous discharges in local clusters.
computations: indexing system
Brains have index list to rapidly locate information.
computations: inhibition
Inhibition dampens neuron signals and more quickly returns neurons to resting states, allowing shorter time intervals and quicker responses. Between two stimuli, inhibition increases stronger signal and decreases competing weaker stimulus. Thus, inhibition can enhance weak stimulus that has only weaker stimuli nearby in space or time.
computations: inverse model
If supplied with sample responses, inverse model can predict input commands.
computations: movement initiation
Movement initiation and programming are separate asynchronous processes. Deciding to perform action corresponds to building positive feedback in limb premotor network.
computations: movement programming
Movement initiation and programming are separate asynchronous processes. Cerebellar cortex programs which movement to perform. Programming can happen while preparing movement or moving.
computations: positive whole numbers
Synaptic transmission uses neurotransmitter-molecule packets. Axon depolarizations are independent and countable. Therefore, neurons use whole number calculations and whole number ratios, with no fractions or real numbers. Because neurotransmitter molecules and axon depolarizations have no opposite, neurons use only positive numbers, never negative numbers.
computations: synchronizing
Neuron reciprocal interactions can synchronize signal phase, if reciprocal signal delay is less than one-quarter oscillation. Neuron excitatory reciprocal connections can find feature relations by enhancing, prolonging, and synchronizing neuron responses.
computations: timing
Brain uses time-delay circuits, inhibitory signals, and circuit-path rearrangements to time neuron events.
computations: transformations
Brain can use geometric ratios, translations, rotations, and orientations to represent distances and manipulate lines and shapes.
validation
Brain sends inputs along several paths to cross-validate processing and representations by comparing redundant process outputs.
Interneurons can associate reflex-pathway nerve-cell states with other reflex-pathway nerve cell states {association triad neuron mechanism}.
interneurons
Nerve cells in pathways from sensation to action connect using interneurons for cellular associative learning. Interneurons laterally excite or inhibit main neurons.
process
Cell that is to learn inhibits interneuron. Interneuron excites learning cell and inhibits paired cell. Paired cell inhibits interneuron and learning cell.
Associative learning requires asymmetric connections. Both main neurons inhibit interneuron, but interneuron excites learning neuron and inhibits paired neuron. Paired cell inhibits learning cell, but learning cell does not synapse on paired cell.
process: input
Association requires simultaneous stimuli to both sense cells.
process: circuit
After stimuli cease, asymmetric association-triad circuit causes signals to continue to flow around neurons, keeping learning-cell electric potential smaller. This makes it easier to stimulate learning cell.
When paired stimuli end, paired cell stops inhibiting interneuron and learning cell, so interneuron excites learning cell more. Learning cell has decreased inhibition and so inhibits paired cell even more, keeping state going until unpaired stimuli disrupt positive feedback, so neurons return to normal.
simplicity
Association nerve triad is simplest associative learning system. One neuron alone can only sensitize or desensitize itself. Two neurons can only have reverberation. No other three-neuron arrangement can make a learning circuit.
Interneuron must have inhibition by path neurons, so interneuron voltage increases when stimulation stops. Interneuron must stimulate learning cell, so learning-cell voltage increases after stimulation stops. Paired cell must inhibit learning cell, so learning-cell voltage increases after stimulation stops. Interneuron must inhibit paired cell, so, as interneuron increases voltage, paired-cell inhibition decreases.
There must be no connection from learning cell to paired cell. If there is inhibition, stimulation end increases paired-cell inhibition on learning cell. If there is excitation, stimulation end decreases inhibition, but excitation mimics stimulation, so there can be no excitation between direct paths.
There is no interneuron excitation, because stimulation end only quiets them.
uses
Association does not detect current or no current in one or the other pathway, only simultaneous inputs.
uses: negative association
If sense cell inhibits learning cell, circuit still works by positive feedback but in reverse, so voltage difference becomes more. This makes learning cell more difficult to stimulate.
uses: attention
Association allows attention-like input acknowledgement.
uses: reflex control
Reflexes receive signals from sensors and activate muscles. Association triads can control reflexes by signals from other nerve pathways or from brain.
uses: time
Association triads can detect simultaneity in time.
uses: space
Association triads can detect simultaneity in space. Time can code spatial distance.
uses: intensity
Association triads can compare intensities. Time can code intensity.
Nerve pathway {labeled-line code} itself indicates stimulus nature and spatial location.
Cortex mechanisms enhance and suppress synapses and redistribute axon terminals among receptors {neuromodulatory system}. First, synapses receive non-specific input from cholinergic and noradrenergic neurons. Later, they receive input from both body sides [Crick and Koch, 1998].
Command passes to region with the most-important information {principle of redundancy of potential command} {potential command redundancy} {redundancy of potential command}.
Cortical-neuron axons from sense brain areas can re-enter brain areas {re-entry} {re-entrant pathway}. Re-entry synchronizes and coordinates but does not provide feedback. Most nerve pathways send signals back to starting points after one or more synapses. Memory depends on brain pathways that re-excite themselves.
Control system models {Smith predictor} can predict responses if supplied with sample commands. Smith predictors combine delayed and undelayed control system models to build controller for systems with large time delays.
Nearby neurons inhibit neuron {lateral inhibition}|, to increase contrast.
Excitation tends to spread through region {spreading activation} {spreading excitation}, to link regions.
People can measure scalp electric-voltage waves {electroencephalography}| (EEG).
cause
EEG wave voltages are sums of graded potentials in dendritic trees and their synapses [Creutzfeldt and Houchin, 1984] [Creutzfeldt, 1995] [Freeman, 1975] [Mountcastle, 1957] [Mountcastle, 1998] [Remond, 1984].
EEG potential changes are larger than neuron induced activity. Potential differences between cell bodies and neuron fibers influence EEG waves. Brain potential waves imply synchronized neuron activities, over distances more than two millimeters apart. Waves are coherent, not harmonic, across different cortical areas.
location
Electric waves appear in parietal lobe, then primary motor cortex and occipital lobe, and then prefrontal lobe.
amplitude
EEG wave voltages are 1 mV to 2 mV. To detect voltage change requires averaging hundreds of measurements to subtract noise. EEG can measure scalp potential differences less than 100 microvolts [Makeig et al., 2002].
correlations
Scalp evoked-potential changes in response to image, sound, or mental event [Galambos et al., 1981].
Anesthesia and responses to simple stimulus configurations can have prolonged brain potential synchronization. Brain-potential synchronization is less during awake states and complex situations.
Waves are large in tasks requiring activity integration across different cortical areas. Waves stop at perceptual-processing conclusion and motor-signaling beginning.
Waves do not carry information about stimuli nor relate to signals from individual neurons.
correlations: awake
Hippocampus has theta rhythm at 4 Hz to 10 Hz during active movement and alert immobility, synchronized between hemispheres and 8 mm along hippocampus longitudinal axis. Awake brain has synchrony, which increases with attention and preparation for motor acts. Brain potential synchronization is less when awake.
Other behaviors have local and bilaterally synchronous rhythm near 40 Hz.
200-Hz waves correlate with alert immobility.
A 12-millisecond phase shift goes from brain rostral to caudal pole, during alpha wave activity while awake.
Most waves during waking are in posterior cortex, lower than vertex.
correlations: sleep
EEG waves can differentiate seven sleep stages. Most waves during sleeping are in vertex and frontal lobe. Synchronous firing characterizes deep sleep and epilepsy.
Between waking and sleeping, brain wave change is abrupt in adults. Between waking and sleeping, brain wave change is slow in children.
correlations: slow-wave sleep
NREM sleep has low-frequency, high-amplitude waves. Non-REM-sleep phases 3 and 4 have low-frequency EEG waves {slow-wave sleep}.
correlations: REM sleep
Awake and REM sleep activation level has high-frequency, low-amplitude waves [Hobson, 1989] [Hobson, 1994] [Hobson, 1999] [Hobson, 1999] [Hobson, 2002] [Hobson et al., 1998].
correlations: other waves
EEG waves include bereitschaftspotential, contingent negative variation (CNV), and motor potential.
factors: age
EEG-wave localization, regularity, continuity, similarity from both hemispheres, synchrony from similar areas, and stability increase until age 35. Brain-wave amplitude decreases until age 35.
Alpha waves disappear when eyes open or people have mental imagery {alpha blocking}, but some visual activities do not block alpha waves. If both visual hemispheres have damage, alpha rhythm stops.
EEG waves {alpha wave} can have frequency range 8 to 12 per second. Sleep or quiet rest has alpha waves. They have larger amplitude if brain has pathology. A 12-millisecond phase shift goes from brain rostral to caudal pole, during alpha wave activity while awake and during REM sleep [Varela et al., 2001]. Alpha-wave frequency increases until five or six years old.
Electric potentials {auditory evoked potential} (AEP) happen after sounds [Creutzfeldt and Houchin, 1984] [Creutzfeldt, 1995] [Freeman, 1975] [Mountcastle, 1957] [Mountcastle, 1998] [Remond, 1984]. Scalp electrodes can record them.
sleep
AEP during waking and REM sleep are similar but differ from AEP during non-REM sleep. Early AEP do not fluctuate during sleep-waking cycle. Early thalamocortical activity causes middle AEP, which decrease amplitude from waking to stage-4 sleep but are normal in REM sleep.
Later, AEP amplitudes decrease from waking to stage-4 sleep but increase in REM sleep. P20 component reflects cerebral-cortex activity and increases from waking to stage-4 sleep but returns to waking level in REM sleep. REM sleep does not have latest AEP: P100 wave, P200 wave, and P300 wave.
EEG waves {beta wave} can have frequency range 15 Hz to 25 Hz. Beta-wave frequency increases until 15 years old.
EEG {bispectral index} can measure anesthesia depth.
EEG waves {delta wave} can have frequency range 1 Hz to 4 Hz. If sound is during REM-sleep delta-wave activity, no coherent 40-Hz oscillations begin [Creutzfeldt and Houchin, 1984] [Creutzfeldt, 1995] [Freeman, 1975] [Mountcastle, 1957] [Mountcastle, 1998] [Remond, 1984]. Delta-wave frequency increases until one year old.
Scalp potential {evoked potential} {event-related potential} changes in response to image, sound, or mental event [Galambos et al., 1981].
Concentrating on probable signal arrival changes electroencephalograph potential {expectancy wave} (e-wave).
Awake but non-attentive animals have large-amplitude synchronized 25-Hz to 35-Hz oscillations {gamma wave} [Engel and Singer, 2001] [Keil et al., 1999] [Klemm et al., 2000] [Revonsuo et al., 1997] [Rodriguez et al., 1999] [Tallon-Baudry and Bertrand, 1999].
locations
Visual precentral and postcentral cortex, retina, olfactory bulb, thalamus, other brain nuclei, and cerebral neocortex have continuous and coherent 30-Hz to 70-Hz {40-Hz oscillation} electric potential oscillations.
All visual areas and both hemispheres synchronize cells. Visual field feature produces coherent 40-Hz oscillations separated by as much as 7 mm in visual cortex [Eckhorn et al., 1988] [Eckhorn et al., 1993] [Engel et al., 1990] [Friedman-Hill et al., 2000] [Gray and Singer, 1989] [Kreiter and Singer, 1992] [Ritz and Sejnowski, 1997].
Somatosensory and motor cortex potentials synchronize while thinking but vanish during actual movement.
cause
40-Hz oscillations happen when cells in different cortex or thalamus parts respond to linked stimulus parts [Crick and Koch, 1990] [Engel and Singer, 2001] [Metzinger, 2000].
attention
Oscillations synchronize more during focused attention [Mountcastle et al., 1981] [Wurtz et al., 1982].
induced gamma wave
When people perceive object with coherent features, 30-Hz EEG wave starts in occipital cortex 200 ms after stimulus and dies out after perceptual processing.
People can measure magnetic fields caused by brain electric currents {magnetoencephalography} (MEG), using superconducting quantum interference devices (SQUID).
When people make or observe voluntary movement, EEG waves {mu wave} {µ wave} decrease. Mirror neuron activity blocks mu waves.
EEG waves {N400 wave} can be about semantic improbability, as opposed to semantic relatedness.
260 ms to 500 ms after rare stimuli, attention to object to recognize it or use it causes 40-Hz oscillations {P300 wave}, which correlate with event unexpectedness.
If people are conscious or dreaming, high-amplitude electrical waves {PGO wave} arise in pons, radiate to geniculate body, and then go to occipital cortex. Saccadic eye movements cause potential waves in cholinergic neurons in pons and go to lateral geniculate nucleus and occipital cortex. Signals from aminergic cells inhibit cholinergic neurons. PGO waves accompany desynchronization.
0.8 second earlier than planned voluntary movement, ipsilateral motor cortex EEG changes potential {readiness potential} to negative. Conscious willing feeling is later. 0.5 second earlier than unplanned voluntary movement, EEG changes potential to negative. Perhaps, consciousness can still stop or allow action before it has begins [Libet, 1993] [Libet et al., 1999]. Lateralized readiness potential is in contralateral cortex and happens after action selection.
For activation, awake stage and REM sleep has high-frequency low-amplitude EEG waves. NREM sleep has low-frequency high-amplitude EEG waves. Stage II NREM sleep has distinctive EEGs {sleep spindle} {K-complex wave}.
EEG waves {theta wave} in hippocampus can have frequency range 4 Hz to 8 Hz [Buzsáki, 2002] [Kahana et al., 1999] [Klimesch, 1999] [O'Keefe and Recce, 1993]. Theta-wave frequency increases until two to five years old. REM sleep has theta waves in hippocampus.
Treatments {Transcranial Magnetic Stimulation} (TMS) can excite or inhibit brain regions to treat depression, obsession, stress, and mania [Cowey and Walsh, 2001] [Kamitani and Shimojo, 1999].
Brain evolved {brain, evolution}.
brain: parts
Brain is an enlargement and opening of spinal cord cranial end. First, slight enlargement formed rhombencephalon. Then, pons (bridge) evolved. Rhombencephalon evolved to myelencephalon and metencephalon. Above pons and further forward, rostrally towards nose, is mesencephalon. From midbrain roof, special motor cerebellum evolved, first becoming large and important in birds. Fourth-ventricle top became midbrain cerebral aqueduct. Rostral to midbrain is forebrain, with diencephalon and telencephalon [Cummins and Allen, 1998].
brain: processes
Neural structures evolved first reflexes, then associations, then feature surfaces and flows, then objects and events, then scenes and trajectories, and then histories and stories over space and time using language [Cummins and Allen, 1998].
brain: tissue
Neural tissue evolved from neuron to interneuron, ganglion, ganglia group, cortex, two-layer paleocortex, four-layer neocortex, and six-layer frontal lobe cortex.
design
Neural tissue and brains evolved opportunistically and did not follow design. Brains are not evolving teleologically to defined final state. Brains do not necessarily work efficiently.
motion
Originally, sensation led directly to motion. Brain evolved to separate perception from motion. Brain further evolved to integrate perception, memory, emotion, and goals. Brain then evolved to have consciousness.
Mammalian cortex has both caudal and rostral reciprocal pathways {dual origin hypothesis}. Birds have hyperstriatum and neostriatum. Hyperstriatum evolved like mammalian cortex. Neostriatum evolved from DVR.
pallium
Top and bottom cerebral neocortex layers are homologous to pallium. Reptile medial pallium evolves to mammal hippocampus major and subiculum. Reptile lateral pallium evolves to mammal olfactory cortex. Pallium receives from olfactory and limbic cortex, caudally.
ventricular ridge
Middle four cerebral neocortex layers are homologous to reptile dorsal ventricular ridge. Dorsal ventricular ridge receives from within itself, rostrally.
Reptiles have dorsal cortical plate {pallium}.
Reptiles have a two-layer ridge {ventricular ridge} {dorsal ventricular ridge} (DVR) behind brain ventricles.
Enlargement and opening of spinal-cord cranial end at hindbrain was earliest brain {rhombencephalon}|.
Rhombencephalon evolved to medulla oblongata {myelencephalon}|, in hindbrain.
Above pons and further forward, rostrally towards nose, is midbrain {mesencephalon}|.
Rhombencephalon evolved to medulla, cerebellum, pons, mamillary bodies, pituitary gland, and habenula {metencephalon}|, in hindbrain.
Brain regions {rhinencephalon}| {smell brain, rhinencephalon} can be near frontal lobe.
Rostral to midbrain are epithalamus, fornix, hypophysis, hypothalamus, subthalamus, thalamus, and third ventricle {diencephalon}|, in cerebrum and forebrain. All diencephalon regions connect to each other and to cerebral cortex.
Rostral to midbrain are cerebral cortex, white matter, and basal ganglia {telencephalon}|. Cerebral cortex has frontal, parietal, temporal, occipital, insular, and limbic lobes.
evolution
In amphibians, dorsal telencephalon became dorsal cortex and hippocampus. Medial telencephalon became septum, which connects to hippocampus. Lateral telencephalon did nothing, because amphibians have no dorsal ventricular ridge. Ventral telencephalon became striatum, for muscle control.
In reptiles, dorsal telencephalon became dorsal cortex and hippocampus. Medial telencephalon became septum. Lateral telencephalon became dorsal ventricular ridge, for senses and/or emotions. Ventral telencephalon became striatum.
In birds, dorsal telencephalon became hyperstriatum with wulst. Medial telencephalon became septum. Lateral telencephalon became dorsal ventricular ridge. Ventral telencephalon became striatum.
In mammals, dorsal telencephalon became cerebrum, including neocortex and hippocampus. Medial telencephalon became septum. Lateral telencephalon became laterobasal amygdala for emotions. Ventral telencephalon became striatum.
Bottom brain has eight repeated parts {rhombomere}, with one next to cerebellum and eight near spinal cord. Cells do not migrate from one rhombomere to another. Eighth cranial nerve comes from fourth rhombomere.
Low brain part {lower brain} includes medulla oblongata, pons, and cerebellum.
Above spinal cord, bottom brain {hindbrain}| is medulla oblongata then pons.
Above pons and further forward, rostrally towards nose, are cerebellar peduncles, inferior olive, quadrigeminal plate, nucleus accumbens, red nucleus, substantia nigra, tectum, and midbrain tegmentum {midbrain}|. All midbrain nuclei have ascending and descending axon tracts. Midbrain is for attention, controls aggressiveness, and predicts adjustments to visual perception that will result from movement, using signal {central kinetic factor} that codes displacement direction and speed.
Rostral to midbrain are cerebral-cortex frontal, parietal, temporal, occipital, insular, and limbic lobes, white matter, and basal ganglia {endbrain}.
Front brain {forebrain}| contains cerebrum diencephalon and telencephalon: amygdala, basal ganglia, cortex, hippocampus, olfactory bulb, and thalamus.
At fourth ventricle, above spinal cord, brain regions {brainstem}| can have cervical flexure and cephalic flexure and contain midbrain and hindbrain [Parvizi and Damasio, 2001] [Zeman, 2001]. Brainstem includes cranial nerve nuclei.
hindbrain
Hindbrain contains pons near midbrain and medulla oblongata near spinal cord.
midbrain
Midbrain has noradrenergic lateral reticular system, noradrenergic locus coeruleus, serotoninergic raphe nucleus, dopaminergic basal midbrain nuclei, cholinergic sense nuclei, and histaminergic nuclei.
Histaminergic nuclei project in net over brain.
Cholinergic sense nuclei connect to cerebral cortex. Damage reduces cerebral activity and causes a dreamy state.
functions
Brainstem integrates signals for attention, sex, and consciousness. Consciousness requires higher brainstem.
Regions {area postrema} can lack blood-brain barrier and can sense large molecules.
Forward brainstem {basal forebrain}| damage affects event-time recall.
Brainstem nucleus {cochlear nucleus} receives from cochlea hair cells.
Brainstem nucleus {lateral cervical nucleus} sends to superior colliculi.
Brainstem nucleus {nucleus sagulum} sends to superior colliculi.
Brainstem nucleus {perihypoglossal nucleus} sends motor input to superior colliculi.
In vertebrates other than mammals, structure {poker chip} decides which of twenty behavior modes is most appropriate. Poker chip later evolves to become reticular formation.
Brainstem nucleus {posterior commissure nucleus} sends motor input to superior colliculi.
Brainstem nucleus {prepositus hypoglossius} receives from superior colliculi and sends to oculomotor system.
Mesencephalic reticular formation, intralaminar nuclei, and reticular nuclei {reticular formation}| {reticular activating system} {reticulum} {ascending reticular activating system} {extralemniscal system} {non-specific afferent system} {gating system} {ascending activation system} {midbrain reticular formation} {mesencephalic reticular formation} stimulate thalamus and cortex to cause waking and sleep states.
purposes
Reticular formation arouses, integrates signals, maintains consciousness, controls vital functions, modulates perception, forms and recalls memories, and coordinates motor behaviors.
purposes: consciousness
Consciousness involves thalamus reticular-activating-system ascending fibers.
damage
Damage to reticular formation causes coma, memory disorganization, sleep, reduced cortex energy, similar reactions to strong and weak stimuli, and poor behavior control.
electrical stimulation
Reticular-formation electrode stimulation can cause unpleasant feelings.
electrical stimulation: memory
Retention improves with reticular formation stimulation, which arouses brain. Stimulation does not affect retrieval. Stimulating other brain areas has no affect on retention.
biology: input
Reticular formation receives axons from sense pathways and cortex and has multisensory convergence sites. All senses activate ascending reticular formation, which mediates pain. Stimulating ascending reticular formation causes fear and avoidance behaviors.
biology: output
Interconnecting neurons with short axons run from lower brainstem to midbrain. Descending reticular formation acts on interneurons indirectly.
biology: chemicals
Serotonin affects reticular formation and attention system to synchronize cortex. Noradrenaline desynchronizes cortex.
biology: columns
Reticular formation has medial, median, and lateral columns, from anterior midbrain through pons, medulla, and spinal cord [Hobson, 1989] [Hunter and Jasper, 1949] [Magoun, 1952] [Moruzzi and Magoun, 1949] [Steriade and McCarley, 1990].
Medial column receives pyramidal tract, cerebellum, and sense axons from cortex and sends by ascending reticular activating system to intralaminar thalamic nuclei, which send to striatum and cortex, to activate cortex and control waking and sleeping.
Raphe nucleus median column, mainly dorsal raphe nucleus, sends inhibition to limbic system in median column.
Lateral reticular system for attention projects to spinal cord, hypothalamus, and brainstem lateral-column tractus-solitarius nucleus. Noradrenaline locus coeruleus lateral column sends attention information to limbic system and prefrontal lobes.
biology: evolution
Reticular formation is only in mammals but evolved from something similar in lower animals.
Brainstem nucleus {solitary tract nucleus} {tractus solitarius nucleus} receives from locus coeruleus, trigeminal nucleus, and vagus nerve and sends to parabrachial nucleus, which receives from GI tract, and ventral medial basal thalamus. Solitary tract nucleus, with taste cortex and thalamus, is for taste preferences and can detect nausea. NTS is satiation region and receives gut peptide cholecystokinin (CCK).
Brainstem nucleus {trigeminal nucleus} receives sensory C fibers and A-delta fibers caudally from spinal cord posterior horn lamina I and sends to ventral medial posterior thalamus, brainstem nucleus tractus solitarius, and brainstem parabrachial nucleus.
Brainstem nuclei {vestibular nucleus} can be for balance.
Brainstem regions {zona incerta} can send motor input to superior colliculi.
Ascending reticular-activating-system (ARAS) lowest-hindbrain component {sensory reticular formation} receives visceral, somatic, auditory, and visual axons from ascending sense axons and sends to neocortex through hypothalamus and thalamus. It has pain center and wakefulness or alertness center.
Spinal-cord brainstem bulb {medulla, brain}| {medulla oblongata} includes basal ganglia and continues major nerve tracts. It relays auditory nerve sense and motor nerves, mediating phonation and articulation. It regulates cardiac action, chewing, tasting, swallowing, coughing, sneezing, salivation, vomiting, and sucking in newborns. Respiratory center maintains respiration. Some medulla-oblongata neurons make epinephrine.
A limbic-system part {amygdala}| includes insula white matter.
location
Insula is in posterior frontal lobe and anterior temporal lobe.
input
Lateral amygdala receives sensations slowly from sensory cortex and fast from thalamus, and receives memories from medial temporal lobe. Central amygdala receives from lateral amygdala, prefrontal cortex, and basal amygdala. Basal amygdala receives from lateral amygdala, medial temporal lobe, and prefrontal cortex.
output
Amygdala dopamine neurons connect to cholinergic neurons in medial septal nucleus, nucleus accumbens, nucleus basalis magnocellularis, nucleus of diagonal band of Broca, hypothalamus regions for motivation and reward, and sense and motor cerebral cortex upper layers.
Amygdala sends to orbitofrontal prefrontal cortex, mediodorsal thalamic nucleus, and hippocampal formation.
Lateral amygdala sends to central amygdala. Central amygdala sends to lateral hypothalamus for blood pressure, paraventricular hypothalamus for hormones, motor cortex for stopping, and basal amygdala. Basal amygdala sends to central amygdala.
functions
Amygdala compares new stimulus to previous stimuli and signals differences to other brain regions. Using memory, amygdala participates in habituation and anticipation.
Amygdala {basolateral nucleus} affects aggression, dominance, submission, and territoriality behaviors. Amygdala regulates fear and emotional behavior. Amygdala regulates visceral activity. Amygdala affects vision and smell.
damage
Removal of, or injury to, amygdala does not affect memory.
drug
Cocaine affects sublenticular extended amygdala.
Medulla ganglia {basal ganglia}| include amygdala, caudate nucleus, claustrum, external-capsule fibers, globus pallidus, internal-capsule fibers, lentiform nucleus, nucleus basalis of Meynert, nucleus dorsalis, putamen, septal nuclei, substantia nigra pars reticulata, and subthalamic nucleus.
input
Basal ganglia receive from basal-midbrain-nuclei dopaminergic neurons.
output
Basal-ganglia cholinergic neurons send to motor cortex for transmission to muscles [Langston and Palfreman, 1995].
functions
Basal ganglia assemble, select, and trigger automatic movements, perceptual motor coordination, ballistic movements, and proprioceptively controlled movements, using movement plans. They track moving visual objects, control eye movements, and process visual and multisensory data. They control tremor and muscle tone. Basal ganglia coordinate with neocortex and cerebellum for posture and complex voluntary movements.
Medulla basal ganglia {caudate nucleus} can inhibit globus pallidus. Caudate nucleus receives excitatory input from cerebral cortex and inhibitory input from thalamus, substantia nigra, and raphe. Caudate nucleus is for memory and obsessive behavior.
Medulla basal ganglia {claustrum} can lie under cerebral cortex near insula and project to many cortex regions.
Putamen and globus pallidus {lenticular nuclei} look striated because they have myelinated tracts.
Brainstem regions {motor reticular formation} can facilitate spinal mediated reflexes and transmit feedback from higher centers to primary receptors.
Basal ganglia nuclei {nucleus basalis of Meynert} {nuclei of Meynert} {Meynert nuclei} {substantia innominata} can have cholinergic neurons and send to cerebral cortex.
Basal ganglia nucleus {nucleus dorsalis} receives proprioception input from spinal cord.
Brainstem regions {globus pallidus} {pallidum} can receive from red nucleus and inhibit thalamus and subthalamic nucleus. Dopamine neurons can cause rigidity if overstimulated. Choline neurons can cause hyperkinesis, chorea, and athetosis if overstimulated.
Basal ganglia connect to thalamus, then to cortex, then back to basal ganglia {polysynaptic loop}.
Medulla basal ganglia {putamen} can receive excitatory input from cerebral cortex and inhibitory input from thalamus, substantia nigra, and raphé nucleus. It inhibits globus pallidus. Putamen is for memory, motor skill, and obsessiveness. It has nearby-space maps, used in motor control.
Brainstem regions {raphé dorsalis} can send motor input to superior colliculi.
Medulla nuclei {raphé nuclei} can secrete serotonin, make peptide substance P, start light sleep, and modulate pain, using spinal-cord dorsal-horn presynaptic inhibition.
Forebrain basal ganglia {septal nuclei} {septum, medulla} can receive from hippocampus and reticular formation and send to hippocampus, hypothalamus, and midbrain. Septal nuclei have trophotropic centers. They can control aggressiveness. They organize sexual thoughts, emotions, and action. They are in or near region that causes pleasure when excited.
Putamen, globus pallidus, and caudate nucleus {corpus striatum} {striatum} are near thalamus. They look striated because they have myelinated tracts.
no layers
Corpus striatum neuron types mix but not in layers.
maps
Most maps in mammalian cortex connect to maps in corpus striatum.
functions
Corpus striatum integrates learned automatic movement sequences, such as voluntary eye movements.
input
Some striatum neurons receive from thousands of cortical neurons that send 10-Hz to 40-Hz oscillating signals {interval timer}. Stimuli synchronize oscillations. Oscillators then go on oscillating. Second stimuli make substantia nigra send dopamine to striatum. Striatum remembers signal pattern. If starting signal repeats, dopamine repeats.
output
If pattern matches, striatum signals to thalamus, which informs cortex.
Medulla regions {respiratory center} can send excitatory signals along phrenic nerve to diaphragm.
Nuclei {subthalamic nucleus} {Luys nucleus} {Luys body} {nucleus of Luys} {body of Luys} can be near hypothalamus, inhibit globus pallidus, and send to thalamus. Damage causes ballistic movement.
Fiber bridge {pons}| from hindbrain side to opposite cerebellum side holds major nerve tracts connecting cerebellum and cortex, in both directions, and connects thalamus to olive. Cerebral cortex motor regions influence pons. Pons controls heart, lungs, eye movements, muscle tone, walking, and running. It mediates protective and orientation reflexes.
A pons region {locus coeruleus}| can receive feedback from sense cortex and send to spinal cord, hypothalamus, tractus solitarius nucleus, sensory cerebral cortex, and cerebellum Purkinje cells [Foote and Morrison, 1987] [Foote et al., 1980] [Hobson, 1999]. Locus coeruleus contains few thousand neurons and is largest noradrenaline nucleus.
transmitters
Locus-coeruleus neurons contain neuropeptide Y (NPY) and galanin peptide transmitters.
functions
Locus coeruleus suppresses tonic vegetative regions. It regulates attention, pleasure, energy, motivation, and arousal. It causes deep sleep. REM sleep, cataplexy, grooming, and feeding depress it. Interruptions and multimodal somatosensory stimuli, including pain, excite it. Locus-coeruleus electrical stimulation causes fear and anxiety.
A pons region {pneumotaxic center} receives from nerves that sense alveoli stretching and inhibits breathing.
A pons regions {tegmentum} can include reticular formation and be for attention.
Midbrain ganglia {cuneate nuclei} can receive texture, form, and vibration information in medulla ipsilateral cuneate tracts and send to thalamus, cerebrum, and cerebellum. Maps are smaller than in other areas.
Midbrain nuclei {gracile nuclei} can receive texture, form, and vibration information in medulla ipsilateral gracile tracts and send to thalamus, cerebrum, and cerebellum. Maps are smaller than in other areas.
Midbrain nuclei {inferior colliculi} can send to superior colliculi. They have auditory functions and control eye movements.
Brainstem regions {inferior olive} (IO) can send to cerebellar Purkinje cells.
Midbrain striatum nucleus {nucleus accumbens} receives excitatory dopaminergic pathway from frontal lobes and ventral tegmentum and receives from basal and lateral amygdala. It sends to ventral pallidum. Nucleus accumbens mediates emotions and movements. Benzodiazepine anti-anxiety agent and antipsychotic agents block dopaminergic pathway activation. Regular drug use and other reward stimuli increase delta FosB transcription factor, which causes sensitization and degrades slowly, in nucleus accumbens.
Vertebrates other than mammals have vision cell layer {optic tectum} over large ventricle. Mammals have superior colliculi instead. In amphibia and fish, fibers from retina to tectum keep growing and changing. Mostly unimodal sense pathways go from cerebral cortex to tectum. Tectum makes eye saccades to focus attention-getting object on fovea. Divergence in individual tectum-nuclei loops explains how large recruited tectum-neuron population can form composite command observed at tectum.
Posterior upper brainstem region {parabrachial nuclei} (PBN) receives from sensory trigeminal nucleus and nucleus tractus solitarius and sends motor input to superior colliculi and motor output to hypothalamus and ventral medial basal thalamus.
Pons and thalamus nucleus {periaqueductal gray} (PAG) has opiate receptors and makes endorphins.
Brainstem nucleus {periolivary nucleus} near olive sends to superior colliculi.
Brainstem regions {posterior upper brainstem} can contain periaqueductal gray, parabrachial nucleus, monoamine nuclei, and acetylcholine nuclei. Damage to posterior upper brainstem causes coma.
Brainstem regions {quadrigeminal plate} can have superior and inferior colliculi.
Brainstem nucleus {red nucleus} {ruber nucleus} receives from amygdala and sends to hypothalamus paraventricular nucleus {stria terminalis}. It works similarly to motor cortex.
Brainstem regions {substantia nigra} {substantia nigra pars reticulata} can send to superior colliculus to control eye movement. Substantia nigra cholinergic neurons connect to sense and motor neurons in caudate nucleus and putamen in basal ganglia. Basal ganglia and other midbrain dopamine neurons inhibit caudate nucleus, corpus striatum, and thalamus to coordinate motor function and automatic movement. Alzheimer's disease degenerates substantia nigra neurons.
Mammal midbrain dorsal surface has large symmetrical bumps {superior colliculi} that mediate light accommodation, eyeball movements, body movements for vision, orientation, and attention [Aldrich et al., 1987] [Brindley et al., 1969] [Celesia et al., 1991].
anatomy
Superior colliculus has seven alternating cellular and fibrous layers with few interneurons, eight types of synaptic terminals, and broad dendrite arbors. Superficial layers I to III and deep layers IV to VII have topographic motor maps and associated visual and touch maps.
Superior colliculus removal causes failure to detect contralateral visual stimuli.
anatomy: input
Superior colliculus efferent neurons for eye movements receive input from substantia nigra.
Superior colliculus deep layers receive vision information ipsilaterally from lateral suprasylvian visual area and anterior ectosylvian visual area, not from striate visual cortex.
Deep layers receive somatosensory input from anterior ectosylvian sulcus dorsal part, contralateral sensory trigeminal complex, dorsal column nuclei, lateral cervical nucleus, and spinal cord. Contralateral sensory trigeminal complex receives C fibers and A-delta fibers.
Deep layers receive auditory input from anterior ectosylvian sulcus Field AES region, inferior colliculus contralateral brachium, inferior colliculus external nucleus, nucleus sagulum, and dorsomedial periolivary nucleus.
Deep layers receive motor input from frontal eye fields, motor cortex, zona incerta, thalamus reticular nucleus, posterior commissure nucleus, perihypoglossal nucleus, contralateral superior colliculus, locus coeruleus, raphé dorsalis, parabrachial nuclei, reticular formation, and hypothalamus.
Deep layers receive from basal ganglia through substantia nigra pars reticulata. Deep layers receive from cerebellum deep nuclei, including medial and posterior interposed nuclei.
anatomy: output
Superior colliculus deep layers send to thalamus, opposite superior colliculus, brainstem, and spinal cord. Superior colliculus deep layers connect to sense and motor cerebral cortex and to brainstem and spinal cord, to position peripheral sense organs. Deep layers also send contralaterally to tegmentum and spinal cord to reposition eyes, head, limbs, ears, and whiskers.
neurons: receptive field
Superior-colliculus neurons have central ON zones surrounded by lower sensitivity areas, not like retina and lateral-geniculate-nucleus ON-center-neuron or OFF-center-neuron receptive fields. Receptive fields are larger than in lateral geniculate or cortex neurons. Border is inhibitory {suppressive zone}. The most-effective stimulus is smaller than receptive field. Moving or flashing stimuli are more effective than stationary ones. Movement direction is more effective. Slow movements are more effective than rapid ones. Repeating same stimulus produces response habituation.
neurons: noxious
Superior colliculus neurons {nociceptive-specific neuron} (NS) can respond to noxious stimuli. Superior colliculus neurons {wide dynamic range neuron} (WDR) can respond to all mechanical stimuli, but especially to noxious mechanical or thermal stimuli.
neurons: multisensory
Superior colliculus neurons are 25% unimodal and 75% multisensory. Multisensory and unimodal neurons typically require 100 milliseconds to process information, but some multisensory neurons take 1500 milliseconds.
neurons: auditory
Superior colliculus has four auditory neuron types. Compared to cortical auditory neurons, superior colliculus auditory neurons are more insensitive to pure tones and more sensitive to spatial location, interaural time, and intensity differences. They respond better to moving stimuli, have directional selectivity, habituate to repeated stimuli, and have restricted receptive fields with maximal-response regions.
neurons: somatosensory
Superior colliculus somatosensory neurons respond to hair or skin stimulation, have well-defined receptive fields, prefer intermediate-velocity or high-velocity stimuli, habituate rapidly, are large, have best regions, have no inhibitory surrounding areas, and have no directional selectivity.
neurons: movement field
Midbrain neuron receptive fields {movement field} are like sense-neuron receptive fields. Neurons with similar movement fields are in same superior colliculus region. If neuron activity exceeds threshold, amount above threshold determines saccade movement velocity and distance.
eye movement
Mammal superior colliculi and non-mammal optic tectum process multisensory information, shift attention, and control voluntary and involuntary eye and other sense-organ movements, for orientation and attention. Stimulation shifts eyes, ears, and head to focus on stimulus location. High intensity causes withdrawal or escape.
Anteromedial superior colliculi stimulation causes contralateral, upward, and parallel conjugate eye movement.
Lateral superior colliculi stimulation causes conjugate, contralateral, and downward movement.
To initiate eye movement to periphery, caudal superior colliculus, which represents peripheral visual space, has pre-motor activity.
Visual fixation involves neurons in rostral superior colliculus.
eye movement: saccade
Superior colliculus neurons {motor error neuron} can generate low-frequency, long-duration discharge to signal difference between current eye position and target position. Superior colliculus neurons can initiate saccades and determine speed, direction, and amplitude [Corbetta, 1998] [Schall, 1991] [Schiller and Chou, 1998]. Saccade initiation and velocity, duration, and direction specification are separate processes. Saccade commands are many-neuron vector sums.
Brainstem regions {superior olive} can measure time and intensity differences to differentiate auditory-signal arrival times. Olive sides {lateral superior olive} (LSO) receive inputs from both ears for intensity-level-difference detection. Olive middle {medial superior olive} (MSO) receives inputs from both ears, for time-difference detection. Neurons have time-difference ranges.
Brainstem region {ventral tegmentum} {ventral tegmental area} (VTA) is for pleasure and motivation. Dopamine neurons inhibit nucleus accumbens, mesolimbic system, frontal cortex, and sensorimotor cortex.
Cerebellar cortex {cerebellum}| is for smooth, continuous, and rapid movement. Cerebellar activity is never conscious. Peripheral vision, cerebellum, and vestibular system find body positions.
functions
Cerebellum maintains balance, posture, equilibrium, and muscle tone. It sets appropriate voluntary-muscle motor control, rates, forces compared to resistance, movement directions, and coordination.
functions: comparator
Cerebellum works as comparator. Motor cortex sends to spinal cord to initiate voluntary actions and to cerebellum to inform about intended movements. Proprioceptive nerve input goes to cerebral cortex and then to cerebellum to report actual movements. Cerebellum sends to motor cortex and spinal cord to correct movements.
functions: damping
Damping involves inhibiting agonist and antagonist contractions to eliminate muscle tremor, for smooth movement.
functions: error control
Error control involves initial strong muscle contraction and subsequent antagonist-muscle contraction.
functions: feedforward
Sense delays prevent feedback alone from controlling fast and accurate biological movements. Cerebellum uses predictive, feedforward control.
functions: gain
Perhaps, cerebellum controls amplification gain in spinal and brainstem reflexes. Cerebellum can subtract adjustable signal from fixed-gain saccadic circuit.
functions: precision
Cerebellum compares sense stimuli about actual performance with movement program received from cerebrum, measures error, and corrects movement. For example, it regulates smooth eye movements by tuning reflexes using Purkinje cells.
It regulates premotor networks by inhibiting and disinhibiting motor-control actions that begin in brainstem, sensorimotor-cortex, and spinal-cord premotor networks. To control movement, Purkinje cells first exert increased inhibition on deep nuclei excited by cerebral cortex and sense information. Then, inhibition decreases, and deep nuclei send excitatory output to pons and red nuclei, which send to motor cortex.
functions: prediction
Prediction involves comparing information received from eyes, body, and cerebrum, to calculate when to slow and/or stop motion.
functions: progression
Progression involves muscle contraction in sequence, to coordinate and time.
functions: sensation
Cerebellum coordinates information from different senses. Skin touch receptors send to separate cerebellum areas. Cerebellum reacts more quickly to auditory stimulus than visual stimulus. Cerebellum reacts faster to higher intensity and multiple sensory stimuli.
Cerebellum affects sense accuracy, sense quickness, sense timing, short-term memory, attention, emotions, and planning. Lateral cerebellum affects perception, pattern recognition, and cognition.
functions: timing
Perhaps, cerebellum is for timing. Perhaps, parallel fibers are delay lines, and climbing fibers are clock read-out mechanisms. When parallel fiber and climbing fiber activation coincide, Purkinje cells fire to activate antagonist muscles and stop movements at intended targets.
One climbing fiber synapses on one Purkinje cell. Perhaps, cerebellar clock activates proper Purkinje-cell assemblies at right time.
learning
Cerebellum learns movement timing and guides learning in deep nuclei. It stores learned-skill model or memory within six hours, so skill becomes automatic.
learning: long-term depression
Increased dendritic calcium concentration induces cerebellar long-term depression (LTD). Cerebellar LTD reduces excitatory input to Purkinje cell. LTD can decrease synaptic weights, using climbing fiber input as training signals, Purkinje cell firing as postsynaptic factor, and/or parallel fiber synaptic activity as presynaptic factor. LTD at basket-cell and stellate-cell spiny synapses maintain excitatory input to Purkinje cells [Eccles et al., 1976].
cells: basket cell
Basket cells lie in Purkinje cell dendrites.
cells: flocculus neuron
Flocculus neurons send corrective signals for movements.
cells: Golgi cell
Golgi cells lie in middle layer between Purkinje cells.
cells: granule cell and parallel fiber
Granule cells are small neurons, have high density, and are the most common. Granule-cell-axon parallel fibers pass through middle layer, contacting one Purkinje cell many times, to outer layer, where they split, form straight line, and extend horizontally through outer layer. Parallel fiber is perpendicular to hundreds of Purkinje cell dendrite trees and contacts each once.
cells: Purkinje cell
Purkinje cells are large neurons that have tree-shaped flat dendrite planes, which converge onto one trunk into Purkinje cell. Purkinje cell membrane has 150,000 synapses, ten times more than other neuron types, mostly from granule cells. Purkinje cell axons inhibit Golgi cells and granule cells in cerebellar nuclei, which send axons to brain pyramidal and extrapyramidal tracts.
cells: stellate cell
Stellate cells lie beside Purkinje cell dendrites and have fibers that run horizontally through outer layer, mainly through one Purkinje cell dendrite tree.
biology
Cerebellum anatomy is the same in all vertebrates. Cerebellum has surface area equal to one cerebral hemisphere. It has more than half of all brain neurons. It has more folding than cerebrum.
Low-threshold cerebellar receptive fields and neurons align with nociceptive punishment signal fields and neurons.
biology: damage
Cerebellum damage decreases muscle tone, causes slowing and trembling, and fails to stop movements on time. One-side damage causes flexion on one side and extension on other. Within 45 minutes, cutting spinal cord stops flexions and extensions. Cutting after 45 minutes does not stop flexions and extensions. Cerebellum damage in early life does not affect behavior.
biology: evolution
During human evolution, cerebellum expanded at same rate as cerebrum.
biology: input
Sensory cerebellum receives tactile, visual, and auditory nerves. Cerebellum lobes have body-surface tactile representations.
biology: output
Motor cerebellum has reverberatory circuit to higher motor centers, regulates voluntary movements, organizes somatotopically, and has archicerebellum and neocerebellum. Motor cerebellum maintains muscle tonus, posture, and equilibrium.
biology: waves
Cerebellum has electrical waves lasting 150 to 200 milliseconds, at 0.02 mV to 0.12 mV.
biology: layers
Inner deep granule-cell layer has closely packed granule cells, as well as scattered Golgi cells that inhibit nearby granule cells. Middle Purkinje-cell layer has one Purkinje-cell row, surrounded by smaller basket cells. Wide outer-molecular layer has Purkinje cell dendrites that spread in plane and stellate cells that contact dendrites.
biology: pathways
Cerebellum receives excitatory input from vestibular-system mossy fibers or pons climbing fibers. Mossy fibers from vestibular system synapse with Golgi cells and granule cells. Mossy fibers from Golgi cells and granule cells send to Purkinje cells and process intersensory information. Pons climbing fibers synapse with granule, Golgi, Purkinje, basket, and stellate cells. Purkinje cells inhibit Golgi cells and granule cells.
biology: peduncles
Cerebellum attaches to posterior brainstem by three pairs of stalks {cerebellar peduncle}, which contain both afferent and efferent nerve fibers. Superior, middle, and inferior tracts join cerebellum to midbrain. Tract {superior peduncle} comes from neocortex. Tract {middle peduncle} {brachium pontis} comes from pons. Tract {inferior peduncle} comes from inner-ear vestibular apparatus.
biology: hemispheres
Cerebellum has two lateral parts {cerebellar hemisphere}, which have many small folds {folia}, connected by thin central worm-shaped part {vermis}. Vermis has inferior part that controls gross motor coordination and superior part that controls fine motor coordination. Gray-matter outer cover {cerebellar cortex} is over white matter {medullary body}.
biology: nuclei
Four deep nuclei are in cerebellar white matter. All vertebrates have the oldest cerebellum part {archicerebellum} {vestibulocerebellum}, in center {flocculus} {nodule, cerebellum}, which has afferent and efferent connections in inferior peduncle, mainly with inner-ear vestibular semicircular canals {maculae}. Cerebellum has small inferior portion {flocculonodular lobe}, for balance, position, head position changes, acceleration, deceleration, and angular movements. Fibers from retina, eye movement nuclei, and cortex terminate in vestibulocerebellum. The second oldest part {paleocerebellum} {spinocerebellum} corresponds to anterior lobe and posterior vermis and receives touch, pressure, thermal, and proprioceptive input from inferior-peduncle ascending spinal-cord and brainstem pathways. Skin, muscle, and tendon receptors send performance information about rate, force, and movement direction, especially propulsive movements such as walking and swimming.
Perhaps, cerebellum has static associative memories {Cerebellar Model Articulation Controller} (CMAC) that implement locally generalizing non-linear maps between mossy-fiber input and Purkinje-cell output. Granule and Golgi cell-network association layer generates sparse expanded mossy-fiber-input representations. Adjustable weights couple large parallel fiber vector to Purkinje-cell output units with graded properties.
pattern
Adjustable pattern generator (APG) model can generate elemental burst command with adjustable intensity and duration. It models positive feedback between cerebellar nucleus cell and motor cortical cell.
Excitatory input {climbing fiber} from inferior olive goes to one Purkinje cell, making 300 synapses, to fire Purkinje cell. Perhaps, climbing fiber makes error-and-training signals to adjust parallel-fiber synaptic weights, teaching Purkinje cells to recognize patterns signaled by input vectors and to select movements that reduce errors. Perhaps, cerebral cortex activates climbing fiber input, to train cerebellum to recognize appropriate contexts for generating same movements more automatically.
Inferior-olive small neuron clusters, with similar receptive fields, stimulate parasagittally-oriented cerebellar Purkinje-cell strips, which send to cerebellar nuclear-cell common cluster {microzone}.
Spinal-cord and brainstem excitatory axons {mossy fiber} synapse on more than 40 granule-cell glomeruli and deep-cerebellar nuclei. Mossy fiber also directly contacts 250 Purkinje cells but cannot fire them. Mossy fiber influences 200,000 Purkinje cells. Mossy fibers have sensory properties, but Purkinje and nuclear cells do not respond to somatosensory stimulation.
The newest and largest cerebellum part {neocerebellum} {pontocerebellum} is anterior and posterior cerebellar lobes, for skilled or complex movements and intentions. Neocerebellum receives from pons and sends through superior peduncle.
Excitatory axons {parallel fiber} from cerebellum send to Purkinje cell dendrites. Perhaps, parallel fibers provide input vectors. Parallel fibers form sequential-activity lines, with one synapse per Purkinje cell. Parallel fibers can induce long-term depression.
Cerebellum has seven million large neurons {Purkinje cell}, which receive 200,000 synapses on planar dendritic spines and send inhibitory GABA output to cerebellar deep nuclei.
A forebrain region {cerebrum}| {cerebral hemispheres} {cerebral cortex} above midbrain includes telencephalon and diencephalon. Cerebrum initiates behavior, causes consciousness, stores memories, and controls internal stimuli.
size
Human cerebral cortex is 2000 square centimeters in area and 300 cubic centimeters in volume.
neurons
Cerebral cortex has more than one billion neurons. Half are pyramidal cells. Surface folding increases area and density. Cerebrum has 100,000 to 300,000 neurons per cubic millimeter.
parts
Mammal cerebrum includes neocortex and hippocampus.
layers
Mammal cerebral-cortex layers average 2 millimeters thick, differing in thickness among the 52 Brodmann areas. Layers are on outside, with axon fibers on inside. Macrocolumns and their minicolumns go through all layers.
Limbic system typically has three-layered allocortex. Cingulate gyrus and insula have three to six cortex layers in juxtallocortex. Human cerebral hemispheres have six-layered neocortex. Top three layers are only in genus Homo and act as a unit. Cortex has only one inhibitory-cell layer.
layers: general
Layer 1 has horizontal cells. Layer 2 has small, round, granular cells. Layer 3 has pyramidal cells. Layer 4 has closely packed granular cells. Layer 5 has large and numerous pyramidal cells and has large spindle neurons, which begin after birth in anterior cingulate and frontal area FI and are for attention and self-reflection. Layer 6 has spindle-like small cells.
layers: detail
Top layer 1 contains pyramidal cell apical dendrites from other layers in macrocolumn and axons from other cortical areas, with few neuron cell bodies. Layers 2 and 3 have superficial pyramidal cells. Layers 1, 2, and 3 {superficial layers} receive from their column, other cortex, and thalamus matrix neurons. Layer 4 has many excitatory spiny stellate cells but few pyramidal neurons. Layer 4 has sublayers IVa, IVb, IVc, and IVc in visual cortex. Layers 5 and 6 {deep layers} have pyramidal cells, some with dendrites to layer 1, that send to cortex, thalamus, superior colliculus, and spinal cord.
layers: input and output
Layers 1 and 2 and layer-3 upper part receive from other cortical-area layer 4. Layers 1 and 2 and layer-3 upper part send to other cortical-area layer 5. Layer-3 lower part receives from outside cortex and sends to layers 1 and 2 and layer-3 upper part. Layers 2 and 3 mostly connect to layers 2 and 3, either laterally or through U-shaped fibers going down into white matter and then back up. Layers 2 and 3 also send to layer-3 lower part and to layer 4 for feedforward responses. Some layer-2-and-3 superficial neurons send output to layers 5 and 6. Layer 4 receives from layer 6 and from outside cortex. Layer 4 sends mainly to layers 1 and 2 and layer-3 upper part. Layer 5 receives from layers 1 and 2 and layer-3 upper part, from whole cortex. Layer 5 sends to layer 6, spinal cord, brainstem, basal ganglia, and hypothalamus. Layer 5 neurons do not project to other cortical areas, thalamus, or claustrum. Layer 6 receives from layer 5. Some layer-6 neurons receive from layer 4C. Layer 6 sends short vertical axons back to layer 4 and outputs to thalamus. Some layer-6 neurons send to thalamus, lateral geniculate nucleus, and claustrum.
layers: connections
Lateral axons are within all layers. Ascending and descending fibers connect all layers. Adjacent cerebral cortex areas always connect to each other. Distant cortical regions connect reciprocally.
input
Cerebrum receives from higher brainstem and limbic system. Brainstem or limbic system damage reduces cerebrum activity, and people enter dreamy state.
Ascending fibers to cerebral cortex have slow, long lasting NMDA receptors.
Excitatory input comes from ipsilateral cerebral cortex, and inhibitory input comes from contralateral cortex. Cerebral cortex mainly inhibits lower brain. It does not control older brain parts but interacts with them.
Cortical motor areas receive input from association areas, corticospinal tract, thalamus, post-central gyrus somaesthetic area, and frontal lobe motor areas.
input: topography
Cortical neurons separated by less than several hundred microns receive similar input and send similar output.
input: multisensory
Cortical neurons for multisensory information lie next to cortical areas for one sense. Superior-temporal, intraparietal, frontal, and prefrontal lobes are for multisensory convergence [Bruce et al., 1986].
input: synapses
70% of excitatory synapses on cerebral-cortex superficial pyramidal neurons are from less than 0.3 millimeters away. Few come from outside cerebral cortex. Average cortical-neuron effect on other neurons is 0.050 to 5 millivolts. Probability of one synapse causing a spike is 0.1 to 0.5.
Cortical neurons have dendritic trees with diameter 0.3 millimeters. Most neurons receive 100 synapses from 100 neurons and send to 100 other neurons. 8000 neurons eventually affect cortical neurons.
input: processing
Training, learning, and willing have widespread cortical activity and take one second.
Consciousness involves coordinated synchronized impulses in cerebral cortical neurons for over 100 milliseconds. Perhaps, impulses are high-frequency bursts, rate codes, oscillations at 40 Hz, or other synchronized impulses. Visual consciousness involves cortical layers 5 and 6. Cortical layer 4 receives input. Cortical layers 2 and 3 are for unconscious processing.
output
Motor and sense cortex sends axons to cerebellum, basal ganglia, and hippocampus, which send axons to thalamus and cortex, with no reciprocity.
Cerebral-cortex descending fibers can cause lower-brain-neuron long lasting subthreshold depolarization.
Cerebrum primary sense areas send to nearby secondary areas and nowhere else. Secondary sense areas send to other-hemisphere corresponding area, other same-hemisphere secondary areas, and cerebral association areas. Association areas interconnect.
output: synchronization
Cerebral-cortex superficial-pyramidal-cell axons travel horizontally in same cortical layer 0.4 to 0.9 millimeters and then make terminal clusters on other superficial pyramidal cells. The skipping pattern aids neuron-activity synchronization.
output: divergence
As signal travels farther into cerebrum, neuron receptive-field sizes increase and features to which neurons respond become more complex, because later areas receive input from several earlier areas.
output: feedback
Later areas send signals back to earlier areas.
damage
People with no cerebrum can sleep, awake, smile, and cry. They feel no danger or hunger and have no spontaneous behavior.
Damage to cortex causes poor memory retrieval and poor habit inhibition. Cortex loss does not affect general consciousness.
Limbic system cortex {allocortex} {archicortex} typically has three layers.
Cortical regions {association cortex} can record pattern and feature shapes, sizes, types, strengths, and indexes. Association cortex uses serial and parallel detectors at sensory field points to find perceptual features and associate them with similar patterns.
vector field
Associative cortex receives spatial and temporal chemical and electrical signal-intensity patterns from neuron arrays and then distributes spatial and temporal chemical and electrical signal patterns to neuron arrays, including self. Spatial and temporal pattern is like wave front or vector field. Association cortex transforms, and so maps, input field to output field. Mapping uses tensors. Vector-field output vectors are input-vector functions. Vector fields have gradients, flows, constancies, covariances, and contravariances. For example, before intention to move and before movement begins, non-motor cortex has activity. Brain compensates for body movements that change sensor and muscle positions.
levels
Primary associative cortex tracks interactions, combinations, correlations, constancies, covariances, and contravariances among neural signals.
Secondary associative cortex creates absolute time and space, through body-position and surrounding comparisons, as body, head, and eyes move. Spaces have one, two, two and a half, or three dimensions for different uses. Model locates sense organs and muscles in three-dimensional time and space, as objects where events happen. Three-dimensional space-time does not depend on body and has vertical, front, right, and left. Absolute space-time allows perspective changes and unites perception and action.
Tertiary associative cortex is only in human brain and coordinates intermodal sense information.
Rodent somatosensory-cortex regions {barrel field} can be for sensations from same-side whiskers (Thomas Woolsey and Hendrik van der Loos) [1975]. Neuron groups {barrel, neuron} can respond first for one whisker, respond later for nearby whiskers, and respond even later for farther whiskers. Barrels feed back to previous barrels. Thalamus also has barrel-like regions {barreloid}. Brain stem has barrel-like regions {barrelet}.
Passive signal reception has refractory periods, but active exploration has no refractory periods. Active exploration has priming.
Brain hemispheres have 52 regions {Brodmann area}, classified by cortical-layer thickness. Average human Brodmann area is two square inches. Brodmann areas can have one to six distinct physiological subregions, each one-centimeter square. For example, area 17 has one map.
A cleft {central fissure} {central sulcus} {rolandic sulcus} lies between pre-central gyrus and post-central gyrus.
Humans perform some mental functions predominantly in left or right cerebrum {cerebral dominance}.
Cortex folds on itself {convolution, cortex}| in set patterns.
From corpus callosum to gray matter {cingulum} are myelinated axons.
In placental mammals, 800 million axons {corpus callosum}| connect left and right cerebral hemispheres [Aboitiz et al., 1992] [Kretchmann and Weinrich, 1992].
Brain also has smaller connections between hemispheres.
processing
Corpus-callosum posterior splenium relays visual information from left visual field to speech area.
damage
Cutting corpus callosum causes epileptic-like brain firing.
split brain
Cutting all connections between left and right hemispheres can show psychological functions performed by hemispheres. Cutting only corpus callosum makes no change, because other connections can still carry signals.
After cutting, people cannot match unseen object felt by the hand to seen object felt by right hand. Two separate experiences or discriminations can happen simultaneously.
Both hemispheres know words, pictures, and metaphorical relationships. Both hemispheres are aware.
Will, consciousness, motivation, and coordination are only slightly depressed, except for short concentration lapses. Perception, object location, and space orientation stay the same.
Either hemisphere can activate, depending on task, sex, age, handedness, education, and training.
Over time, functions performed by hemispheres become more alike.
brainstem
Brainstem dismay, embarrassment, or amusement feelings, generated in one hemisphere by threat, risk, or teasing perceptions, can cause body movements, emotions, attention, and orientation.
Mammal neocortex cerebral hemispheres {isocortex} can have six layers.
Cingulate gyrus and insula {juxtallocortex} have three to six cortex layers.
A brain hemisphere {left hemisphere}| stores categorical relationships and organizes movements in right limbs.
functions
It has region, between occipital, parietal, and temporal lobes, for mathematical thinking. It is better at propositional speech. It predicts how words will sound. It stores learned skills. It directs right-hemisphere left-limb control. It has relatively more neurons and fewer axons, so connections are shorter for analyzing details.
damage
Damage to left posterior hemisphere harms language coding. Large damage to left hemisphere causes language ability loss but does not affect automatic language.
Cortex can not fold and is smooth {smooth brain} {lissencephaly}.
Cortex {neocortex}| {new forebrain} can be only in mammals, for sense memory [Abeles, 1991] [Allman, 1998] [Braitenberg and Schüz, 1991] [Braitenberg, 1984] [Felleman and Van Essen, 1991] [Mountcastle, 1957] [Mountcastle, 1998] [Passingham, 1993] [Peters and Rockland, 1994] [Peters et al., 1991] [Rockel et al., 1980] [White, 1989] [Zeki, 1993]. It has uniform neuron structure.
regions
In humans, neocortex has at least 52 distinct cellular areas. Cat neocortex has 36. Rat neocortex has 13. In some primates, striate cortex differs from motor cortex, with giant Betz cells, in laminar organization, cell number, cell types, and general connectivity patterns.
Upper-temporal-lobe region {planum temporale} controls complex movements and language processing.
Nuclei {precuneus} can be about autobiographical memory.
Sense neurons have spatial regions {receptive field} from which stimuli can come [Kuffler, 1952] [Ratliff and Hartline, 1959]. Retinal neurons have receptive fields with center circle and surrounding annulus with opposite polarities {center-surround organization}.
Vision has topographic maps {retinotopic map}, in which fovea has more points than surround.
Hemispheres {right hemisphere}| can have relatively fewer neurons and more axons, so connections are longer. It can recognize larger patterns. It has region, between occipital, parietal, and temporal lobes, for spatial thinking. It analyzes visual and spatial relations. It gives direction sense. It can perceive shapes by touch. It recognizes faces. It understands interpersonal acts. It does more distance judging. It judges temporal order such as simultaneity and time differences. It synthesizes whole situation to develop emotional response.
language
Right hemisphere cannot express speech but can comprehend spoken and written language. It can judge word meaning from sound but cannot make sound from visual image. It comprehends all grammatical word classes, except difficult, abstract, or rare words. It cannot comprehend proposition. It cannot group using tokens. It is better at automatic speech and skilled motor acts. It can solve simple arithmetic problems.
music
Right hemisphere is for intonation, background noise elimination, music, and chords.
Ventrobasal thalamus and ventral tegmentum dopaminergic neurons stimulate cerebrum {sensorimotor cerebral cortex}.
Cerebral hemisphere posterior parts {sensory cortex} receive, preserve, and elaborate information from external world. Three million sense-neuron axons go to cerebral cortex.
Cortex regions {somaesthetic cortex} can be for touch, have double body-surface representation, depending on number of surface skin receptors, and discriminate among touch sensations.
Cortex regions {somatosensory cortex} can receive touch information from thalamic-relay nucleus on somatosensory area 1 {area S1}, which sends to somatosensory area 2 {area S2}. Attention affects somatosensory cortex [Steinmetz et al., 2000].
Brain has touch topographic map {somatotopic map} {somatosensory map} behind central fissure. Largest areas are for body regions used most frequently for tactile orientation and analysis, such as face, forepaw, and forelimb. Somatotopical and visual body-surface representation is upside down in vertebrate brains. Somatosensory-map hand region changes size, if hand exercises more. Body-movement topographic map in front of central fissure aligns with somatosensory map.
A cleft {lateral fissure} {sylvian fissure}| is between temporal lobe and parietal lobe.
Brain color-processing regions {TPO region} {temporal parietal occipital region} can be at temporal-lobe, parietal-lobe, and occipital-lobe junction near angular gyrus. It also represents sequences and order. It connects touch, hearing, and vision. Perhaps, left side is multisensory, and right is spatial [Ramachandran, 2004]. TPO region expanded greatly from mammals to humans. Perhaps, it is for moving in trees as hands grasp branches.
Brain has two-dimensional neuron arrays {topographical mapping} {topographic map, brain}| for analysis [DeYoe et al., 1996] [Dow, 2002] [Hübener et al., 1997] [Horton and Hoyt, 1991] [Swindale, 2000] [Tootell et al., 1998] [Van Essen et al., 2001].
locations
Vision has topographic maps in retina, lateral geniculate nuclei, area V1, and area V2, for analyzing color, movement, disparity, orientation, size, and spatial periodicity. Audition has at least six topographic maps in primary auditory cortex and surrounding cortex, for analyzing tones and locations. Touch has at least four topographic maps in somatosensory cortex and surrounding cortex, for analyzing surface texture and shape. Proprioception has at least four topographic maps, for analyzing muscle stretching, compressing, and twisting.
Motor control also uses at least four topographical maps.
Sense and motor maps align and connect. Brain maps in different brain areas are not homogeneous and not isotropic.
layers
Maps can have neuron layers.
processing
Neurons that process signals from neighboring positions or times are near each other.
processing: number
Neuron number is proportional to processing amount. In touch maps, hand has more neurons and larger area than back. In retinotopic maps, fovea has more neurons and larger area than whole surround.
processing: inhibition
Connections within map are mostly inhibitory. Lateral inhibition enhances contrast and suppresses noise.
Topographic maps with diffuse connections and large receptive fields are beside maps with specific connections and small receptive fields, so map sets work at different spatial and temporal scales.
processing: filling-in
Maps can extrapolate and interpolate.
processing: space
Coordination among two-dimensional topological maps allows two-and-a-half-dimensional and three-dimensional representations.
In visual cortex, columns {hypercolumn} of 100 cells, one millimeter diameter, can detect stimuli from one spot in visual field, from both eyes. Hypercolumn can detect orientation, from 0 to 180 degrees, and depth, and so perspective, size, shape, and surfaces. Hypercolumn macrocolumns can receive from left or right eye. Hypercolumn cells use several visual-field region sizes. Cells can be simple, complex, and hypercomplex.
Neuron columns {macrocolumn} can share functional properties for one body-surface patch [Buxhoeveden and Casanova, 2002] [Koulakov and Chklovskii, 2001] [Mountcastle, 1957] [Mountcastle, 1998] [Rakic, 1995].
properties
Macrocolumn is 0.4 to 1.0 millimeters diameter. It goes through all six cortical layers. It has 100 minicolumns. It is plastic.
bands
It makes interdigitating curved planes. Somatosensory neurons responsive to skin stimulation alternate with neurons for joint and muscle receptors, every 0.5 millimeters. New-World monkeys do not have ocular dominance columns.
cause
Perhaps, self-organizing competition and cooperation, during development and learning, cause macrocolumns.
Macrocolumn units {minicolumn} are in all reptile, bird, and mammal cortex. Column is 23 micrometers to 65 micrometers diameter, thin hair size. It contains 110 to 250 neurons. It organizes around bundle of 12 apical dendrites. It goes through all six cortical layers. It is 30 micrometers apart in human cortex.
processing
Within ocular-dominance macrocolumns, minicolumn orientation columns can prefer lines and edges that tilt same angle from vertical {orientation tuning, minicolumn}. Superficial-layer recurrent excitation coordinates distant minicolumns.
growth
Cortex grows by adding minicolumns, which travel from inside to outside. Perhaps, self-organizing competition and cooperation, during development and learning, cause minicolumns.
Minicolumns {ocular dominance column} can have 3000 input axons and 50,000 output axons. Signals to column from right or left eye ocular dominance process faster. Visual-cortex hypercolumns have equal numbers of both ocular dominance columns [Hubel and Wiesel, 1968] [Hubel, 1988] [Horton and Hedley-Whyte, 1984] [LeVay et al., 1985].
Ocular dominance columns are independent units 0.4 to 0.5 millimeters apart. They have bands for same orientation or same eye.
Ocular dominance columns are only in Old-World monkeys, apes, and humans, and not in New World monkeys.
Minicolumns {orientation column} can have 3000 input axons and 50,000 output axons [Blasdel and Lund, 1983] [Blasdel, 1992] [Das and Gilbert, 1997] [LeVay and Nelson, 1991]. Orientation column is an independent unit. It has 120 cells, all for one orientation. Columns are 0.4 to 0.5 millimeters apart.
bands
Columns have bands for same orientation or same eye.
functions
Cells can detect stationary objects at locations. Cells for larger areas can check for movement and flashing, often from one direction only. Cells can check for corners, lengths, and trajectories. Orientation columns can extract contours, as curve envelopes, or can output cell-signal mean values, most-active-neuron signals, or pulse patterns.
Diencephalon nerve-fiber band {fornix} connects amygdala and hippocampus to septum, preoptic area, and hypothalamus.
Nuclei {epithalamic nuclei} near thalamus include habenular nuclei, pineal gland, and habenular commissure.
Fibers {habenular commissure} connect habenular nuclei in epithalamus.
Epithalamic nuclei {habenular nuclei} can receive from thalamus.
Foremost ventral brainstem {hypothalamus, brain}| connects to limbic system within temporal lobe.
input
Hypothalamus receives excitation and inhibition from non-sense and non-motor cortex that organizes emotions and behavior.
output
Hypothalamus has dopaminergic nuclei, cholinergic nuclei, and histaminergic nuclei that project in net over whole brain.
Hypothalamus makes orexin, which goes to lateral-hypothalamus receptors.
hormones
Hypothalamus parvocellular neurons respond to adrenal glucocorticoid hormones to decrease corticotrophin-releasing-factor production.
Hypothalamus sends to gland regulators to control hormone production and sends to sympathetic and parasympathetic nervous systems.
nuclei
Hypothalamic nuclei include arcuate, dorsomedial, mamillary, paraventricular, optic chiasm, preoptic, posterior, suprachiasmic, supraoptic, tuber cinereum, and ventromedial nuclei. Sensory hypothalamus has mamillary bodies. Ergotropic centers are in hypothalamus posterior. Trophotropic centers are in hypothalamus rostral part, septum, and preoptic region.
functions
Hypothalamus is for aggression, submission, fighting, flight, rage, attention, aversion, and fear.
It is for sex behavior and sex inhibition, using sex hormone receptors. It organizes copulation in front hypothalamus and septal area.
It is for appetite, eating, digestion, micturition, and defecation. It organizes body metabolism, heat production, body temperature, and circulation.
Hypothalamus is for repose, sleep, and wakefulness. Sensory hypothalamus carries wakefulness impulses from reticular formation to thalamus.
Hypothalamus does not initiate behavior.
evolution
At first-ventricle bottom, chordates had secretory cells that evolved to make hypothalamus.
Hypothalamus regions {arcuate nucleus} can have main proopiomelanocortin (POMC) neurons and send to limbic system and brainstem. POMC is precursor of MSH.
processing
Arcuate nucleus has region for appetite and region for satiation. Ghrelin gut peptide stimulates appetite region. PYY gut peptide inhibits appetite region. Leptin hormone stimulates satiation region and inhibits appetite region. Insulin hormone stimulates satiation region and inhibits appetite region. Satiety region sends alpha-MSH to MC4 second-satiation-region receptors. Appetite region sends AgRP to second satiety region, neuropeptide Y (NPY) to second appetite region, and melanin concentrating hormone (MCH) peptide.
hypothalamus region {dentate gyrus}.
Hypothalamic ganglia {dorsomedial hypothalamic nucleus} can be for ejaculation.
Hypothalamic nuclei {lateral hypothalamic nucleus} can be for hunger.
Hypothalamus nuclei {mamillary bodies} can be for long-term memory.
Hypothalamus regions {motor hypothalamus} can be main below-cortex limbic-system part, control reflex pupil dilation, and integrate autonomic nervous system, together with old cortex. Fore part is for parasympathetic nerves. Back part is for sympathetic nerves. It has richest blood supply, reciprocally connects blood vessels to pituitary gland, and regulates pituitary-hormone secretions.
functions
It affects homeostasis, regulates body temperature, regulates water metabolism and excretion, and regulates food intake. It makes overall sexual behavior pattern and has pleasure center related to sex behavior.
Hypothalamic nucleus {paraventricular nucleus} receives from amygdala and sends to posterior pituitary.
Tuberal region has nucleus {posterior hypothalamic nucleus}, beside arcuate nucleus, that connects with lateral mamillary nucleus.
Hypothalamic nuclei {preoptic nucleus} can have trophotropic centers. Medial preoptic area is about maternal behavior.
Light on retina signals optic-nerve retinohypothalamic tract, which signals hypothalamus nuclei {suprachiasmic nucleus} {suprachiasmatic nucleus} (SCN), which causes daytime pineal-gland melatonin-production reduction by inhibiting paraventricular nuclei.
Hypothalamic nuclei {supraoptic nuclei} can project to posterior pituitary.
hypothalamic nucleus {tuber cinereum}.
Hypothalamic nuclei {ventromedial hypothalamic nucleus} can be for satiation.
Above hypothalamus is golf-ball-sized ellipsoidal region {thalamus}|.
functions
Thalamus is for attention, respiration, short-term memory, and long-term memory. It can detect sensations, temperature, pain, and moderate skin stimulation. It identifies objects and initiates avoidance behavior. In mammals and humans, it directs attention to language. It affects autonomic system.
Thalamus has feeding center that controls eating behavior. It has satiety center that has glucose receptors.
anatomy
Ventral reticular nucleus is thin shell that surrounds walnut-sized dorsal thalamus. Thalamus has few intrinsic neurons.
anatomy: nuclei
Thalamic nuclei include anterior, centromedian, dorsolateral, dorsomedial, intralaminar, lateral geniculate for vision, medial geniculate for audition, multimodal, pulvinar, reticular, ventral anterior, ventral lateral, ventral posterior, and ventrobasal complex for somatosensation [Jones and Peters, 1986] [Jones, 1985] [Sherman and Guillery, 2001].
input
Main inputs to cortex first pass through two dozen thalamus regions. Glomeruli and glia surround incoming sense-nerve axons. Thalamus has projection areas for skin regions, with subareas for touch, pressure, muscle, and joint movement. Thalamus has input neurons for taste and for taste and touch.
Number of cortical fibers projecting back to thalamic nuclei is much larger than number of fibers from senses to thalamus.
output
All nuclei have matrix cells with diffuse projections. Thalamus has as many outputs as inputs but has no axon collaterals.
Thalamus inhibits optic tectum in lower vertebrates.
Core relay neurons send to cortex layer 4. Matrix neurons send to cortex layers 1, 2, and 3. Clustered neurons {core neuron}, such as magnocellular and parvocellular neurons, excite layer 4 in small cortex regions. Other neurons, such as koniocellular neurons, send to layers 2 and 3 in larger cortical regions {matrix neuron} [Jones, 2002].
damage
Non-specific thalamus damage causes consciousness loss. Thalamic damage can cause sense or motor loss.
processing
Input causes one spike and then 100 milliseconds of inhibition. Thalamic neurons can replicate sense input or can burst in 30-Hz to 40-Hz pattern unrelated to input. Thalamus reticular nucleus can switch lateral geniculate nucleus into burst mode.
Limbic-system anterior-thalamus region {anterior thalamic nucleus} {anterior sensory thalamus} relays affective visceral information to cortex and controls ergotropic behavior through sympathetic nervous system.
Thalamic nucleus {centromedian nucleus} {centrum medianum nucleus} sends to cerebellum and corpus striatum.
Thalamic ganglia {dorsolateral thalamic nucleus} can send to parietal lobe.
A limbic-system part {dorsomedial thalamic nucleus} can receive from olfactory lobe and amygdala and send to frontal lobe and hypothalamus.
Lateral geniculate nucleus sends, through optic radiation {geniculostriate pathway, brain}, to occipital lobe visual cortex area V1. Geniculostriate and tectopulvinar pathways interact. Lateral geniculate nucleus damage causes poor acuity.
Thalamus medullary-laminae nuclei {intralaminar nuclei} {intralaminar complex} (ILN) {nucleus circularis} can have neurons organized in torus and include geniculate bodies. ILN surrounds medial dorsal nucleus. Other thalamic nuclei are principal nuclei.
purpose
Loops through striatum, pallidum, and thalamus underlie arousal and awareness.
input
Intralaminar nuclei receive from reticular formation for arousal, spinothalamic system for temperature and pain, trigeminal complex for temperature and pain, cerebellum dentate nuclei for proprioception, globus pallidus for motor feedback, periaqueductal gray for emotion, substantia nigra for emotion, amygdala for emotion, and vestibular nuclei for body position.
Laterodorsal tegmentum, peduncle, and pons cholinergic neurons excite excitatory thalamocortical-relay-neuron nicotinic receptors, and those cholinergic neurons inhibit inhibitory thalamic-reticular neuron muscarinic receptors, resulting in new excitation. Basal forebrain cholinergic and noradrenergic axons go to Layer I and to lower layers. Ventrobasal nucleus sends to Layer IV.
output
Intralaminar nuclei connect, with collaterals to nucleus reticularis, to striatum, pulvinar, all cortical layers 1 to 3, except visual cortex and inferotemporal cortex, and basal ganglia.
Intralaminar nucleus {centrum medianum} {entromedian nucleus} stains differently, is for will, and sends to motor cortex and striatum.
Intralaminar-nuclei matrix neurons can send to Layer I, to modulate lower layers. Intralaminar-nuclei core neurons can send mainly to Layer V and VI, to carry main signals.
damage
Strokes in thalamoperforating arteries {paramedian arteries} can damage both ILN. Both-side damage ends waking consciousness [Baars, 1995] [Bogen, 1995] [Cotterill, 1998] [Hunter and Jasper, 1949] [Kinney et al., 1994] [Koch, 1995] [Llinás and Paré, 1991] [Minamimoto and Kimura, 2002] [Newman, 1997] [Purpura and Schiff, 1997] [Schlag and Schlag-Rey, 1984].
Lateral geniculate nucleus has six separate cell layers, four parvocellular layers at top with small cells and two magnocellular layers at bottom with large cells. Between layers are cone-shaped cells {koniocellular neuron} that code for blue-yellow opponency, the difference between S cones and L+M cones [Calkins, 2000] [Chatterjee and Callaway, 2002] [Dacey, 1996] [Nathans, 1999].
Thin thalamic nuclei {lateral dorsal nucleus} can be in anterior, be for memory and emotion, and send to anterior cingulate gyrus.
Thalamus nucleus {lateral geniculate nucleus}| (LGN) is for object identification [Przybyszewski et al., 2000] [Shepherd, 1998] [Sherman and Guillery, 2001] [Sherman and Koch, 1998].
input
LGN receives from all senses except olfaction, especially from retinal ganglion neurons. It is sensitive to eye position. It has dermatomal segments to represent body sensations.
Thalamus receives much more feedback from cortex than it sends to cortex. Such positive and negative feedback probably applies learned and innate information to bias stimulation, which predicts stimuli [Koch, 1987] [Mumford, 1991] [Mumford, 1994] [Rao and Ballard, 1999].
LGN has circular receptive fields.
output
LGN sends, through optic radiation {geniculostriate pathway, vision}, to visual cortex area V1 in occipital lobe. Geniculostriate and tectopulvinar pathways interact.
LGN sends to somaesthetic cortex.
LGN sends to overlapping, multiple lateral geniculate nucleus cells {relay cell}. Through dendrodendritic connections, LGN affects neurons up to five millimeters away.
Neurons inhibit themselves.
damage
Damage to lateral geniculate causes poor acuity.
anatomy: layers
Lateral geniculate nucleus has six separate cell layers, four parvocellular layers at top with small cells and two magnocellular layers at bottom with large cells. Parvocellular and magnocellular core neurons send to one cortex region.
LGN layers 1, 4, and 6 are for opposite-side eye. Layers 2, 3, and 5 are for same-side eye. Layer 1 and 2 neurons respond to OFF, at any wavelength. Layer 3 and 4 neurons respond to ON or OFF, at wavelength range. Layer 5 and 6 neurons respond to ON, at wavelength range. Layer 3 and 4 neurons have opponent cells for red-green and blue-yellow.
anatomy: magnocellular
Magnocellular cells receive from bipolar cells with bigger dendrite trees and send transient signals to visual-cortex layer 4c-alpha and layer 6. These large cells are for temporal resolution, movement, and flicker. Optic-tract axons from right and left eyes synapse on separate magnocellular neurons, in bands.
anatomy: parvocellular
Parvocellular cells receive from midget cells and send sustained signals to visual-cortex layer 4cbeta. Small cells are for color, spatial resolution, texture, shape, depth perception, and stereopsis [Merigan and Maunsell, 1993] [Schiller and Logothetis, 1990].
anatomy: koniocellular
Between layers are koniocellular neurons {matrix cell} that code for blue-yellow opponency, the difference between S cones and L+M cones [Calkins, 2000] [Chatterjee and Callaway, 2002] [Dacey, 1996] [Nathans, 1999]. Koniocellular cells go to several regions.
anatomy: Y cells
Y cells maintain activity after moving object crosses receptive field, using cortico-thalamic feedback.
color processing
Brain has four opponent processes. Cell can react oppositely to red and green or green and red. Cell can react oppositely to blue and yellow or yellow and blue. Luminance is sum of red and green. Comparisons cross, so the three colors add orthogonally.
Magnocellular cells {magnocellular layer} receive from bipolar cells with bigger dendrite trees and send transient signals to visual-cortex layer 4c-alpha and layer 6. These large cells are for temporal resolution, movement, and flicker. Optic-tract axons from right and left eyes synapse on separate magnocellular neurons, in bands.
Fibers {massa intermedia} link left and right thalamus.
Peanut-sized thalamus nuclei {medial dorsal nucleus} can be for emotions and receive from and send to amygdala and prefrontal cortex, mostly orbitofrontal cortex. Intralaminar nuclei surround it.
Thalamus nuclei {medial geniculate nucleus} can be for sound; receive from cochlea, lateral lemniscus, and inferior colliculus; and send to temporal lobe.
Lateral thalamic nuclei {medial lateral thalamic nucleus} can be for memory.
Thalamic regions {medial lemniscus} can mix input from touch receptors, thermoreceptors, and nociceptors along spinothalamic tract. Descending inhibition enhances contrast between stimulated area and adjacent regions or admits only certain input to higher levels, and so affects attention.
Parvocellular cells receive from bipolar cells with small dendrite trees {midget cell} and send sustained signals to visual-cortex layer 4cbeta. Small cells are for color, spatial resolution, texture, shape, depth perception, and stereopsis [Merigan and Maunsell, 1993] [Schiller and Logothetis, 1990].
Thalamus regions {motor thalamus} can connect to basal ganglia, cerebellum, motor neocortex, vagus nerve, and hypothalamus and is in visceral and autonomic system.
Parvocellular cells {parvocellular layer} receive from midget bipolar cells with small dendrite trees and send sustained signals to visual-cortex layer 4cbeta. Small cells are for color, spatial resolution, texture, shape, depth perception, and stereopsis [Merigan and Maunsell, 1993] [Schiller and Logothetis, 1990].
Thalamus nuclei {pulvinar nucleus} can have inferior, lateral, and medial nuclei that are for attention, are multisensory, and receive from superior colliculus and retinal ganglion cells [Desimone et al., 1990] [Grieve et al., 2000] [Kinomura et al., 1996] [LaBerge and Buchsbaum, 1990] [LaBerge, 2000] [Rafal and Posner, 1987] [Robinson and Cowie, 1997] [Robinson and Petersen, 1992]. Pulvinar nucleus excites posterior parietal and inferior temporal lobes for external stimuli. Nucleus sides {lateral pulvinar nucleus} inhibit cerebral cortex to suppress irrelevant events, increase resolution, minimize receptive fields, and specify attention focus.
Thin cell sheet {reticular nucleus} {nucleus reticularis thalami} (nRt) surrounds thalamus and has only inhibitory GABA neurons. Reticular nucleus receives from most axons to and from neocortex and interacts with its own neurons. It sends output to thalamus, to organize sleep rhythms, such as deep-sleep spindling and delta waves, and select sense channels to cortex.
thalamus nucleus {semilunaris nucleus}.
Thalamus regions {sensory thalamus} can have reverberatory circuit from reticular formation and hypothalamus to cortex. It carries wakefulness impulses. It mediates contact, temperature, and pain consciousness. It has anterior, lateral geniculate, medial-lateral, pulvinar, semilunaris, and ventral centrum medianum nuclei.
Motor nucleus {ventral anterior thalamic nucleus} receives from cerebellum and globus pallidus and sends to corpus striatum.
thalamus nucleus {ventral centrum medianum nucleus}.
Motor nucleus {ventral lateral thalamic nucleus} receives from cerebellum and globus pallidus and sends to cerebral motor cortex.
Thalamic region {ventral medial basal thalamus} receives from parabrachial nucleus and nucleus tractus solitarius and sends to posterior insula.
Thalamic region {ventral medial posterior thalamus} receives from trigeminal nucleus and sends to posterior insula.
Thalamic region {ventral posterior thalamic nuclei} includes sensory ventral posterolateral nucleus and ventral posteromedial nucleus. It receives from medial lemniscus, spinothalamic tract, and trigeminal nerve and sends to postcentral gyrus.
Thalamus nucleus {ventrobasal complex} receives from dorsal column nuclei and sends to primary somatosensory cortex.
Cerebrum has frontal region {frontal lobe}| [Barcelo et al., 2000] [Brickner, 1936] [Churchland, 2002] [Colvin et al., 2001] [Damasio and Anderson, 2003] [Dennett, 1969] [Eliasmith, 2000] [Fuster, 2000] [Nakamura and Mishkin, 1980] [Nakamura and Mishkin, 1986].
purposes
Frontal lobe stores systematic semantic concepts and relationships. It analyzes and stores somatosensory, visual, and auditory information. It anticipates motor and cognitive effects. It is about attention, arousal, anxiety, and mood. It affects spatial, recognition, and short-term memory.
purposes: behavior
Frontal lobe establishes action plans and maintains motivations. It controls movement schedule and sequence. It regulates motor, emotional, sexual, and appetitive behaviors. It controls bipedal posture and habituation. It determines energy level and interests. When preparing for motion, frontal-cortex neurons have high-frequency oscillations.
damage
Frontal-lobe damage can impair voluntary movements and delayed responses. Damage can cause hyperactivity, after one day. Damage can eliminate chronic pain responses. Damage can cause no-emotion states. Damage can prevent solving problems that have multiple answers or that require multiple object views. Damage can cause repeated behavior {perseveration, frontal lobe}, as shown by Wisconsin card-sorting test. Damage can cause impaired associational learning. Damage can reduce introspection and daydreaming. Damage can prevent goals. Damage can cause people not to know that they are deficient.
anatomy
Frontal lobe connects to nucleus accumbens, locus coeruleus, hypothalamus, limbic system, precentral cortex, striatum, and posterior parietal, prestriate, and temporal lobes.
attention
Attention affects frontal lobe [Huerta et al., 1986] [Schall, 1997].
Frontal-cortex midline gyrus {anterior cingulate gyrus} {anterior cingulate cortex} (ACC) is for attention, consciousness, voluntary control, and pain. It measures pain unpleasantness. It has Brodmann areas 24, 25, 32, and 33. Multisensory cells resolve conflicts between signals, such as Stroop effect.
Left-frontal-lobe inferior regions {Broca's area} {Broca area}, above lateral sylvian fissure, in front of motor cortex, control speech muscles that make grammatical language [Di Virgilio and Clarke, 1997].
Broca's area and Wernicke's area connect {arcuate fasciculus}.
Broca's area seems to have existed in Homo habilis.
Frontal-lobe midline region {cingulate gyrus}| surrounds corpus callosum.
Frontal-lobe areas {entorhinal area} {entorhinal cortex} can connect to hippocampus, dentate gyrus, sensory frontal lobe, temporal lobe, cingulate neocortex, and olfactory cortex. Entorhinal cortex receives from olfactory bulb. Entorhinal cortex sends sense input to hippocampus.
damage
Entorhinal cortex loss causes inability to consciously remember facts or events, such as new category members or unique examples. Damage does not affect perceptual-motor skills with no conscious internal representations, such as mastering task over several sessions or retrieving previously acquired factual knowledge.
evolution
Entorhinal cortex developed early in evolution.
Frontal-lobe interior orbital surface posterior part {insula, brain}| {insular cortex} includes amygdala and hippocampus. Posterior insula receives from ventral medial posterior thalamus and ventral medial basal thalamus and sends to anterior insula, which sends to anterior cingulate and ventromedial frontal lobes. Insula controls trophotropic behavior through parasympathetic nervous system. Anterior insula responds to pictures of self. Insula receives from taste neurons. Insula helps recognize consonants.
Left lateral frontal lobe {left lateral frontal lobe} stores word meanings, together with Wernicke's area [Churchland, 2002] [Dennett, 1969] [Eliasmith, 2000]. Damage blocks understanding of verb classes but not noun classes.
Damage to fusiform and lingual gyri {lingual gyri} causes no color perception.
Frontal-lobe neuron system {mirror-neuron system} {mirror neuron}, in rostral ventral premotor area F5, allows perception, understanding, and action imitation. Neurons are active when people perform actions and when other people perform same actions. Brain connects voluntary-muscle commands, proprioception, visual perception, and sounds.
theories
Perhaps, action recognition recreates motor-brain-area motor action {direct-matching hypothesis}. Perhaps, perceptual brain areas analyze perceptions by context, body parts used, and motions caused {visual hypothesis} [Ramachandran, 2004] [Rizzolatti et al., 1996].
Frontal-lobe regions {orbitofrontal cortex} {Brodmann area 11} can be above eye orbit bones, be for smell and affective values, and process learned stimulus-reward associations. It develops before prefrontal cortex.
Brain regions near eye {orbito-frontal lobe} can be for planning, priorities, unexpected, and attention.
A frontal-lobe region {premotor frontal lobe}, Broadmann area 6, between medial motor cortex and dorsomedial prefrontal cortex, stops movements, blocks repetition, coordinates muscles, and is for rehearsal before action or imagination.
Frontal-lobe rostral regions {rostral frontal lobe} can connect to thalamus, hypothalamus, and septum. Rostral frontal lobe is for inherited and acquired social behavior. Large rostral frontal-lobe lesions cause little attention to others' feelings and behavior, failure to greet friend or newly introduced stranger appropriately, emotionless conversation, and failure to say good-bye properly.
Prefrontal regions {supplementary motor area} (SMA), between medial motor cortex and dorsomedial prefrontal cortex, can receive from higher sense regions. SMA applies memories, goals, feelings, and will. It sends to premotor regions, which coordinate and integrate signals sent to motor cortex, and to midline, where brain sequences actions to fit plan {motor plan}. It has readiness potential and lateralized readiness potential.
In insula are hippocampus major {horn of Ammon} and hippocampus minor {hippocampus}| [Freund and Buzsáki, 1996] [Parra et al., 1998].
functions
Hippocampus is for long-term and short-term memory. It is necessary to store new memories, but conscious associative fact and event memory also requires other brain regions. Hippocampus is for motivation, reward, rehearsal, and space. It controls ergotropic behavior through sympathetic nervous system. It detects movement direction, head attitude with respect to body, and movement sequence. Neurons can find relations among facts and experiences. Neurons can find fact and experience conjunctions, while neocortex builds learning structures.
damage
Hippocampus damage blocks habituation to repeated stimulation. Hippocampal formation and parahippocampal cortex loss causes inability to consciously remember facts or events, such as new category members or unique examples. Damage does not affect perceptual-motor skills with no conscious internal representations, such as mastering task over several sessions or retrieving previously acquired factual knowledge. Hippocampus damage does not affect perception, consciousness, habits, skills, language, classical conditioning, instrumental conditioning, or motor control.
damage: Alzheimer's
In Alzheimer's disease, basal-forebrain cholinergic-neuron degeneration causes low hippocampal choline acetyltransferase activity.
input
Parahippocampal gyrus and hippocampus have multisensory cells.
output
Hippocampus sends through septum and nucleus accumbens to hypothalamus. It sends to cholinergic neurons at forebrain base, nucleus basalis magnocellularis, medial septal nucleus, and nucleus of diagonal band of Broca. It connects to medial temporal lobe.
process: memory
Brain stores memory only if cerebral neocortex sends information to three different areas close to hippocampus and then into hippocampus itself. Hippocampus then passes message back through medial temporal lobe to originating site in cerebral neocortex.
process: place
Spatial information travels from thalamus to neocortex to hippocampus. Hippocampus has non-topographic cognitive space map, stored in pyramidal place cells. Place-cell fields are stable and form in minutes [Brown et al., 1998]. Place cells increase firing when body is at that location [Ekstrom et al., 2003] [Frank et al., 2000] [Nadel and Eichenbaum, 1999] [O'Keefe and Nadel, 1978] [Rolls, 1999] [Scalaidhe et al., 1997] [Wilson and McNaughton, 1993] [Zhang et al., 1998]. Place cells also recognize textures, objects, and contexts. For example, they fire only when animal sees face (face cell), hairbrush, or hand.
waves
Hippocampus has 4-Hz to 10-Hz theta rhythm during active movement and alert immobility, synchronized between hemispheres in 8-mm region along hippocampus longitudinal axis. Other behaviors have local and bilaterally synchronous 40-Hz rhythm. A 200-Hz wave associates with alert immobility. Awake brain has synchrony, which increases with attention and preparation for motor acts. When neocortex desynchronizes with low-voltage rapid potentials, hippocampus synchronizes with theta waves. When neocortex synchronizes, hippocampus desynchronizes.
Frontal lobe has hippocampus major, hippocampus minor, and subiculum {hippocampal formation}.
Spatial information travels from thalamus to neocortex to hippocampus. Hippocampus has non-topographic cognitive space map, stored in pyramidal place cells. Some hippocampus neurons {place cell, hippocampus} increase firing when body is at that location [Ekstrom et al., 2003] [Frank et al., 2000] [Nadel and Eichenbaum, 1999] [O'Keefe and Nadel, 1978] [Rolls, 1999] [Scalaidhe et al., 1997] [Wilson and McNaughton, 1993] [Zhang et al., 1998]. Place-cell fields are stable and form in minutes [Brown et al., 1998]. Place cells also recognize textures, objects, and contexts. For example, they fire only when animal sees face (face cell), hairbrush, or hand.
Primate hippocampus has some neurons {spatial view cell} that fire only when viewing or recalling a location (with 30 degrees), no matter what head orientation or body location.
A brain region {limbic system}| {threshold system} {limbic lobe} on frontal-lobe interiors surrounds brainstem. In mammals, limbic system includes amygdala, caudate, cingulate gyrus, entorhinal cortex, fornix, hippocampus, hypothalamus, olfactory cortex, pyriform cortex, preoptic, putamen, septum, and thalamus. It receives from hypothalamus and basal ganglia. It sends to sense and motor cerebral cortex. It connects to sympathetic nervous system for activity and parasympathetic nervous system for relaxation.
Limbic system organizes essential drives, controls visceral processes, and involves emotions, fear, anger, flight, defense, and instincts. It does not integrate emotions.
evolution
Limbic system developed in primitive fish and is the most-ancient cerebral-hemisphere part. Limbic system is more important in mammals that rely on smell more than vision and less important in aquatic mammals and primates.
damage
Damage reduces cerebrum activity, and people enter dreamy state.
Body systems {mesolimbic system} can make cholecystokinin (CCK) peptide and dopamine (DA) catecholamine and send to other limbic system neurons in nucleus accumbens, lateral hypothalamus, ventral tegmentum, olfactory tubercle, and amygdala central nucleus. Schizophrenia causes mesolimbic-system hyperactivity.
Cerebrum rear {occipital lobe}| is for vision, perceptual judgment, memory, and association.
input
Occipital lobe receives from lateral geniculate nucleus, mostly onto layer 4 [Allman, 1998] [Allman and Kaas, 1971] [Zeki, 1974] [Zeki, 1993].
Layer 4 keeps input from two eyes separate. Alternating ocular-dominance-column bands, 0.5 millimeters wide, are for input from same ipsilateral side or opposite contralateral side.
Cortical layers above and below layer 4 have neurons that receive from both eyes. Binocular neurons differ slightly in eye connection alignment, allowing distance judgments.
Occipital lobe also receives from lower brain centers.
damage
Occipital lobe damage causes blindness. Cortical area V1, V2, and V3 damage affects perception and pattern recognition, leaving only ability to perceive intensity. Left-occipital lesion and corpus-callosum posterior-splenium lesion cause alexia without agraphia.
anatomy
Simple cells have well-defined excitatory and inhibitory regions in receptive fields [DeValois and DeValois, 1988] [Hubel and Wiesel, 1959] [Hubel and Wiesel, 1962] [Hubel, 1988] [Livingstone, 1998] [Spillman and Werner, 1990] [Wandell, 1995] [Wilson et al., 1990].
Complex cells do not have well-defined excitatory and inhibitory regions [Allman et al., 1985] [Gallant et al., 1997] [Lamme and Spekreijse, 2000] [Shapley and Ringach, 2000].
Complex-neuron receptive fields are larger than simple-neuron fields and have up to 100 degrees of visual angle.
processing
Some visual-cortex neurons distinguish between familiar and unfamiliar objects. Some neurons recognize faces. Some neurons respond only to face, hairbrush, or hand. Some neurons respond to face only if eyes point in direction. Some neurons store object locations. Some neurons predict eye-movement direction.
Visual-cortex layers 2 and 3 neuron groups {blob} and layers 4B, 5, and 6, separated by 0.4 to 1.0 millimeters, detect color and brightness, but not orientation, at space point [Conway et al., 2002] [Lennie, 2000] [Livingstone and Hubel, 1984] [Livingstone and Hubel, 1988] [Michael, 1978] [Michael, 1981]. Blob center-surround cells are for white-black and black-white, red-green and green-red opponent, and red-green and blue-yellow double opponent.
Visual-cortex layer-4 neurons {calcarine cortex} receive input from lateral geniculate nucleus and other brain sites. Cortical layers 3, 2, 1, and 6 repeat neural array in visual-cortex layer 4.
input
One quarter of neurons use input from right eye. One quarter use input from left eye. One quarter use input from both eyes with right eye dominant. One quarter use input from both eyes with left eye dominant.
Half have receptive fields with excitatory center. Half have inhibitory center.
Half are for shape and color detection. Half are for texture and motion detection.
100 billion neurons converge on 100 million output neurons in visual-cortex layer 5 and lower-4.
point processing
For space plane-surface points, brain has 30 neurons to detect features, such as line-segment orientation. The 30 neurons are in a circle and cover ranges, such as orientations.
receptive fields
Brain has neurons with different-size receptive fields, to detect different-size features, from point size, 0.1 millimeters, to whole-visual-field size, 1000 millimeters.
density
Neurons are denser at brain points corresponding to retina center and are less dense for retina edge.
maps
Visual cortex has maps for shape, depth, color, motion, and texture that interconnect. For features, visual cortex has repeated maps to represent different times in sequence.
number
Space plane-surface points have 4*2*2*30*5 = 2400 visual-cortex neurons. If point number is 1,000,000, then black-and-white representation requires 2,400,000,000 neurons. Color requires 7,200,000,000 neurons. If times differ by 200 milliseconds over three-second intervals, neuron number for visual information totals 100,000,000,000.
Occipital and temporal lobe region {circumstriate cortex} codes patterns and motion relations.
Visual-cortex superficial layers have color-sensitive neuron clusters {color blob}, at macrocolumnar intervals.
Region near ventral temporal lobe {dorsolateral visual area} {area DL} detects visual stimuli length, width, and stimulus position. It detects light-on-dark, dark-on-light, and contrast. It has large excitatory receptive fields, larger than optimum stimulus. It sends to inferotemporal cortex.
Occipital regions {ectosylvian visual area} can send to superior colliculi.
Around striate cortex are areas V2, V3, and V4 {extrastriate cortex, brain} [Bullier et al., 1994] [Hadjikhani et al., 1998].
Visual-cortex neurons respond to orientation, size, contrast, motion direction, motion speed, color, length, and depth {feature detector} in visual space. Neurons are switches that route messages, and states contain messages. Nerve signals from other neurons, muscles, and glands affect feature detectors. Feature detection is generalized associative learning, which can cause actions.
Visual association area 18, area 19, and posterior area 37 {inferior occipital lobe} bilateral damage prevents unique object recognition and feature retrieval. Area 18 and 19 bilateral damage prevents color perception.
Visual-cortex left striate region {intermediate medial hyperstriatum ventrale} (IMHV) is for filial imprinting.
Occipital regions {left posterior occipital lobe} can combine individual letters into one chunk {visual word form} and discriminate between words and non-words 200 milliseconds after input.
Words and pseudo-words, but not consonant strings, excite occipital region {left ventral occipital lobe}.
Occipital-lobe and parietal-lobe regions {occipito-parietal lobe} can be for thinking about two seen things simultaneously.
Occipital-lobe region {parastriate cortex} damage can cause blindness or word blindness.
Occipital-lobe area V4 and V4A region {posterior lunate sulcus} analyzes color and color constancy.
Occipital-lobe regions {posterior occipital lobe} can be for concrete low-complexity knowledge.
Occipital regions {posterior prestriate area} can attend to color, motion, or form.
Occipital regions {V1 brain area} {area V1} {primary visual cortex} {Brodmann area 17} {striate cortex} {striate occipital cortex} {area OC} can be for primary vision perception [Brewer et al., 2002] [Dantzker and Callaway, 2000] [Preuss, 2000] [Preuss et al., 1999] [Sawatari and Callaway, 2000] [Vanduffel et al., 2002].
input
Area V1 receives from lateral geniculate nucleus.
output
Area V1 sends feedback {shifter circuit, vision} to lateral-geniculate-nucleus left-and-right-eye layers, which excite or inhibit cortical-area activity [Ahmed et al., 1994] [Budd, 1998] [Douglas et al., 1995] [Felleman and Van Essen, 1991] [Fries, 1990] [LeVay and Gilbert, 1976] [Saint-Cyr et al., 1990] [Sherk, 1986] [White, 1989].
Area V1 sends orientation information to area V2 and then to area V5.
Area V1 sends object recognition and color information to area V2, then to area V4, and then to inferotemporal cortex.
Area V1 sends object location and movement information to area V2, then to area V5, and then to inferior parietal cortex.
Area V1, area V2, area V3, and mediotemporal cortex layer-5 pyramidal cells send to superior colliculus superficial layers and to pons nuclei.
Layer-6 pyramidal-cell axon collaterals synapse on aspinous inhibitory interneurons [Callaway and Wiser, 1996].
anatomy
Striate occipital cortex has visual-field map accurate to one millimeter. Map has ocular dominance columns for both eyes. Map has orientation columns, in which preferred orientation shifts through complete cycle in 0.5 to 1 millimeter. Thousands of orientation and ocular dominance columns cross each other at right angles. Neurons that prefer particular spatial frequency, color, or size also cluster [Engel et al., 1997] [Gur and Snodderly, 1997].
Around striate cortex are areas V2, V3, and V4 {extrastriate cortex, vision} [Bullier et al., 1994] [Hadjikhani et al., 1998].
processing: edge
Most area-V1 neurons respond best to one light or dark edge-or-thin-bar orientation. Edge or bar can be stationary, moving, or flashing.
processing: line
Concentric circles on retina are parallel lines in V1.
processing: letters
Area V1 is active while visualizing letters, even with eyes closed. V1 anterior part, for parafoveal input, is more active for large size letters. V1 posterior part, for foveal input, is more active for small size letters.
processing: binocular
Striate cortex combines signals from both eyes, as do most cells in visual cortex.
processing: attention
Attention affects area V1 [Brefczynski and DeYoe, 1999] [Fries et al., 2001] [Gandhi et al., 1999] [Ito and Gilbert, 1999] [Ito et al., 1995] [Kastner and Ungerleider, 2000] [Motter, 1993] [Niebur and Koch, 1994] [Niebur et al., 1993] [Niebur et al., 2002] [O'Connor et al., 2002] [Roelfsema et al., 1998] [Somers et al., 1999] [Watanabe et al., 1998].
factors: saccade
Spontaneous area-V1-neuron activity decreases when eye moves {saccadic suppression, V1} [Bridgeman et al., 1975] [Burr et al., 1994] [Castet and Masson, 2000] [Haarmeier et al., 1997] [Ilg and Thier, 1996] [McConkie and Currie, 1996].
Saccade target object excites some V1 cells and more V2 cells.
evolution
All mammals have areas V1 and V2, which combine visual, auditory, and tactile sense data. Perhaps, more trunk-and-neck flexibility and limb development allowed those areas.
Occipital regions {V2 brain area} {area V2} can be for stereoscopic vision [Engel et al., 1997] [Heydt et al., 2000] [Levitt et al., 1994] [Livingstone and Hubel, 1981] [Livingstone and Hubel, 1987] [Merigan et al., 1993] [Peterhans, 1997] [Roe and Ts'o, 1997] [Thomas et al., 2002] [Tootell et al., 1998] [Wong-Riley, 1994].
Almost all area V2 neurons receive input from both eyes. Color, location, and shape have alternating area-V2 bands. Nearness and farness cells detect distance. Area V2 neurons have bigger receptive fields than neurons in area V1. V2 neurons can respond to illusory edges, hidden and seen shapes, or figure-ground differences.
output
Almost as many neurons send to area V1 from area V2 as send from V1 to V2.
Occipital regions {V3 brain area} {area V3} can be for depth of vision [Burkhalter and Van Essen, 1986] [Lyon and Kass, 2002] [Newsome and Pare, 1988] [Newsome et al., 1986] [Newsome et al., 1989] [Tootell et al., 1997] [Zeki, 2003]. Nearness and farness cells detect distance. Some cortical-area-V3A neurons respond to gaze angle.
Ventral-system occipital regions {V4 brain area} {area V4} are for color perception and have topographic maps. Lunate sulcus posterior part and superior temporal sulcus anterior part are for color and color constancy. Area V4 responds to all wavelengths and line orientations but does not respond to movement. Some neurons are sensitive to spots or rectangles. Nearness and farness cells detect distance. Area-V4 visual neurons also respond to somatosensory stimuli [Burkhalter and Van Essen, 1986] [Newsome and Pare, 1988] [Newsome et al., 1986] [Newsome et al., 1989] [Tootell et al., 1997] [Wachtler et al., 2003] [Zeki, 1973] [Zeki, 1983] [Zeki, 1993]. Perhaps, cells are in color columns.
attention
Attention affects area V4 [DeWeerd et al., 1999] [Ghose and Maunsell, 2002] [McAdams and Maunsell, 1999] [Treue and Martinez-Trujillo, 1999].
color
Some cells are opponent, and some double-opponent. Some cells are for specific colors, orientations, and shapes. Some cells are for any color differences [DeValois and DeValois, 1975].
Ventromedial occipital-lobe regions {V6 occipital brain area} {area V6, occipital lobe} can be for color.
Ventral and medial occipital lobe region {ventromedial occipital lobe} damage causes color vision loss. Practice can reduce damaged region.
Ventral and posterior occipital regions {ventroposterior occipital lobe} {area VP} can be for color.
In occipital lobe, maps {visual buffer}, with retina input, can segregate figure from ground during perception and store images.
Vision cortex {visual cortex}| measures surface area and spatial frequency. It has same number of stellate neurons as pyramidal cells. Cerebral cortex has more than 30 visual or mixed areas, and half have maps with input from retina. Primates have more than 21 visual areas: V1, V2, MT, and M. V1 has calcarine fissure.
input
It receives excitatory axons one-third from same-side lateral geniculate nucleus and reticular nuclei. It receives inhibitory axons two-thirds from same-side locus coeruleus. It does not receive many axons from association areas or from other brain half.
output
It sends to superior colliculus, lateral geniculate nucleus, and area-17 and area-19 superficial pyramidal neurons, up to three millimeters away.
A brain region {parietal lobe}| between frontal and occipital lobes and above temporal lobe is for movement, orientation, calculation, and recognition. It controls symbol use, spatial orientation, maps, space in general, body-side consciousness, numerical and logical relations, and sense associations. It understands speech parts, passive voice, and possessive case, in different subregions. It is for language, learning, and memory. It, mostly inferior parietal, participates in memory retrieval.
Attention affects parietal lobe [Bisley and Goldberg, 2003] [Colby and Goldberg, 1999] [Gottlieb et al., 1998].
damage
Parietal lobe damage disrupts memory, spatial cognition, and attention. Parietal lobe damage causes anomalous body experiences. Non-dominant, usually right, posterior parietal lobe damage can cause hemi-neglect and anosagnosia.
Parietal lobe regions {angular gyrus}| can be for reading and writing, detect number concepts such as cardinality and ordinality, and connect speech-behavior auditory information to visual information. Perhaps, left side is multisensory, and right is spatial [Ramachandran, 2004]. Angular gyrus expanded greatly from mammals to humans.
Parietal-lobe regions {primary auditory cortex} {area A1} {A1 area} can be adjacent to Wernicke's area and receive from medial geniculate nucleus, which receives from inferior colliculus, which receives from nucleus {lateral lemniscus nucleus}, superior olive, and cochlear nuclei. Lateral lemniscus nucleus receives from superior olive and cochlear nuclei. Superior olive receives from dorsal, posteroventral, and anteroventral cochlear nuclei and both ears. Cochlear nuclei receive from cochlea {spiral ganglion} auditory neurons.
processing
Y cells maintain activity after moving object crosses receptive field, using cortico-thalamic feedback.
Parietal regions {auditory cortex}| can be for hearing, sound, octaves, and tone patterns. It has frequency-sensing neuron field perpendicular to intensity-sensing neuron field.
processing
Specific brain places recognize sounds in word, speech, or sentence. Special places are for object names, word productions, writing, remembering words, and speaking spontaneously.
No matter the musical scale, people prefer octave tuned slightly higher than exact 2:1 frequency ratio.
damage
Primary hearing area destruction causes only high-tone loss. Bats can hear even with damaged primary auditory areas.
Auditory-cortex regions {corticofugal network} can learn sound patterns and send dopamine feedback to itself and higher regions.
Parietal-lobe back regions {dorsal parietal lobe} can be for well-being feeling.
Cells {grasping cell} can respond to grasping.
Inferior parietal lobe regions {inferior parietal lobe} (IPL) {caudal inferior parietal lobe} can have two main parts, LIP and 7a. Both LIP and area 7a receive input from thalamus medial pulvinar nucleus. Area LIP sends to superior colliculus and frontal eye fields to execute saccadic eye movements. Area 7a sends to polymodal cortex, limbic system, and prestriate cortex, to detect retinal locations and eye and head positions. Right or left Brodmann-area-7 damage causes hemi-neglect.
Speech area damage {left anterior parietal lobe} can harm syntax, sequential organized speech, and skilled movements but not affect phoneme, word, logic, or grammar production or understanding.
Left inferior parietal region {left inferior parietal} damage affects color-perception achromatopsia in fusiform gyrus, motion-perception akinetopsia in mediotemporal region, face perception in prosopagnosia, and feelings that there are imposters in Capgras syndrome [Nordby, 1990] [Perrett et al., 1992] [Scalaidhe et al., 1997] [Tranel and Damasio, 1985].
Association area {left inferoparietal} damage can cause various language problems.
Association area {left parieto-occipital} damage can cause various language problems.
Speech area damage {left posterior parietal lobe} can interfere with language acquisition and harm paradigmatically-organized speech production and understanding, but not affect syntax and organized speech.
Posterior area V4 and V4A regions {lunate sulcus} can analyze color and color constancy.
Human parietal-lobe regions {motor cortex}| {area M1} {Brodmann area 4} {precentral gyrus} {pre-central gyrus} {motor strip} can have two or three million motor neurons, control purpose, initiate voluntary movements, activate habits, cause automatic movements, and specify muscle positions needed at movement completion. Pre-central gyrus contains most corticospinal motor tract neurons.
output
Motor-cortex pyramidal neurons send to extrapyramidal-motor-system alpha and gamma motor neurons, to coordinate and initiate fast and precise movements. Motor neurons excite spinal cord neurons, which excite special muscle fibers in muscle spindles. Primary motor cortex connects to basal ganglia, thalamus, and other cerebral cortex [Bullock et al., 1977].
processing
Muscles move to reach specified muscle positions, as registered by muscle sensors. Motor cortex programs movements by controlling lower-level reflexes. Once started, motor program cannot stop, only change. Motor cortex neurons align by movement direction. Neurons signal particular limb-movement direction. Actual movement is sum of vectors. Primary motor cortex M1 activity shifts with intended-arm-movement coordinates [Amirikian and Georgopoulos, 2003] [Bullock, 2003] [Dean and Cruse, 2003] [Evarts, 1968] [Miall, 2003].
In isotonic movement, motor cortex and red nucleus neurons give intense burst, at frequency corresponding to movement velocity and duration corresponding to movement duration. In isotonic movement, Purkinje cells give bursts or pauses, to inhibit positive feedback to antagonists or allow positive feedback to agonists. In isometric movement, motor cortex and red nucleus neurons give intense burst, at frequency corresponding to force and duration corresponding to force rate. Motor cortex and red nucleus neurons can also have tonic output.
Sense information selects motor-program parameters to initiate program, to define movement endpoint through proprioception, and to guide subsequent adaptive process that mediates motor learning. Sense feedback shapes motor map, and vice versa.
Y cells maintain activity after moving object crosses receptive field, using cortico-thalamic feedback.
Muscle activity initiation always begins unconsciously in cerebrum. Conscious control can affect final motor nerve signals.
damage
Damage to motor cortex does not change learned mammal behavior patterns.
voluntary movement
Mammals have voluntary behavior and move bodies and appendages to specific space points {voluntary movement}.
voluntary movement
The two million motor neurons of human parietal-lobe motor-cortex area M1 initiate voluntary movements and specify muscle positions needed after movements. Muscles move to reach specific muscle positions, as registered by muscle sensors. Motor-cortex pyramidal neurons send to spinal-cord lateral corticospinal tract, which controls voluntary muscles by controlling reflexes.
vectors
Motor-cortex neurons contract specific muscle fibers, which move in relative direction from zero length change up to maximum length change. Fiber movements have magnitude and direction and so are vectors.
vector sums
Individual cortical cells have few connections to nearby neurons, so individual-neuron activation cannot provide enough signal strength to start or maintain movements {motor act}. Motor acts require multiple neuron pathways to achieve precise movement timing. Motor acts generate large precisely coordinated temporal-signal sequences to activate muscles. In contralateral superior colliculus, average neuron vector directs eye movement, or eye and head movement, to target object, using body-centered coordinates.
Neurons for attention to target control motor neurons. Brains control movements using few independent parameters. Motor acts require coordinated temporal motor-neuron activation and inhibition. To move limbs or body parts in specific directions, motor-cortex neurons contribute fiber movement. Total limb or body-part movement is sum of vectors and moves limb or body part from starting position to final position, using body-centered coordinates. Motor cortex accounts for starting position, finds vector sum, and moves to intended final position. Proprioceptive sense information defines starting and ending positions [Amirikian and Georgopoulos, 2003] [Bullock, 2003] [Dean and Cruse, 2003] [Miall, 2003].
input
Input from attention, planning, and drive neurons goes to all motor neurons.
movement-control parameters
Movement control uses several independent parameters. For isotonic movements with constant force, motor-cortex neurons fire for duration corresponding to movement duration, at rate corresponding to movement velocity. For isometric movements with no motion, motor-cortex neurons fire for duration corresponding to force duration, at rate corresponding to force.
In primates, parietal regions {area MT} {MT area} can analyze small object and large background motions and orientation. Adjacent neurons detect slightly different orientations in one direction and opposite orientations in perpendicular direction. MT also participates in recognition memory.
Parietal-lobe anterior-edge regions {post-central gyrus} can be tactile and kinesthetic sense areas. Its SI topographic map has Penfield homunculus.
Parietal lobe has posterior region {posterior parietal lobe} (PP) [Andersen, 1995] [Batista and Andersen, 2001] [Bisley and Goldberg, 2003] [Bruce et al., 1986] [Colby and Goldberg, 1999] [Glickstein, 2000] [Gross and Graziano, 1995] [Snyder et al., 2000].
input
Posterior parietal lobe receives from visual, auditory, and proprioceptive cortex.
output
Posterior parietal lobe sends to inferior-temporal-lobe superior temporal sulcus superior boundary, spinal cord, brainstem, prefrontal lobe, and frontal lobe.
functions
Posterior parietal lobe detects sense location, size, orientation, and motion direction. It represents attended object locations. It is for attention, shape transformations, category and spatial coordinate interactions, spatiotopic mapping, and spatial relations. In humans, it is about spatial cognition, in right hemisphere, and language understanding, in left hemisphere. It registers movement consequences, such as current eye position. Eye position multiplies receptive-field event [Zipser and Andersen, 1988]. It plans and initiates limb movements in primates. Map in cortical area 6 computes locations in nearby space, using body-based coordinates, and can guide orienting responses, like tectofugal pathway. Cortical area 7b has map of nearby space for motor control. Neurons respond to both receptive field changes and eye or head position [Andersen et al., 1985] [Andersen et al., 1997] [Pouget and Sejnowski, 1997] [Salinas and Abbott, 1995].
Parietal regions {suprasylvian visual area} can send to superior colliculi.
In primates, left-inferior parietal-lobe association regions {Wernicke's area} {Wernicke area} can be in left-superior temporal lobe below lateral fissure, next to primary auditory cortex, at vision, audition, and somaesthetic cortical junction. Wernicke's area has no connections to limbic system. Broca's area and Wernicke's area connect through arcuate fasciculus.
damage
Wernicke's area damage causes alexia, agnosia, tactile aphasia, and word deafness but does not affect writing or hearing. Disconnecting Wernicke's area from motor centers causes apraxia. Wernicke's aphasia causes bad semantics, paraphasia, imprecise words, circumlocutions, and neologisms, but speech is fluent, rapid, articulated, and grammatical.
Cerebral neocortex {prefrontal lobe}| {prefrontal cortex} can be behind frontal lobe [Carmichael and Price, 1994] [Fuster, 1997] [Goldberg, 2001] [Grafman et al., 1995] [Miller and Cohen, 2001] [Passingham, 1993] [Preuss, 2000].
functions
Prefrontal lobe activates brain, is for attention, is for emotion cognition, controls respiration and autonomic system, causes initiative and persistence, foresees consequences, and forms intentions.
Lateral prefrontal cortex is for temporary storage in working memory. Anterior cingulate in medial prefrontal cortex is for executive functions and coordinates information about self. Ventral prefrontal and orbital cortex is for emotions and participates in memory retrieval.
input
Prefrontal lobe has many dendrite D1 and D5 dopamine receptors. Prefrontal cortex receives from mediodorsal thalamic nucleus.
output
Of all neocortex, only prefrontal sends directly to hypothalamus. It also sends to basal ganglia striatum and globus pallidus.
damage
Prefrontal lobe damage causes selfishness, bad manners, inability to concentrate, failure to plan, inability to think abstractly, and indifference.
evolution
Lateral prefrontal cortex is only in primates. Ventral prefrontal lobe, orbital cortex, and medial-prefrontal-cortex anterior cingulate are only in mammals.
Brain top and side regions {dorsolateral prefrontal cortex} can be for spatial coordinates and categorization. It looks up information in associative memory to access stored information for working memory. It uses model similar to cerebellar model to control muscle movement and learn new physical skills.
attention
Dorsolateral prefrontal cortex, cingulate nucleus, frontal eye fields in area 8, posterior parietal lobe in area 7a, pulvinar nucleus, and superior colliculus shift attention.
rule
Ventrolateral prefrontal cortex, Brodmann areas 44, 45, and 47, and dorsolateral prefrontal cortex, Brodmann areas 9 and 46, process conditionals. They develop after orbitofrontal cortex and before rostrolateral prefrontal cortex. Orbitofrontal cortex processes rules.
task
Rostrolateral prefrontal cortex, Brodmann area 10, can process task sets. It develops after dorsolateral and ventrolateral prefrontal cortex.
Prefrontal regions {prefrontal medial subgenual region} can be for meaning and mood.
Prefrontal regions {prefrontal ventromedial cortex} can be for sense integration.
Side brain regions {temporal lobe}| can receive information about features, orientations, balance, and sound and have speech-recognition systems. Inside area is for short-term memory, affective memory, and association.
input
Middle-temporal-lobe V5 area detects pattern directions and speed gradients. Medial superior temporal lobe dorsal area detects heading. V2 and V4 areas detect non-luminance-contour orientations. V4 area detects curved boundary fragments. Inferotemporal lobe (IT) detects shape parts. IT and CIP detect curvature and orientation in depth from disparity.
output
Temporal lobe sends to limbic system.
damage
Temporal-lobe lesions can cause the feeling that one has previously witnessed a new situation. Temporal lobe removal decreases pattern discrimination, color vision, fear reactions, learning sets, and retention. Temporal lobe electrical stimulation causes fear, sadness, or loneliness. Removing both temporal lobes makes monkeys fail to recognize objects, be hypersexual, exhibit compulsive oral behavior, not be afraid of things that used to cause fear, and be less aggressive {Klüver-Bucy syndrome, monkey} [Klüver, 1933].
Anterior and inferior temporal-lobe region {anterior inferotemporal area} {area TE} responds to color, shape, and texture over large areas. It detects curves, corners, blobs, and other features. It receives from posterior inferotemporal and medial temporal and sends to prefrontal, medial temporal, and striatum. It has no topographic maps. Eye or head movements do not affect it [Wang et al., 1996].
Temporal-lobe {anterior temporal lobe} damage can block fact retrieval and affect speech.
Extrastriatal gyrus {fusiform gyrus}| in middle and inferior ventral temporal lobe and ventral occipital lobe stores categories, shapes, and patterns. Fusiform gyrus contains area V4, which detects color. A fusiform-gyrus region {fusiform face area} can detect faces [Cowey and Heywood, 1997] [Damasio et al., 1980] [Gallant et al., 2000] [Hadjikhani et al., 1998] [Haxby et al., 2000] [Kanwisher et al., 1997] [Meadows, 1974] [Ramachandran, 2004] [Sakai et al., 1995] [Tong et al., 2000] [Tootell and Hadjikhani, 2001] [Vuilleumier et al., 2001] [Wade et al., 2002] [Zeki, 1990] [Zeki et al., 1991] [Zeki et al., 1998].
damage
Fusiform and lingual gyri damage causes no color perception.
Brain has inferior temporal cortex region {inferotemporal cortex}| (IT) [DiCarlo and Maunsell, 2000] [Gross, 1998] [Gross, 2002] [Logothetis and Sheinberg, 1996] [Tamura and Tanaka, 2001] [Tanaka, 1996] [Tanaka, 1997] [Tanaka, 2003] [Tsunoda et al., 2001] [Wang et al., 1996] [Young and Yamane, 1992].
functions
IT affects visual recognition by visual cortex. IT analyzes complex visual stimuli and discriminates visual forms. IT is for attention and visual memory. IT selects object to view.
IT responds best to new stimuli. If new visual feature matches the original, brain suppresses half of inferotemporal neurons activated by visual feature. One-third of inferotemporal neurons decrease response to familiar or repeated stimuli.
Some inferotemporal neurons recognize individual faces at different views, face prototypes, or poses, ignoring brightness.
Some inferotemporal neurons respond to stimulus actively held in memory and receive back projections from prefrontal cortex [Miyashita et al., 1996] [Naya et al., 2001] [Sheinberg and Logothetis, 2001].
input
IT receives from dorsolateral visual area.
output
IT sends to object recognition centers and attention and orientation systems.
damage
Inferior temporal lobe damage causes inability to categorize or discriminate.
Area 20 and 21 {left anterior inferotemporal} damage impairs object naming, though people can describe objects, have good grammar and phonetics, and name actions and relationships [Wang et al., 1996].
Temporal pole {area 38} {left anterior temporal lobe} damage impairs object naming, though people can describe objects, have good grammar and phonetics, and name actions and relationships.
Verbal-acoustic areas {left temporal lobe} can be for phoneme and word understanding.
Temporal regions {middle temporal lobe} {medial temporal lobe} (MT) {mediotemporal cortex} {V5 brain area} {area V5} can encode motion perception and respond to movement and movement direction but not to wavelength. MT can detect movement direction, from visual texture [Albright, 1993] [Allman and Kaas, 1971] [Andersen, 1997] [Britten et al., 1992] [Britten et al., 1996] [Cook and Maunsell, 2002] [Ditterich et al., 2003] [Goebel et al., 1998] [Goldstein and Gelb, 1918] [Heeger et al., 1999] [Hess et al., 1989] [Heywood and Zihl, 1999] [Huk et al., 2001] [Humphreys, 1999] [Mather et al., 1998] [Parker and Newsome, 1998] [Salzman and Newsome, 1994] [Salzman et al., 1992] [Schall, 2001] [Shadlen et al., 1996] [Tootell and Taylor, 1995] [Tootell et al., 1995] [Tolias et al., 2001] [Williams et al., 2003] [Zeki, 1974] [Zeki, 1991] [Zihl et al., 1983].
MT neurons can code for depth [Bradley et al., 1998] [Cumming and DeAngelis, 2001] [DeAngelis et al., 1998] [DeAngelis and Newsome, 1999] [Grunewald et al., 2002] [Maunsell and Van Essen, 1983].
memory
Medial temporal lobe stores long-term declarative explicit memories. MT also participates in recognition memory.
attention
Attention affects medial temporal lobe [McAdams and Maunsell, 2000] [Saenz et al., 2002] [Treue and Martinez-Trujillo, 1999].
anatomy
MT includes amygdala, entorhinal cortex, hippocampus, parahippocampal gyrus, perirhinal cortex, and Brodmann areas 28, 35, 36, and 37.
input
MT receives from V1 and superior colliculus. Parahippocampal and perirhinal cortex both receive from somatic, auditory, and visual sensory cortex. Entorhinal cortex receives from parahippocampal and perirhinal cortex. Hippocampus DG region receives most from entorhinal cortex and some from parahippocampal and perirhinal cortex, not from neocortex. Hippocampus CA3 receives from DG. Hippocampus CA1 receives from CA3. Subiculum, in hippocampal formation, receives from CA1.
output
MT sends to superior colliculus, posterior parietal lobe, lateral intraparietal lobe, ventral intraparietal lobe, medial superior temporal lobe, and frontal lobe. MT connects through pons nuclei to cerebellum to control body and eye movements. Subiculum sends to rhinal cortex, which sends to sensory cortex.
damage
MT damage over wide area impairs factual knowledge retrieval but not information about categories or object features. Damage impairs smell but nothing else. Damage does not affect attention. Damage also affects emotions. Damage causes retrograde amnesia and affects all senses.
evolution
All primates have visual area 5.
Middle superior temporal region {optical flow field} {middle superior temporal area} (MST) encodes motion perception, especially texture flows.
Lateral temporal regions {non-medial temporal region} can include polar region, inferotemporal area, and posterior parahippocampus and retrieve factual knowledge, but not skill, perception, or motor control.
Region near hippocampus {parahippocampal area} includes rhinal cortex, with medial temporal lobe memory system and multisensory convergence. Parahippocampal area region {parahippocampal place area} responds most to places, not objects.
Cortex near nose {perirhinal cortex} damage causes inability to consciously remember facts or events, such as new category members or unique examples. Damage does not affect perceptual-motor skills with no conscious internal representations, such as mastering task over several sessions or retrieving previously acquired factual knowledge.
Posterior inferior temporal region {posterior inferotemporal cortex} (PIT) receives from ventral-pathway area V4 and sends to anterior inferotemporal cortex. Attention affects it [DeWeerd et al., 1999].
Posterior superior temporal regions {posterior superior temporal lobe} can be at temporal-occipital-parietal junction, be for associative memory, and retrieve representations and concepts [Bruce et al., 1986].
Posterior temporal-lobe regions {posterior temporal lobe} can be for consonant strings, words, speech fluency, and categorical knowledge. Visual association area-18, area-19, and posterior-area-37 bilateral damage prevents unique object recognition and feature retrieval.
Right temporal lobe region {right temporal lobe} controls spatial relationships, form manipulations, and visual discriminations.
Superior temporal lobe gyrus {superior temporal gyrus} represents sounds.
Superior temporal lobe sulcus {superior temporal sulcus} (STS) detects head or face movement, separate from viewing angle or recognition. Anteriorly, in area V4 and V4A, it analyzes color and color constancy. It detects shapes and textures. Posterior cingulate, medial frontal gyrus, and superior temporal sulcus are about imagining how other people feel.
Temporal regions {V6 temporal brain area} {area V6, temporal lobe} can be for locations.
Ventral temporal-lobe regions {ventral temporal lobe} can control attention and consciousness.
Central brain spaces {ventricle, brain}| are down middle, hold cerebrospinal fluid, and connect to spinal cord fluid tube. Beneath septum pellucidum, first two ventricles connect through hole to third ventricle, which is between right and left hypothalamus lobes. Tectum covers third ventricle in back. In front of third ventricle are septal and preoptic areas. Fourth ventricle is in hindbrain.
Fourth-ventricle aqueduct {cerebral aqueduct} is in midbrain.
Almost transparent tissue {septum pellucidum}, in cerebrum beneath corpus callosum, separates first and second ventricles.
Forebrain neural activities can correlate with sense qualities {neuronal correlates of consciousness}| (NCC) [Alauddin et al., 2003] [Calvin, 1996] [Calvin, 1996] [Calvin, 1998] [Cotterill, 1998] [Changeux, 1983] [Crick and Koch, 1992] [Crick and Koch, 2003] [Crick, 1979] [Crick, 1994] [Dehaene and Changeux, 2004] [Dehaene and Naccache, 2001] [Dehaene, 2001] [Dehaene et al., 2003] [Dragunow and Faull, 1989] [Fried et al., 1998] [Graziano et al., 2002] [Greenfield, 1995] [Greenfield, 2000] [Han et al., 2003] [Jasper, 1998] [Koch and Davis, 1994] [Koch, 2004] [Lechner et al., 2002] [Li et al., 2002] [Llinás et al., 1998] [Slimko et al., 2002] [Taylor, 1998] [Yamamoto et al., 2003].
brain processes
Consciousness is not about brain processes, because they are at low level. Algorithm high-level code must use low-level code for processor. Brain processes do not yet reveal higher code or algorithm.
brain regions
Consciousness can be a whole-brain, many-connected-region, few-connected-regions, or one-brain-region property [Chalmers, 2000] [Metzinger, 2000] [Mollon and Sharpe, 1983] [O'Regan and Noë, 2001] [Pessoa et al., 1998] [Teller, 1984] [Teller and Pugh, 1983].
Perhaps, brain has sets of different neurons, whose information, interactions, or processing is necessary and/or sufficient for consciousness aspects.
Awakeness depends on nuclei below cortex and thalamus that excite, or remove inhibition from, cortex and thalamus non-specifically, but these nuclei do not directly make sense qualities.
Sense qualities depend on cortex and thalamus, but cortex and thalamus regions project to local or distant cortex and thalamus locations, so no region relates to sense qualities.
complexity
Many non-conscious processes involve complex computations, and brain can learn complex non-conscious processes. Many widespread brain processes have no association with consciousness. Both unconscious and conscious processes involve neurons with high firing rates and/or large chemical changes.
feedback
Perhaps, consciousness requires feedback in brain pathways. Illusions can switch between two different sense qualities or perceptions about same figure or image. Perception depends on memory and thalamocortical feedback.
iteration
Perhaps, experience involves iteration, but repetition delays processing and limits discrimination.
Probably, experience does not use iteration, repetition, waves, vibrations, oscillations, or anything periodic, because such processing limits information.
mind requirements
Consciousness requires information from objects and events outside brain, information transfer from receptors to processors, and effector controls. Information channels from objects and events to brain to effectors must have enough information capacity and speed. Channels have reverse channels to provide feedback and synchronization. Information codes must express all physical relations.
physiology
Perhaps, cell membrane polarizations and depolarizations; chemical concentration changes from manufacture, destruction, or transfer; or cell structure changes at synapses or dendrites have biochemical and biophysical effects that cause experience. Perhaps, brain-pathway cellular-connection changes cause experience. Consciousness-causing activity must last long enough to allow integration and be short enough to prevent signal overlap. Neuron activity affects other neurons, so correlations can be widespread and indirect.
similar neurons
Perhaps, brain has "consciousness neurons" that have similar ion channels, shapes, receptors, axons, synapses, and/or biochemistry. Perhaps, some neuron feature is necessary and/or sufficient for consciousness aspects. However, no neuron properties or events, including connections, directly relate to sense qualities.
Testing visual nerve pathways {visual pathways} can reveal neural activity related to visual sense qualities. Consciousness uses brain regions for attention, shape, and planning and goals [Chalmers, 2000] [Ffytche, 2000] [Kanwisher, 2001] [Lumer, 2000] [Lumer et al., 1998].
Scientists know visual pathways better than other sense pathways [Andersen et al., 1990] [Baizer et al., 1991] [Barbas, 1986] [Felleman and Van Essen, 1991] [Karnath, 2001] [Kennedy and Bullier, 1985] [Lewis and Van Essen, 2000] [Maunsell and Van Essen, 1983] [Rockland and Pandya, 1979] [Saleem et al., 2000] [Salin and Bullier, 1995] [Van Essen and Gallant, 1994] [Zeki and Shipp, 1988].
visual pathway level 01
Level 01 is from Retina to Lateral Geniculate Nucleus [LGN]. Damage affects sight, but processing is not sufficient for consciousness. Though retinal-cell distribution causes lower visual acuity outside fovea, sense qualities do not seem to have much lower acuity. Only two color-receptor types are in fovea, but sense qualities seem to have all colors. Few color receptors are outside fovea, but sense qualities seem to have all colors. Though retina has blind spot, people do not notice it. Eye movements can cause fuzziness, but sense qualities do not show much blurring. Blinking can cause darkness, but sense qualities are not black then.
visual pathway level 02
Level 02 is LGN, in Thalamus, to area V1. Damage affects sight, but processing is not sufficient for consciousness. LGN modulates stimuli received from retina, so it does not determine sense qualities, because retina does not.
visual pathway level 03
Level 03 is Superior Colliculus [SC] to LGN. Damage does not affect sight. SC just controls saccades.
Level 03 includes Pulvinar Nucleus and other brainstem nuclei to areas V1, V2, and SC. Damage does not affect sight. Brainstem nuclei just control gaze, pupil size, blinking, and daily rhythms.
Level 03 includes area V1 or Brodmann 17, in dorsal and ventral pathways, to areas V2, V3, PIP, V3A, PO, V4t, V4, MT, and MSTl. Damage affects sight, but processing is not sufficient for consciousness. Area V1 codes motions and objects separately, but these unite in sense qualities. People do not use V1 in dreams, which have sense qualities. V1 neuron responses stay the same when ambiguous-figure sense qualities alternate. V1 neuron responses can change with unconscious blinking, eye movement, and fast color alternation, though sense qualities stay the same.
visual pathway level 04
Level 04 is area V2, V2 dorsal [V2d], and V2 ventral [V2v], in dorsal and ventral pathways, to areas V3, VP, PIP, V3A, PO, V4, V4t, VOT, VIP, MSTd, MSTl, FST, and FEF. Damage affects sight, but processing is not sufficient for consciousness. V2 codes shape, contrast, depth, motion, edges, and figure separately, but these unite in sense qualities.
visual pathway level 05
Level 05 includes areas V3, V3 dorsal [V3d], and V3 ventral [V3v] in dorsal pathway to PIP, V3A, PO, MT, V4t, V4, VIP, LIP, MSTd, FST, FEF, and TF. Processing is not sufficient for consciousness. V3 codes for fast response, not object images.
Level 05 includes Ventral Posterior [VP], in ventral pathway, to PIP, V3A, PO, MT, V4, VOT, VIP, LIP, FST, FEF, and TF. Processing is not sufficient for consciousness. VP neuron responses reflect both retinal stimulation and sense qualities.
Level 06 includes Posterior Intraparietal [PIP] and Posterior Parietal complex [PPcx], in dorsal pathway, to PO, MT, V4, DP, and 7a. Processing is not sufficient for consciousness. PIP just controls attention.
visual pathway level 06
Level 06 includes V3A, in ventral pathway, to PO, MT, V4, DP, LIP, MSTd, MSTl, FST, and FEF. Processing is not sufficient for consciousness. V3a codes only for shape, but sense qualities include other features.
Level 07 includes Medial Dorsal Parietal [MDP], in dorsal pathway, to PO and 7a. Processing is not sufficient for consciousness. MDP codes for fast response, not object images.
visual pathway level 07
Level 07 includes Medial Intraparietal [MIP], Intraparietal dorsal [IPd], and Intraparietal anterior [IPa], in dorsal pathway, to PO and 7a. Processing is not sufficient for consciousness. MIP codes for fast response, not object images.
Level 07 includes Parietal-Occipital [V6] [PO], PO anterior [POa], PO anterior-internal [POa-i], PO anterior-external [POa-e], Lateral Occipital Parietal [V7] [LOP], Lateral Occipital Caudal [LOC], and Dorsal Medial Occipital complex [DMOcx], in dorsal pathway, to MDP, MIP, MT, V4t, DP, VIP, LIP, MSTd, MSTl, 7a, and FEF. Processing is not sufficient for consciousness. PO codes for fast response, not object images.
Level 07 includes Medial Temporal [V5] [MT], MT caudal [MTc], Temporal A [TA], TA anterior [TAa], Temporal E [TE], TE anterior [TEa], TE medial [TEm], TE antero-dorsal [TEa-d], TE antero-ventral [TEa-v], TE anterior-medial [TEa-m], TE1, TE2, TE3, TE1-3, TE1-3 dorsal [TE1-3d], TE1-3 ventral [TE1-3v], and Temporal E Occipital [V8] [TEO], in dorsal and ventral pathways, to PO, V4t, V4, VIP, LIP, MSTd, MSTl, FST, FEF, 46, and Prefrontal. Processing is for objects. Most neurons are about perception.
Level 07 includes V4 transitional [V4t], V4t anterior [V4ta], and V4t posterior [V4tp], in ventral pathway, to PO, MT, V4, MSTd, MSTl, FST, and FEF. Cells can track sense qualities and unsensed alternative-figure perception.
Level 07 includes V4, in ventral pathway, to MT, V4t, DP, VOT, LIP, FST, PITd, PITv, FEF, CITd, CITv, AITv, 46, TF, and TH. Cells can track sense qualities and unsensed alternative-figure perception.
visual pathway level 08
Level 08 includes Dorsal Prelunate [V7] [DP], in dorsal pathway, to LIP, MSTd, MSTl, FST, 7a, FEF, and 36. Processing is not sufficient for consciousness. DP codes for fast response, not object images.
Level 08 includes Ventral Occipital Temporal [V8] [VOT], Occipital Temporal A [OA], and OA anterior [OAa], in ventral pathway, to PITd and PITv. Processing is for space.
visual pathway level 09
Level 09 includes Ventral Intraparietal [VIP], VIP*, VIP lateral [VIPl], and VIP medial [VIPm], in dorsal pathway, to LIP, MSTd, MSTl, FST, 7a, and FEF. Processing is not sufficient for consciousness. VIP codes for fast response, not object images.
Level 09 includes Lateral Intraparietal [LIP], LIP dorsal [LIPd], and LIP ventral [LIPv], in dorsal pathway, to VIP, MSTd, MSTl, FST, 7a, FEF, 46, and TF. Processing is not sufficient for consciousness. LIP codes for fast response, not object images.
Level 09 includes Medial Superior Temporal dorsal [MSTd], MSTd anterior [MSTda], and MSTd posterior [MSTdp], in dorsal pathway, to VIP, LIP, FST, PITd, PITv, 7b, 7a, FEF, STPp, and TF. Processing is not sufficient for consciousness. MSTd codes for fast response, not object images.
Level 09 includes Medial Superior Temporal lateral [MSTl], MST medial [MSTm], and MST complex [MSTcx], in dorsal pathway, to VIP, LIP, FST, 7a, FEF, and STPp. Processing is not sufficient for consciousness. MSTl codes for fast response, not object images.
Level 09 includes Floor of Superior Temporal [FST], Ventral Superior Temporal [VST], and VST complex [VSTcx], in ventral pathway, to VIP, LIP, MSTd, MSTl, PITd, PITv, 7a, FEF, STPp, and TF. Processing is for space.
Level 09 includes Posterior Inferior Temporal dorsal [PITd] and Inferior Temporal complex [ITcx], in ventral pathway, to FST, PITv, FEF, CITv, AITd, AITv, and 46. Cells track whether sensation is on or off.
Level 09 includes Posterior Inferior Temporal ventral [PITv], in ventral pathway, to FST, PITd, FEF, CITd, CITv, AITd, AITv, TF, and TH. Cells track whether sensation is on or off.
visual pathway level 10
Level 10 includes Brodmann 7b [7b], in dorsal pathway, to 7a, STPp, and 36. Processing is not sufficient for consciousness. 7b codes for fast response, not object images.
Level 10 includes Brodmann 7a [7a] and 7a lateral, in dorsal pathway, to 7b, FEF, STPa, AITd, 36, 46, TF, and TH. Processing is not sufficient for consciousness. 7a codes for fast response, not object images.
Level 10 includes Frontal Enterofrontal [Brodmann 8] [FEF], in dorsal and ventral pathways, to 7a, STPp, CITd, CITv, AITd, and 46. FEF integrates fast responses and object perception.
Level 10 includes Superior Temporal Parietal posterior [STPp], Temporal-parietal [Tpt], Temporal-Parietal-Occipital [TPO], TPO caudal [TPOc], TPO intermediate [TPOi], TPO rostral [TPOr], Parietal Temporal G [PG], and PG anterior [PGa], in dorsal and ventral pathways, to 7b, FEF, CITd, CITv, STPa, 46, TF, TH, Striatum, and Prefrontal. Processing is for space, shape, and texture, but STPp has no topographic maps.
Level 10 includes Caudal Inferior Temporal dorsal [CITd], in ventral pathway, to FEF, STPp, AITd, AITv, 46, and TH. Processing is for shape and texture, but STPp has no topographic maps.
Level 10 includes Caudal Inferior Temporal ventral [CITv], in ventral pathway, to FEF, STPp, AITd, AITv, 46, TF, and TH. Processing is for shape and texture, but STPp has no topographic maps.
visual pathway level 11
Level 11 includes Superior Temporal Parietal anterior [STPa], in dorsal and ventral pathways, to AITd, 36, 46, TF, TH, 35, ER, Striatum, and Prefrontal. Processing is for shape and texture, but STPp has no topographic maps.
Level 11 includes Anterior Inferior Temporal dorsal [AITd], in ventral pathway, to STPa, 36, 46, TF, TH, Striatum, and Prefrontal. Processing is for shape and texture, but STPp has no topographic maps.
Level 11 includes Anterior Inferior Temporal ventral [AITv], in ventral pathway, to STPa, 36, 46, TF, TH, 35, HC, Striatum, and Prefrontal. Processing is for shape and texture, but STPp has no topographic maps.
visual pathway level 12
Level 12 includes Brodmann 36 [36], in dorsal pathway, to Brodmann 46, TF, TH, 35, ER, and HC. Processing is not sufficient for consciousness. Brodmann 36 codes for fast response, not object images.
Level 12 includes Brodmann 46 [46], in dorsal and ventral pathways, to Brodmann 36, TF, TH, and ER. Brodmann 46 integrates fast responses and object perception.
Level 12 includes Temporal F [TF], in ventral pathway, to Brodmann 36, 46, and ER. Processing is about high-level object perception.
Level 12 includes Temporal H [TH], in ventral pathway, to Brodmann 36, 46, and ER. Processing is about high-level object perception.
visual pathway level 13
Level 13 is Brodmann 35 [35], in dorsal pathway, to ER. Processing is not sufficient for consciousness. Brodmann 35 codes for fast response, not object images.
visual pathway level 14
Level 14 is Entorhinal area [ER], in dorsal and ventral pathways, to HC. ER integrates fast responses and object perception.
visual pathway level 15
Level 15 includes Hippocampus [HC], in dorsal and ventral pathways. HC integrates fast responses and object perception. Processing is for memory.
Spinal nerve tracts {spinal cord}| organize basic movements, like running or walking, and control sense input. Spinal cord has inner gray matter cell bodies and outer white matter myelin, in lemnisci.
laminas
Lamina V is for pain and visceral afferents. Lamina VI is for joints and skin positions. Lamina VIII is medial motor neuron column for motor neurons to trunk and limbs. Lamina IX is lateral motor neuron column for motor neurons to arms and legs, with flexor central and extensor peripheral. Lamina X is central canal.
locations
Pain, heat, and cold axon tracts are on spinal-cord lateral sides. Touch and pressure axon tracts are on ventral side. Muscle-sensor axon tracts are on dorsal side.
Axons and dendrites can mix {neuropil}.
Spinal cord has outer white matter {lemnisci} with fascicles grouped into funiculi columns.
Spinal-cord outer white matter has descending and ascending axon tracts {fascicle} grouped into lemnisci.
Spinal-cord lamina I {Lissauer's tract} {Lissauer tract} is for pain.
Spinal-cord dorsal-horn lamina II {substantia gelatinosa} receives touch, pressure, pain, and thermal sensations.
Spinal-cord laminas {lamina III} can be for position and light touch.
Spinal-cord laminas {lamina IV} can be for position and light touch.
Spinal-cord laminas III and IV {nucleus proprius} are for position and light touch.
Spinal-cord laminas {lamina VII} {dorsal nucleus} {Clarke's column} can have intermediolateral nucleus and be for preganglion sympathetic system.
Spinal-cord lamina-VII dorsal nucleus ganglion {intermediolateral nucleus} contains preganglion sympathetic neurons.
Spinal-cord nerve tracts {medial longitudinal fasciculus} can be for head and eye coordination and come from vestibular nuclei.
Spinal-cord tracts {reticulospinal tract} can modulate sensation and spinal reflexes.
Spinal-cord tracts {rubrospinal tract} can be motor.
Spinal-cord back horn {dorsal horn} is for sense input and has ascending sense-connector nerves.
functions
Dorsal column is for fine touch and proprioception from skin, tendon, and joint.
layers
Dorsal horn has five layers. Layer 1 receives axons from skin neurons and sends to neurons higher in spinal cord. Layers 2 and 3 modulate sense input from both skin neurons and neurons in layers 4 and 5. Layer 4 receives axons from skin neurons and sends axons to layer 5. It detects gentle and general pressures. Layer 5 receives axons from skin, viscera, and layer-4 neurons and sends to brain.
nuclei
Neuron nuclei {dorsal column nuclei} receive afferent fibers from skin and send to ventrobasal complex.
tracts
Tracts are spinothalamic tract, dorsal spinocerebellar tract, ventral spinocerebellar tract, and spinoreticular pathway.
neurons
Nociceptive-specific neurons respond to noxious stimuli. Wide dynamic range neurons respond to all mechanical stimuli, but especially to noxious mechanical or thermal stimuli.
Spinal-cord front horn {ventral horn} is for motor output and has descending motor nerves. Tracts are lateral corticospinal tract, anterior corticospinal tract, vestibulospinal tract, rubrospinal tract, reticulospinal tract, and tectospinal tract. Descending autonomic neurons come from hypothalamus and brainstem. Medial longitudinal fasciculus is for head and eye coordination and comes from vestibular nuclei.
Voluntary escape behaviors use small efferent spinal cord fibers with long latencies and variable responses, which react to visual, tactile, and vibratory threats.
Spinal cord and brain have connective tissue layers {meninges}|, dura mater, pia mater, and arachnoid. Cerebrospinal fluid is between layers and in central canal.
Spinal cord has inner connective tissue layer {arachnoid}.
Spinal cord has outer connective tissue layer {dura mater}.
Spinal cord has middle connective tissue layer {pia mater}.
Cells {neuron} can have cell body, dendrites sending signals in, and axon carrying signals out.
shapes
Surroundings and connections cause unique neuron shapes. Large named neurons with special shapes include spinal cord anterior horn cells, cerebellum Purkinje cells, lateral vestibular Deiters cells, teleost Mauthner cells, primate cerebral cortex Betz cells, and primate cerebral cortex Meynert cells. Mauthner cells are for escape and startle reflexes.
size
Neurons are largest human cells, with average diameter 20 microns. Neuron volume is thousand times larger than bacterium volume.
firing rate
Neurons can output signals at maximum rate {rate saturation, neuron}, different for different neurons, up to 900 per second.
neuron genes
100 different neuron types express different gene sets. 80% of genes have repression, and the other 20% have expression at different levels, varying with cell conditions and transcriptional control. 20% of genes are for transcriptional control [Keller, 2000] [Stevens, 1998].
individuality
Neurons are different, because brains have hundreds of neurotransmitters and neurohormones, such as amino-acid derivatives, peptides, and small RNAs. Neurons have different membrane-receptor, membrane-polarization, myelination, microtubules, and gene-expression patterns. Neurons differ temporally, with different responses over different time scales. Interactions cause neurons to act differently [Grush and Churchland, 1995] [Shepherd, 1991].
One neuron {command neuron} can code for complex functions {single neuron doctrine}, because it responds to feature set [Calvin and Ojemann, 1994] [Kreiman et al., 2000] [Kreiman, 2001] [Kreiman et al., 2002] [Ojemann et al., 1998]. For example, after training, neurons can respond preferentially to face, hand, or object aspects.
problems
Number of brain neurons is not large enough to account for all possible objects and views. Neurons do not seem to converge on one brain area. Convergence is slow process, but pattern-representation formation is fast. Researchers have not found brain command neurons. Single cells cannot change efficiently in response to environment or body changes.
Dendrite proteins {cytoplasmic polyadenylation element binding protein} {CPEB protein} can bind to polyA regions, have active and inactive states, build other synapse proteins, and affect other protein shapes.
Neuron extracellular-potential changes have minor electrical effects {ephaptic interaction} on other neurons [Holt and Koch, 1999].
Neuron output depends on product of various inputs {gain field}. Outputs combine neuron population codes.
Neuron can output continuously variable electrical potential {graded potential} rather than impulse.
A microelectrode {neuronography} can stimulate one nerve.
Neurons have reflexes, ON-center neurons, other neuron types, ganglia, orientation columns, topographic maps, association cortex, and memory systems {neuron assembly}.
reflexes
Brain can modify reflexes. Inhibition from controllers and excitation from motivators compete to cause behavior or fading.
ON-center and OFF-center neurons
ON-center and OFF-center neurons detect points and lines. ON-center and OFF-center neuron arrays can detect point and line arrays and so textures, boundaries, and objects.
neuron types
Besides ON-center neurons, other neuron types detect color and other intensities.
orientation columns
Cortical orientation columns detect line and boundary orientations and detect angles and so detect surface orientations.
topographic maps
Ganglia and topographic maps code relations among perceptions and motions.
association cortex
Association cortex controls series and parallel perceptual and motor systems, integrating information to guide behavior.
memory systems
Cortical systems have three-dimensional registers to hold spatial perceptual information temporarily and permanently.
The main fiber {axon}| from soma is thin and smooth cylinder with neurofilaments. It is conductive. It has same-size branches at obtuse angles. It has bulbous endings and/or calyciform endings. It has small varicosities in chains. It has no ribosomes. It attracts specific dendrites.
Chemical flow in both directions supplies axon ends with molecules from cell body.
number
Most neurons have one axon. Retinal amacrine and olfactory granule cells have no axons. Dorsal root ganglion cells have multiple axons and no dendrites. Dorsal root ganglion cells have axon that bifurcates. Invertebrate cells often have one axon, with dendrites from it.
microtubule
Only axon hillock and initial segment have microtubule fascicles, have membrane undercoating, and have high sodium-channel density.
excitation or inhibition
Axon terminals are either all excitatory or all inhibitory.
regeneration
Axons can regenerate, if allowed by surrounding glial cells.
Axon initial segment {trigger zone} {axon hillock}| has many sodium channels and allows action potential to trigger.
If axon disrupts, Nissl substance changes appearance {chromatolysis} over 4 to 12 weeks.
Microtubules and neurofilaments {cytoskeleton} make cell and axon framework.
Wide filament protrusions {dendrite}| from soma have synapses for axons.
anatomy
Dendrites have microtubules. Dendrites do not myelinate or have one myelin layer.
shape
Branching dendrites provide maximal surface area for receiving input from other neurons. Larger diameter and/or shorter length make larger effects on initial segment.
Proximal and distal dendrites are different.
Widespread dendrites receive from many sources. Compact dendrites receive from one source.
Dendrites can radiate straight out in all directions with few spines, as in large ventral-horn motor cells and reticular-formation cells. They can branch with spines curving in one direction, as in cerebral-cortex pyramidal cells and secondary sense nuclei. They can have special patterns and locations. Cerebellar Purkinje cells are planar semicircles. Inferior-olive clustered cells are curved and wavy. Ventral-cochlear nucleus cells are tufted. Smaller branches are at acute angles and have thorns.
Dendrite patterns match incoming axon patterns. Branches orient along body axes, brain surfaces, and nerve bundles.
Dendrites can change shape over days.
main
Cell body typically has several dendrite origins {basal dendrite}. Cerebellar Purkinje cells have one dendrite trunk {apical dendrite}. Dorsal-root ganglion cells have no dendrites. Invertebrate cells often have one axon, with dendrites from it.
properties
Dendrites have high resistance and capacitance. At dendrite ends, membrane is relatively unexcitable.
If stereotyped behavior happens over four to five months, dendrites from several antagonistic motor neurons make a bundle {dendritic bundle}.
Dendritic protrusions {dendritic spine} have asymmetric synapses. Spines vary in shape, size, and density, even on one dendrite. They can change shape over days. One dendritic spine has only one Type 1 synapse but can also have one Type 2 synapse. Spines have alpha-tubulin, beta-tubulin, actin, and myosin filaments. They have endoplasmic reticulum. Excitation is at spine tips. Inhibition is at dendritic bases or on cell surface. More spines indicate more excitation.
All animals have synapses {electrical synapse} {gap junction, synapse} that use ion flows in one direction and are excitatory or inhibitory [Beierlein et al., 2000] [Blatow, 2003] [Gibson et al., 1999].
function
Electrical synapses make adjacent cells fire at same time. Cortex interneuron groups link by electrical synapses and can act together to inhibit.
comparison
Electrical synapses are faster but less efficient than chemical synapses, with signal one-quarter original signal. For example, if presynaptic membrane is 100 mV, post-synaptic membrane is 25 mV.
properties
Electrical synapses cannot have facilitation and do not change shape.
Sodium, potassium, calcium, and chloride have passageway {ion channel, neuron}| through membrane protein. Ion channel for receptor potential differs from ion channel for action potential [Doyle et al., 1998] [Heinemann et al., 1992] [Hille, 2001].
Synapses {Malsburg synapse} {von der Malsburg synapse} can rapidly control connectivity between cells, allowing transient cell assemblies.
Lipids {myelin}| can increase axon conduction rates and separate nerve fibers. Schwann cells in PNS, and oligodendrocytes in CNS, make myelin. Schwann cells measure neuregulin in axons and make more myelin if it is higher and less if it is lower. Myelination begins in brain lower back after birth and moves toward frontal lobes, finishing about age 25. Myelin can have up to 150 layers. Conduction is fastest when axon diameter to total diameter is 0.6.
Neuron membrane sites {neuroreceptor} bind molecules.
types
Neuroreceptors include alpha-adrenergic catecholamine such as alpha2-adreneric, AMPA, angiotensin, beta-adrenergic catecholamine, D1, D2, GABA, glycine, kainate, M, metabotropic, muscarinic ACh, N, and NMDA receptors.
hormone
Hormone binds to cell-membrane outer-surface neuroreceptor protein, which opens membrane channel for up to one second. On cell-membrane inner surface, neuroreceptor protein couples to G protein and activates adenylate cyclase, guanylate cyclase, phospholipase c, or phosphoinositidase C, which produces soluble cAMP, cGMP, or phosphoinositide second messenger, which diffuses into neuronal cytoplasm and changes local membrane potential.
Cyclic nucleotide or phosphoinositide can either stimulate or inhibit other enzymes. ADP triphosphoinositide {phosphatidylinositol 4,5 diphosphate} hydrolyzes to release water-soluble inositol triphosphate (IP3) (ITP), which releases calcium ion from intracellular storage, which initiates enzyme phosphorylation. Phosphoinositidase C hydrolysis makes diglyceride containing arachidonic acid, which, with calcium and phospholipid, activates protein kinase C.
neurotransmitter
A 10-nanometer-wide glycoprotein channel spans cell membrane and activates by neurotransmitter. Activation allows ions to flow through channel down concentration gradient. Sodium ions flow from outside to inside membranes. Potassium ions flow from inside to outside membranes. Chloride ions flow from outside to inside membranes. Channel opens for only one microsecond, because neurotransmitter rapidly dissociates or inactivates.
Ribosome clumps {Nissl body}| {Nissl substance} are in rough endoplasmic reticulum cisterns. If axon disrupts, Nissl substance changes appearance {chromatolysis, Nissl substance} over 4 to 12 weeks.
Points {Ranvier node} {node of Ranvier}| along myelinated axon have no myelin. Conduction jumps from node to node. Beside node, which has sodium channels, is paranode, which has juxtaparanode, which has potassium channels, beside it.
Neurons have cell bodies {soma} {perikaryon}.
Protein discs {postsynaptic density} (PSD) are on presynaptic and postsynaptic chemical-synapse membranes. PSDs have beta-adrenergic, glutamate, and gamma-aminobutyric acid (GABA) receptors. They have protein kinase enzymes that phosphorylate to alter synaptic structure. They contain filamentous proteins that can move and change shape, such as actin, actin/calmodulin-binding protein, fodrin or brain spectrin, and tubulin. Fodrin or brain spectrin is an actin-binding and calmodulin-binding protein.
Axon terminal synapses have hexagonal grids {presynaptic grid}, with six particles surrounding each vesicle.
Cell enzyme produces soluble cyclic nucleotide, cAMP or cGMP, or phosphoinositide {second messenger}|, which diffuses into neuronal cytoplasm and changes local membrane potential.
Axons connect to dendrites at chemical sites {synapse}|. Neuron activity, habituation, and sensitization affect synapses. With more activity, number of synapses per neuron increases, synapse density per unit volume rises, and dendrite length increases. Neuroactive compounds exert influence up to 20 nanometers within synaptic cleft or up to 2 millimeters from varicosities or unstructured release points [Gray, 1977].
In synapses, space {synaptic cleft}| between membranes is 20 nm wide and has acidic and basic glycoproteins and mucopolysaccharides, with dense line in middle, that bind membranes. Synaptic cleft is bigger in asymmetric synapses.
Cortical axons have ending arrays {arborization} {synaptic terminal}| with total diameter 0.5 millimeters, containing 2000 boutons and synapses.
Presynaptic areas have membrane sacs {synaptic vesicle}| {vesicle} with neurotransmitter molecules. Vesicles contain only one transmitter type.
types
Clear synaptic vesicles contain acetylcholine, glycine, GABA, glutamate, aspartate, or neurohormones. Vesicles with granule in middle contain dopamine, noradrenaline, adrenaline, or serotonin. Larger granular vesicles contain peptides.
transmitters
Adrenal chromaffin cells store opiate peptides and catecholamines. Sympathetic neurons and neuromuscular junctions store ATP and other transmitters. Hypothalamic magnocellular neurons store vasopressin and oxytocin. Autonomic neurons store acetylcholine and VIP or norepinephrine Y.
biology
One spike releases one packet. Vesicle containing acetylcholine has 1000 to 10,000 molecules. Vesicles contact cell membrane, because time is less than 200 microseconds between first calcium entry and first neurotransmitter in synapse.
Excitatory synapses {asymmetric synapse} {Type 1 synapse} can have postsynaptic density, round vesicles, and wide clefts and connect mainly to dendritic spines.
Inhibitory synapses {symmetric synapse} {Type 2 synapse} can have small and narrow synaptic clefts, ellipsoidal or flattened vesicles, and no postsynaptic density and connect mainly to dendritic shafts and cell bodies.
Neuron axons can have long chains of swellings {varicosity}, which are similar to synapses and release neurotransmitter from their surfaces near dendrite terminal branching regions.
Neurons attach {neuron adhesion} {neural attachment} symmetrically at zonula adhaerens, punctum adhaerens, zonula occludens, and nexus. Neurons have no macula adhaerens or desmosome.
Neurons adhesions {punctum adhaerens} attach symmetrically.
Neurons attach symmetrically at chemical synapses {zonula adhaerens}.
Neurons attach symmetrically between epithelial or endothelial cells {zonula occludens} {tight junction}.
Neurons make electrotonic synapses {nexus, synapse}.
Electrotonic synapses have membrane proteins {connexon} for ion transmission.
Neurons have physiology {neuron, physiology}.
signals: initiation
Neurotransmitter reception reduces membrane voltage. Membrane voltage reduction spreads. At axon hillock, membrane voltage can reach threshold voltage, causing depolarization spike, which initiates depolarization-spike traveling wave down axon.
Perhaps, only one dendrite-and-cell-body membrane potential distribution can cause initiation. Only one distribution can reach threshold potential. One distribution has much higher probability than others, because it can happen in the most ways. Dendrite and cell body changes can change distribution. Perhaps, neuron groups also detect only one input distribution.
signals: firing rate
Neuron input to neuron-firing rate ratio is linear or S-shaped.
conduction rate
Non-myelinated-axon conduction rate is between 0.5 and 2 meters per second, 1 millimeter per millisecond. Myelinated-fiber conduction rate is between 2 and 120 meters per second, 10 millimeters per millisecond, and is faster because signals jump from one Ranvier node to the next {saltatory conduction, myelin}.
Conduction rate in axons varies irregularly.
Faster impulse conduction became necessary as animals became larger.
conduction rate: synapse
Conduction rate across synapse is one micrometer per millisecond. Irregular synapse sizes and neurotransmitter-packet release times vary conduction rate.
Post-synaptic decay takes up to ten milliseconds.
conduction rate: synchronization
Information-flow rates along axons, synapses, and receptors change typically do not synchronize with rates on other axons, synapses, and receptors.
neuron growth
Neurons grow, differentiate, migrate, and extend axons and dendrites, at different rates. Extracellular substances, cell-membrane molecules, and cell and axon spatial arrangements affect growing axons. Cell-membrane-molecule and extracellular-substance gradients change over time. Target neurons grow and mature in coordination with axon growth.
neuron growth: direction
Adhesion-glycoprotein neurotrophins guide growing nerve processes to appropriate target neurons.
neuron growth: process
First, several axons travel over relatively short distance. After axons stop extending, they produce multiple branches, which form many connections. Branch retraction and synapse reduction then reduce connections. First nerve impulses, which are possibly synchronous, refine axon connections [Thompson, 1940] [Wolpert, 1977].
nutrition
Nerve cells need glucose and oxygen, because they have no substitute biochemical pathways.
plasticity
Neuron number, spatial arrangements, diameters, composition, lengths, types, controllers, molecules, membranes, axons, dendrites, cell bodies, receptors, channels, synapses, threshold voltages, and packet number can change. Receptor number, type, effectiveness, and position can change.
plasticity: repair
After brain damage, nearby axons invade damaged region to make new circuits, and axons try to contact nearby dendrites.
Unconditioned stimulus (UCS) releases serotonin from axon to axon synapses {axoaxonic synapse}, which increase protein kinase A, which releases more glutamate. Association is non-Hebbian.
Cutting axons {axon cutting} makes neuron die and nearby axons sprout processes to innervate neuron dendrites that used to contact dead neuron.
Proteins, lipids, and neurotransmitters travel 300 mm/day {axon transport}|, away from cell soma. Mitochondria travel 75 mm/day, away from cell soma. Actin microfilaments, glycolytic enzymes, myosin-related polypeptides, calmodulin, and clathrin travel 5 mm/day, away from cell soma. Microtubules and neurofilaments travel 1 mm/day, away from cell soma. Lysozyme breakdown products travel 250 mm/day, back to cell soma. Fast transport uses ATP and kinesin protein along microtubules.
Depolarization increases glutamate binding to NMDA receptor, which activates pathways {CREB pathway} to increase cyclic AMP, which increases CREB protein, which increases transcription of genes that make synapses larger and more efficient.
Neurotransmitter packets reaching post-synaptic cell-membrane neuron receptors cause small voltage differences, positive {excitation} {hyperpolarization} or negative {inhibition} {depolarization}|. Sodium ions diffuse into cell, and potassium ions diffuse out, causing voltage change across cell membrane. Voltage change spreads to nearby cell membrane.
Depolarization increases glutamate binding to NMDA receptor, which activates CREB pathway to increase cyclic AMP, which increases CREB protein, which increases transcription of genes that make synapses larger and more efficient.
In sympathetic autonomic ganglia, presynaptic cholinergic fibers excite one neuron class with acetylcholine and another class with LHRH-like peptide, which diffuses several micrometers to make slow excitatory postsynaptic potential {excitatory postsynaptic potential} (EPSP).
Neuron-axon back projections can cause long-term membrane depolarization {facilitation}|.
Most reflex responses decrease {habituation}| if non-threatening stimulus repeats without reinforcement. Receiving same stimulus repeatedly or continuously decreases sensation.
purpose
Habituation allows animal to ignore persisting situation or disregard irrelevant stimuli.
specific
Habituation is only to specific stimulus. Habituation ends immediately when stimulus pattern changes. Therefore, dishabituation can detect if animal perceives anything new.
behavior
Sexual behavior can have habituation.
timing
Habituation happens sooner the second time. Habituation happens sooner to weak stimuli.
time
In mammals, habituation decreases receiving-neuron post-synaptic potential for up to one hour. Because back-projection signals decrease, calcium influx is lower, sending neuron releases less transmitter, and receptor alters.
In marine snails, decreased vesicle release, from sense to motor neurons, causes habituation that persists for minutes. Repeated habituation decreases presynaptic-terminal number.
comparison
Tiredness does not cause habituation. Habituation cannot be for associative learning.
Senses have absolute intensity differences {just noticeable difference}| (JND) {difference threshold}, between two stimuli, that people can perceive. Stimulus intensity ratio typically ranges from one to three but can be up to sixty.
For fast millisecond effects, neurotransmitter receptors have ion channels {ligand-gated ion channel}. Fast neurotransmitters include acetylcholine and glutamate.
If climbing fiber depolarizes Purkinje cell, parallel fibers make nitrogen oxide, which increases cGMP in Purkinje cell, which activates protein kinase G, which makes receptors less sensitive {long-term depression} (LTD).
Dendrite spine synapses can have long-lasting changes {long-term potentiation} (LTP).
process
Presynaptic glutamate release activates N-methyl-D-aspartate (NMDA) postsynaptic receptors, causing Ca++ entry into postsynaptic neurons, which activates calcium/calmodulin protein kinase II (CaM kinase II), protein kinase C, and/or tyrosine kinase, which changes spine shape, synapse shape, or receptors. Perhaps, CaM kinase II adds AMPA receptors to postsynaptic membrane. Spine shape alteration exposes NMDA receptors and changes spine electrical properties. Short spine neck has high electrical resistance that amplifies depolarization. Lengthening neck permits increased Ca++ influx.
time
High-frequency hippocampus or cortex nerve stimulation increases synapse depolarization for hours {early LTP}, and, if repeated, up to weeks {late LTP}.
purposes
LTP aids space representation and affects spatial memory.
protein
Cell-membrane binding integrin protein maintains long-term potentiation and so aids memory.
locations
In hippocampus, Schaffer collateral pathway, from hippocampus region CA3 pyramidal cells to hippocampus region CA1, uses glutamate, is associative, and has post-synaptic NMDA receptor modulation. Hippocampus region CA3 pyramidal cells receive from dentate gyrus. Mossy fiber pathway, from dentate gyrus granule cells to hippocampus region CA3, uses glutamate, is non-associative, has norepinephrine interneuron modulation, and seems not to affect declarative memory. Dentate-gyrus granule cells receive from entorhinal cortex.
Regular low-frequency stimulation causes presynaptic bulb hypopolarization {low-frequency depression} (LFD) and decreases post-synaptic neuron output.
Acetylcholine can bind to slow neurotransmitter receptors {muscarinic ACh receptor}.
Adult bird, primate, and human brain neural stem cells divide to form neural precursors and new neural stem cells {neurogenesis}. Neurogenesis increases with brain activity.
Drugs, learning, growth, disease, accident, mutation, hormones, and chance can alter neuron properties {plasticity}|. Brains can change structure in response to stimuli and so learn [Petit and Ivy, 1988] [Robertson, 2000].
After binding a neurotransmitter packet of 1000 to 10,000 molecules, post-synaptic membrane changes 1 mV to 15 mV {post-synaptic potential} (PSP), with average of 10 mV, lasting 10 to 100 milliseconds. Initial change is rapid, and decay is slow. Potential change affects membrane up to two millimeters away. Spontaneous neurotransmitter release makes changes of 0.5 mV, lasting 20 milliseconds. Miniature end plate potentials depolarize synapse by 0.7 mV, lasting 10 milliseconds. Frequency is directly proportional to membrane depolarization. Frequency is five per second at membrane resting voltage.
Regular high-frequency stimulation causes presynaptic bulb hyperpolarization {post-tetanic potentiation} (PTP) and increases post-synaptic neuron output.
All cells in all organisms have receptor potentials and action potentials {potential gradient}, caused by sodium-ion, potassium-ion, and chloride-ion concentration gradients across cell membranes. All cells have potential changes, as ions move through membrane channels. Neurons require energy to maintain ion balance across membranes.
In excitatory axons, conditioned stimulus (CS) allows calcium to enter axon terminal and release glutamate {presynaptic facilitation}. Unconditioned stimulus (UCS) releases serotonin from axon-to-axon axoaxonic synapses, which increase protein kinase A, which releases more glutamate. Association is non-Hebbian. More UCS also activates MAP kinase and expresses genes to make more glutamate synapses.
In excitatory axons, unconditioned stimulus inhibits presynaptic bulb {presynaptic inhibition}.
Brain activity leaves trace {priming, nerve}, making path more easily excitable next time. Priming lasts tens to hundreds of milliseconds. Priming sets or sequences {context, priming} last minutes or hours.
Conscious states last 100 to 150 milliseconds {psychological refractory period}, same time it takes to make or perform decisions. Perhaps, after sending feedforward signal, brain sends no more signals for refractory period, to allow time to check first-signal results.
Inactive periods {refractory period, neuron}|, 0.75 milliseconds to 4 milliseconds, follow neuron spikes at axon positions, as membrane returns to normal voltage.
Receptor size and information processing method determine smallest size {resolution} that sense can detect. For example, eye can see 1 arc-second or 0.000001 meter, microwave size. Wavelengths longer than microwaves are not good for vision because spatial resolution is poor.
In myelinated fibers, conduction rate is between 2 and 120 meters per second or 10 millimeters per millisecond, as signal jumps {saltatory conduction, myelinated fiber}| from one Ranvier node to the next. Conduction rate along all axons varies irregularly.
Neurotransmitter binding to synapse receptors reduces membrane voltage, which spreads to axon hillock. When membrane voltage reaches threshold at axon hillock, cell membrane has large and rapid voltage change {spike, axon}| [Koch, 1999] [Salinas and Sejnowski, 2001] [Softky, 1995].
level
Spike voltage rises from -70 mV to +5 mV in 0.5 millisecond and then falls back to -70 mV in 0.5 millisecond.
time
Depolarizations have short duration, allowing precise time and time-interval coordination and comparison.
strength
Depolarizations have same strengths and time intervals. Depolarization prevents nerve-signal deterioration with distance and time, allowing axons to be long and act over long time intervals. Neurons can thus be anywhere and have any pattern.
threshold
Threshold can vary, between -50 mV and -30 mV.
Depolarization makes neurons act like switches. Threshold keeps neurons off until they switch on. Rapid recovery makes them switch off.
Computers are switching networks and can change switch thresholds.
Switches can contain messages in binary code [Adrian, 1980].
travel
Depolarization brings adjacent cell membrane to threshold, causing adjacent spike. That spike, in turn, causes adjacent cell membrane to reach threshold, causing adjacent spike. Spikes travel along axon from axon hillock to synapse.
direction
Spikes cannot go backward because cell membrane takes time to recover from spike. Ions at previous-spike cell membrane have low concentration and do not flow across membrane.
rate
Axons can sustain up to 800 spikes per second. Spikes cannot repeat faster at a cell-membrane location, because cell membrane takes 0.5-millisecond refractory period to recover from a spike.
factors
Axon hillocks do not distinguish neurotransmitters, receptors, or input patterns. All things that effect membrane voltage merely add.
Neurotransmitter synapse effects can be fast and short or slow and long {synaptic transmission}.
For fast millisecond effects, neurotransmitters, such as acetylcholine and glutamate, bind to receptors with ligand-gated ion channels.
For slow 0.1-second to 10-second effects, neurohormones, such as dopamine, acetylcholine, and neuropeptides, bind to receptor that activates GTP-binding proteins {G-protein}, which make second messengers such as cyclic AMP, diacylglycerol (DAG), or inositol triphosphate (IP3), which phosphorylate.
Stimuli can cause neuron sets to fire simultaneously {synchronization}, 40 to 100 milliseconds after stimulus. Neurons with overlapping same-type receptive fields have the most synchrony. Synchronous neuron activity is always in phase, not in opposite phase. Synchronous neuron signals do not encode information about space, objects, or time.
High-frequency electrical stimulation causes maximum nerve signaling {tetanus, nerve}|.
Cell membrane has voltage {threshold, neuron} at which it starts depolarization spike. Low threshold allows too much noise. High threshold cuts off boundary effects, shading, and small differences.
absolute
Senses have smallest detectable stimulus {absolute threshold}, which people can sense 50% of time. For vision, humans can detect light if seven photons flash in absolute darkness. For hearing, humans can detect whisper at five meters in absolute silence. For touch, humans can detect small insect wing or foot in still air. For smell, if small perfume drop is in ballroom, air is still, and no other odors are present, humans can detect perfume. For taste, humans can detect four grams of sugar in one liter of water.
Presynaptic cholinergic neurons excite peripheral sympathetic neurons {trans-synaptic enzyme induction}.
Neuron and glia molecules cause nerve growth {trophism}|, guide axon tips to final locations during development, regulate and maintain nervous-system connections, and stimulate neurotransmitters.
At receptor, catecholamine agonist causes desensitization {tolerance, regulation}, because agonist receptors have reduced affinity and subsequently decrease in number {down-regulation}. Down-regulation persists for days after transmitter concentrations have returned to normal {temporal amplification, down-regulation}.
Denervation, catecholamine depletion, or catecholamine antagonist treatment causes suprasensitivity {up-regulation}, because receptor number increases. Up-regulation persists for days after transmitter concentrations have returned to normal {temporal amplification, up-regulation}.
Motor neurons {alpha motor neuron} can initiate movement by stimulating muscles.
Brain has many small nerve cells {amacrine cell, neuron} {microneuron}, which inhibit other neurons in memory and other processes. Amacrine cells have 27 types and send to the ten inner-plexiform layers.
Cerebellum neurons {basket cell} can receive excitation from parallel fibers and laterally inhibit adjacent-column Purkinje cells. Axons go one millimeter away and form multiple synapses on cell bodies and dendrites. Basket cells make GABA for inhibition.
Brain has elongated neurons {bipolar cell, neuron} of 10 types that send to the ten inner plexiform layers.
Medial entorhinal cortex and para-subiculum have 10% cells {border cell} that fire when viewing a nearby border.
Brain neurons {chandelier cell} can inhibit pyramidal cells with multiple synapses at axon base. Chandelier cells make GABA for inhibition.
Basal nucleus of Meynert, medial septal nucleus, and brainstem nuclei neurons {cholinergic neuron} can make acetylcholine and alter in Alzheimer's disease, ALS, and spinal cord injury.
Visual-cortex cells {complex cell} can receive from simple cells and ganglion cells. Complex cells have ocular dominance or orientation tuning.
functions
They can detect stereoscopic effects, such as line-segment ends, colors, motions, and line orientations. They can mark region boundaries, such as regions with same reflectance. They discriminate and aggregate. They can detect patterns, at any location.
fields
Complex cells have different receptive-field sizes and detect different spatial frequencies and so widths. Sets can detect 8 to 30 different frequency bands and spatial scales, using spatial frequency channels, from pixel, spot, region, quadrant, or whole visual field.
time
Complex-cell sets can operate at 10 to 30 different temporal scales, from milliseconds to years.
Edge neurons {double-bouquet cell} can make GABA to inhibit other-edge-side vertical-column activity.
Simple cells can detect line or bar ends {end-stopped inhibition} {end stopping, simple cell} or detect no end. End-stopping cells increase firing rate, as bar length increases up to maximum, and then decrease firing rate, as bar gets longer.
Neurons {excitatory neuron} can excite other neurons.
types
They are either bursting {bursting cell} or non-bursting. They cannot change from one type to the other.
bursting
Bursting cells respond to sustained intracellular current with two to four spikes, followed by hyperpolarization, followed by burst, followed by hyperpolarization, and so on, with 0.2 to 10 cycles per second.
Bursting cells are large. Apical dendrites extend to layer 1 to contact many cells. Axons project to ipsilateral superior colliculus.
Bursting neurons accumulate calcium more efficiently in axon terminals than cells that have isolated spikes.
Layer-5 bursting neurons induce synaptic plasticity in neurons outside cortex. Spike bursts turn on short-term memory, which then decays over several seconds.
non-bursting
Non-bursting neurons, such as pyramidal or spiny stellate neurons, have one spike or sustained output. They do not have spike cycles.
Interneurons {GABA neuron} {GABA+ neuron} can have no dendrite spines {smooth neuron, GABA}. They affect epilepsy and Huntington's disease [Koch, 1999] [Lytton and Sejnowski, 1991] [McBain and Fisahn, 2001].
Motor neurons {gamma motor neuron} can control muscle length/tension relationships, by exciting nearby alpha motor neurons and stimulating muscle sensors.
Retinal output neurons {retinal ganglion cell} {ganglion cell, retina output}| generate action potentials and have axons in optic tract to brain [Enroth-Cugell and Robson, 1984] [Meister, 1996] [Niremberg et al., 2001] [Warland et al., 1997].
biology: types
Ganglion cells are magnocellular M, parvocellular P, and mixed W, which process signals separately and send separate information streams to lateral geniculate nucleus (LGN).
Retinal ganglion cells {X-cell} {beta retinal ganglion cell} can sum linearly across receptive fields. X cells have large dendritic fields. X-cells resolve finer visual patterns with higher spatial frequencies. X cells make tonic and sustained signals, with slow conduction, for detecting details and spatial orientation. More X cells are in fovea. X cell axons go to simple cells.
Magnocellular cells respond better to motion, respond better to transient stimulation, respond better to small intensity differences, are larger, have larger receptive fields, have thicker axon with faster signals, have firing rate that plateaus only at high intensity, and signal scene changes.
Retinal ganglion cells {Y-cell} {alpha retinal ganglion cell} can sum non-linearly. Y cells have small dendritic fields. Y-cells are larger and have thicker and faster conducting axons. Y cells make phasic and transient signals, with fast conduction, for stimulus size and temporal motion. More Y cells are in periphery. Y cell axons go to complex cells.
Parvocellular cells have several types, have better spatial resolution, detect color, detect higher contrast, detect more detail, are more numerous, and have more linear responses.
Both X-cells and Y-cells have ON-center and OFF-center neurons. X-cells and Y-cells have different receptive field sizes, stimulus velocity sensitivities, and spatial frequencies.
Retinal ganglion cells {W cell} can be small and direction sensitive, with slow conduction speed. W cells mix M and P cell properties and are rarest.
biology: neuron shapes
Ganglion cells {bistratified neuron} {small bistratified neuron} can have two dendrite layers. Cells {shrub neuron} can have dendrite bushes.
Ganglion cells look like auditory nerve cells, Purkinje cells, olfactory bulb cells, olfactory cortex cells, and hippocampal cells.
biology: input
Small central-retina midget ganglion cells have small dendrite clump, to collect signals from one midget bipolar cell. Midget cells respond mostly to contrast.
Parasol ganglion cells can receive from diffuse bipolar cells with bigger dendrite trees and can have dendrite umbrella, to collect signals from wide area. Parasol cells respond mostly to change.
biology: output
Ganglion cells send to LGN and then to cortical hypercolumn.
functions
Visual-receptor cells take illumination logarithm and hyperpolarize 0 mV to 4 mV from resting level 10 mV to 30 mV [Dowling, 1987] [Enroth-Cugell and Robson, 1984] [Wandell, 1995]. Retinal ganglion cells sum bipolar, horizontal, and amacrine retinal-neuron activities. Retinal ganglion cells have low spontaneous-firing rate. Ganglion cells typically respond quickly and then turn off.
Retinal ganglion cells make action potential after cyclic GMP reduces, decreasing sodium conductance through cell membrane.
functions: spots
Retinal ON-center ganglion cells can respond when light intensity above background level falls on center of their receptive field. See Figure 1. Light falling on annulus surrounding receptive-field center inhibits cell.
When light smaller than center falls on center, ON-center neuron fires rapidly and then slowly. After removing light, ON-center neuron continues low firing rate. When light smaller than annulus falls on annulus, ON-center neuron does not fire. After removing light, ON-center neuron fires rapidly and then slowly.
ON-center neurons have four types, depending on excitation and inhibition. One has high firing rate at onset and zero rate at offset. One has high rate, then zero, then high, and then zero. One has high rate at onset, goes to zero, and then rises to constant level. One has high rate at onset and then goes to zero.
Other ganglion cells {OFF-center neuron} respond when light intensity below background level falls on receptive-field center. OFF-center neurons increase output when light intensity decreases in receptive-field center. Light falling on annulus around receptive-field center excites OFF-center cells.
When light smaller than center falls on center, OFF-center neuron does not fire. After removing light, OFF-center neuron fires rapidly and then slowly. When light smaller than annulus falls on annulus, OFF-center neuron fires rapidly and then slowly. After removing light, OFF-center neuron continues low firing rate.
Bipolar cells excite ON-center and OFF-center neurons. ON-center and OFF-center neurons compare light intensity falling on receptive-field center with that falling on annulus.
functions: bars
Band, bar, stripe, grating, or edge excites ON-center neuron in different ways.
If grating has wide stripes, ON-center neuron has only spontaneous firing, because one bright band affects both center and surround, exciting and inhibiting. See Figure 2.
If grating has narrow stripes, ON-center neuron has only spontaneous firing, because several bright bands affect both center and surround, exciting and inhibiting. See Figure 3.
If grating-stripe width lands on center exactly, ON-center neuron fires rapidly and then slowly. See Figure 4.
For wide single long bar, ON-center neuron has only spontaneous firing, because bright band affects both center and surround. See Figure 2.
For narrow single long bar, ON-center neuron has some firing, because bright band affects mainly center but is small. See Figure 5.
If long bar lands exactly on center, ON-center neuron fires rapidly and then slowly. See Figure 4.
For long bar with end beyond center, ON-center neuron has only spontaneous firing, because bright band affects both center and surround. See Figure 5.
For short bar with end not yet at center, ON-center neuron has only spontaneous firing, because bright band does not reach center. See Figure 6.
For bar with end on center {end stopping, neuron}, ON-center neuron fires rapidly and then slowly. See Figure 7.
For bright edge over center, ON-center neuron fires rapidly and then slowly. See Figure 8.
For bright edge not yet at center, ON-center neuron has no firing. See Figure 9.
For bright edge at middle, ON-center neuron fires some. See Figure 10.
If grating-stripe width lands on center exactly, ON-center neuron fires rapidly and then slowly. See Figure 4.
If grating-stripe width shifts to half on and half off, ON-center neuron fires some. See Figure 10.
If grating-stripe width shifts to all off, ON-center neuron does not fire. See Figure 9.
For bright or dim regions, ON-center neurons have only spontaneous firing, because bright light affects both center and surround.
For bright or dim regions, OFF-center neurons have only spontaneous firing, because bright light affects both center and surround. Relative brightness depends on lateral-inhibition patterns.
functions: movement
Ganglion cells {ON-OFF-center neuron} can detect movement. ON-OFF-center neurons use time derivative of ON-center neurons to find general direction and position. Amacrine cells also excite transient ON-OFF-center neurons.
functions: color
Retinal ganglion cells can be cone-shaped cells for color detection. The three types compare light intensities in frequency range. Type is for brightness, adds green and yellow-green, and has both on-center and off-center neurons. Another type has center for one cone color and surround for another color, to compare colors. Third type, with no surround, adds green and yellow-green for excitation and subtracts blue for inhibition, to compare blue to yellow.
Cerebellum has clusters {glomerulus, cerebellum} {glomeruli, cerebellum} of 20 granule cells.
Cerebellum neurons {Golgi cell} can be in granule-cell layer. Golgi cells receive input from parallel, mossy, and climbing fibers. They inhibit granule cells to provide feedback and feedforward inhibition. They change parallel fiber activity into brief burst.
Neurons {Golgi type I neuron} {local circuit neuron} can send locally with unmyelinated axons.
Neurons {Golgi type II neuron} {projection neuron} can send to other areas with myelinated axons.
Golgi cells inhibit cerebellum neurons {granule cell}. One mossy fiber excites 20-granule-cell clusters {glomerulus, granule cell} {glomeruli, granule cell}.
Medial entorhinal cortex has some cells {grid cell} that fire when body is at many spatial locations, which form a triangular grid [Sargolini et al., 2006].
Post-subiculum, retrosplenial cortex, anterior thalamic nuclei, lateral dorsal thalamic nuclei, lateral mammillary nucleus, dorsal tegmental nucleus, striatum, and entorhinal cortex have some neurons {head direction cell}, which receive from vision and vestibular systems, that fire only when head has an orientation in space [Sargolini et al., 2006].
Superficial pyramidal cells {hypercomplex cell} can detect corners, depths, and lengths.
Neurons {inhibitory neuron}| that inhibit other neurons fire faster than excitatory neurons, have few spines on dendrites {smooth neuron, inhibition}, and synapse directly on dendrites, cell bodies, or dendritic stumps, closer to axon hillock than excitatory axons. Inhibitory axons connect horizontally, only up to 100 to 200 microns away, except for basket cells.
Large spindle-shaped neurons {spindle neuron} {Korkzieher cell} are only in great-ape anterior-cingulate and frontal-area-FI lower layer 5, for output to other regions [Economo and Koskinas, 1925] [Nimchinsky et al., 1999]. Humans have them in much higher densities than other apes. They form after birth. Spindle neurons are for attention and self-reflection. Layer 6 has small spindle-like cells.
People have three million nerves {motor nerve} {motor neuron} to muscles and glands. Alpha motor neurons can initiate movement by stimulating muscles. Gamma motor neurons can control muscle length/tension relationships by exciting nearby alpha motor neurons and stimulating muscle sensors. Internuncial neurons can allow reciprocal inhibition.
input
Cerebrum, basal ganglia, brainstem, and cerebellum act on motor neurons. Impulse excitatory effect on motor neuron lasts 5 milliseconds.
regeneration
Motor nerves can regenerate connections to muscles.
Brain neurons {multipotent neural stem cell} can divide regularly to make neural stem cells and neural precursors. Half of neural precursors migrate, then mature into neurons or glia. Migration and maturation take one month.
Neurons {neural stem cell} can make five neuron types: TH+ neurons, GABA+ neurons, cholinergic neurons, astrocytes, and oligodendrocytes. Neural stem cells are mainly in ventricles and hippocampus. They can migrate to hippocampus and olfactory bulbs.
Excitatory neurons {pyramidal cell}| can connect one cortical area to another and fire in bursts. Pyramidal cells are both superficial and deep [Elston, 2000] [Elston and Rosa, 1997] [Elston and Rosa, 1998] [Elston et al., 1999].
functions
Pyramidal cells detect fast moving stimuli, such as moving edge at one orientation.
output
Cerebral cortex layer-5 pyramidal cells send to thalamic nuclei, mainly to lateral geniculate nucleus and inferior, lateral, and medial pulvinar nuclei. Half of layer-6 pyramidal cells send to lateral geniculate nucleus, and others send to claustrum, hippocampal system, and anterior cingulate sulcus motor-system higher planning levels. Pyramidal cells with short dendrites, not reaching into layer 1, send to other cerebral cortex regions. Excitatory extrinsic axons come from pyramidal cells. Pyramidal cells also send to local neurons using axon collaterals.
Pyramidal cells inhibit stellate cells. Pyramidal-cell to stellate-cell ratio is two to one.
processing
Pyramidal cells have high spontaneous activity and large receptive fields. Sustained intracellular current causes high-frequency action potentials {regular spiking cell}, which decrease within 50 to 100 milliseconds.
All vertebrate sense cells {sensory cell} developed from ectothelial cell type.
Visual-cortex cells {simple cell} can receive from lateral geniculate nucleus (LGN) ON-center and OFF-center neurons. Simple cells receive from both eyes but process one eye faster and so have ocular dominance. Simple cells have more precise tuning than LGN or retinal cells. See Figure 1.
lines
Cells that compare ON-center and OFF-center neuron superpositions can find boundaries and heighten contrasts. Simple cells can detect lines, edges, stripes, or gratings. Simple cells can detect 12 to 30 line, edge, stripe, or grating orientations {orientation tuning, cell}. Simple cells have different receptive field sizes and detect different line, edge, stripe, or grating spatial frequencies and widths.
color
Some simple cells detect color.
movement
Some simple cells detect movement.
arrays
Simple cells have arrays in topographic maps. See Figure 2.
Neurons {smooth stellate cell} can send only to superficial and deep pyramidal cells.
Neurons {spiny stellate cell} can send only to superficial and deep pyramidal cells. Spiny-stellate-cell inhibitory axons connect horizontally only up to 100 to 200 microns away.
Cortical layer-4 cells {stellate cell} can detect bars, slits, and edges, in static pictures, at 20 orientations. Stellate cells have small receptive fields and low spontaneous activity. Smaller stellate cells excite easier. Cerebellum stellate cells receive excitation from parallel fibers and laterally inhibit adjacent-column Purkinje cells.
Neurons {superficial pyramidal neuron} can send unmyelinated collaterals, with no terminal branches, sideways to tight terminal clusters. Neurons repeat this for many millimeters: every 0.43 mm in primary visual cortex, every 0.65 mm in secondary visual areas, every 0.73 mm in sensory strip, and every 0.85 mm in monkey motor cortex. Macrocolumns of similar emphasis connect by synchronizing excitation.
Brain output neurons {tufted cell} can be secondary.
Neurons {TH+ neuron} can make serotonin and affect Parkinson's disease.
Nerve chemicals {neural chemical} {nerve chemical} are hormones, ions, modulators, receptors, regulators, transmitters, and structures.
transverse motion
Only biological cells use transverse ion motion to make depolarization wave. If axon has nodes of Ranvier, depolarization jumps from node to node and transverse ion motion is same strength in all directions around axon circumference. If axon has no nodes of Ranvier, transverse ion motion is all around axon circumference but is most at least-resistance point. Ions repel each other, so differences are small. Depolarization waves travel down lines on axon surfaces, following least-resistant path, and can spiral down axon.
Calcium ions move from mitochondria and endoplasmic reticulum through channels {calcium ion channel} onto receptors. Calcium ions phosphorylate synapsin proteins and cause vesicle fusion with membrane, to trigger neurotransmitter release. Calcium ions clear from receptors by active transport back into mitochondria and endoplasmic reticulum.
Dendrite voltage-gated Ca++ channels can provide non-linear coupling between inputs.
Transmitter-gated calcium-ion channels are like other channels {P/Q-type calcium channel}.
Serotonin and cyclic AMP regulate calcium-ion entry into cells, including neurons.
Cells have chloride-ion channels {chloride ion channel}.
Cells have seven potassium-ion channel types {potassium ion channel}.
cAMP mediated receptors {S channel} close potassium-ion-channel type. cAMP mediated receptors reduce a potassium-ion-channel size, to allow longer action potentials and allow more calcium ion to flow into presynaptic area and increase transmitter release.
Cells have sodium-ion channels {sodium ion channel}.
Brain neurons secrete chemicals {neurohormone} that affect other neurons more slowly than neurotransmitters. Neurohormones can cause signal pattern from neuron group [McEwen, 1976].
Circulating vasoconstrictor molecules {angiotensin} can bind to presynaptic noradrenergic nerve terminals. Kidney renin enzyme changes angiotensinogen to angiotensin.
Bone proteins {bone morphogenetic proteins} regulate whether neural precursors become neurons or glia.
Brain releases peptides {bradykinin} in response to injury to stimulate neurons.
Hormones {brain-derived neurotrophic factor} (BDNF) can increase NMDA-receptor phosphate binding and can develop immature sympathetic and sense neurons and glia.
Most endocrine-hormone or neurotransmitter gastrointestinal-system peptides {gut-brain peptide} {brain-gut peptide} {brain-gut axis} are also brain hormones or neurotransmitters. Most gastrointestinal system peptide receptors are also in brain. Brain and gut peptides include bombesin, cholecystokinin (CCK), gastrin, motilin, neurotensin, pancreatic polypeptide, secretin, substance P, and vasoactive intestinal peptide (VIP).
Medullary-motor-nuclei transmitters {calcitonin-gene-related peptide} (CGRP) can regulate phenotypic expression.
brain peptide {carnosine}.
Glycoproteins {neurotrophin} {cell adhesion molecule} (CAM) {axon guidance molecule} can guide growing nerve processes to appropriate target neurons. Hormones develop immature neurons and glia. For example, neurotrophin-3 increases oligodendrocyte number. 1,1-CAM protein helps begin myelination.
Peptides {cholecystokinin} (CCK) can cause satiation by binding to solitary tract nucleus (NTS) receptors, enhances dopamine actions, and is in gut, cerebral cortex, medulla oblongata, solitary tract nucleus, and ventral midbrain.
Hormones {ciliary neurotrophic factor} (CNTF) can decrease immature neuron and glia death and supports eye ciliary-ganglion parasympathetic neuron survival. Perhaps, CNTF is survival or trophic factor, mitogen, or transmitter-regulating factor for other neurons.
Brain hormones {circulating hormone}, such as angiotensin, calcitonin, glucagon, and insulin, can release into blood.
Three genetically different endorphin peptide families are proopiomelanocortin (POMC), proenkephalins, and prodynorphin {dynorphin}. Dynorphin peptides act like opioids. Gut, posterior pituitary, hypothalamus, basal ganglia, and brainstem make prodynorphin. Leucine-enkephalin leads to dynorphin. Dynorphin in nucleus accumbens neurons inhibits VTA neurons and so reduces dopamine.
Hormones {galanin} can be in basal forebrain and hypothalamus.
Brain and gut peptide hormones {gastrin}| can control stomach secretion.
Hormones {glial growth factor-2} (GGF-2) can increase glia number.
Hormones {glial-derived neurotrophic factor} (GDNF) {glial cell line-derived neurotrophic factor} can make new axon branches in motor neurons.
Hormones {gonadotropin-releasing hormone} can release gonadotropin in hypothalamus.
Hormones {growth-hormone-releasing hormone} can release growth hormone in hypothalamus.
Hypophysis makes oxytocin, neurophysins, and vasopressin {hypophyseal hormone} {neurohypophyseal hormone}.
Hormones {hypothalamic releasing hormones} can release hormones, such as growth-hormone-releasing, gonadotropin-releasing, and luteinizing-hormone-releasing hormones, from hypothalamus.
Hormones {insulin-like growth factor} (IGF-1) can help develop immature neurons and glia.
Peptides {kyotorphin} can act as opioids.
Hormones {lipotropin} can be from pituitary.
Norepinephrine, epinephrine, dopamine, and serotonin {monoamine}| are slow-acting neuromodulators, come from brainstem, and affect arousal and sleep.
Peptides {motilin} can be in gut and cerebellum.
Hormones {nerve growth factor} (NGF) can go into sympathetic-neuron and sense-neuron axon terminals and transport to cell body, where it increases transmitter levels. Olfactory bulb, cerebellum, and striatum make nerve growth factor and nerve growth factor receptor.
enzyme
In hippocampal neurons, NGF increases choline acetyltransferase (CAT), which synthesizes acetylcholine and can reverse poor spatial memory.
disease
NTRK1 gene makes neurotrophin tyrosine kinase receptor type 1. NTRK1 gene mutation causes rare autosomal recessive disease (CIPA) with pain insensitivity, no sweating, self-mutilation, fever, and mental retardation.
Molecules {netrin} attract and repel axons to guide axon directions.
Peptides {neuropeptide} can have high concentrations in nervous-system regions and low concentrations in other cells and organs. Neuropeptides include brain-gut peptides, circulating hormones, hypothalamic releasing hormones, neurohypophyseal hormones, opioid peptides, pituitary hormones, bradykinin, carnosine, epidermal growth factor (EGF), neuropeptide Y, proctolin, and substance K. Brain hormones, such as opioids, act slowly [McEwen, 1976].
Peptides {neuropeptide Y} (NPY) can be in cerebral cortex and medulla oblongata. Arcuate-nucleus appetite region sends neuropeptide Y to second appetite region.
Hypophysis makes nerve hormones {neurophysin}.
Steroids {neurosteroid} can induce sleep, be analgesic at high concentration, and come from cholesterol or progesterone.
Peptides {neurotensin} can be in gut, hypothalamic arcuate nucleus, medulla oblongata, retina, solitary tract nucleus, and ventral midbrain.
Hormones {notch growth factor} can regulate whether neural precursors become neurons or glia.
Macrophages make protein {oncomodulin} that regenerates nerve.
Peptides {pancreatic polypeptide} can be in brain and gut.
Peptides {peptide hormone}, such as endorphins and enkephalins, can produce slower effects than neurotransmitters and come from 20% of inhibitory cells. Enzymatic hydrolysis inactivates such peptides, so they do not reabsorb into synaptic terminals or glial cells [McEwen, 1976].
Pituitary hormones {pituitary hormone} are alpha melanocyte-stimulating hormone (alpha MSH), corticotropin (ACTH), growth hormone (GH), lipotropin, luteinizing hormone, prolactin, somatotropin, and thyrotropin.
Hormones {presenilin} can decrease neural stem-cell division.
Peptides {proctolin} can be in brain.
Peptides {secretin} can be in brain and gut.
Molecules {semaphorin} can attract and repel axons to guide axon directions.
Thalamus, cortex, and hippocampus hormones {somatostatin} (SS) can mimic hypothalamus sympathetic-neuron substance-P regulation. Somatostatin treats diabetes.
Hormones {somatotropin} can be in pituitary.
Hormones {sonic hedgehog growth factor} {sonic hedgehog gene} can regulate immature-neuron cell division. Sonic hedgehog gene activates pathway that affects central-nervous-system development.
Peptides {substance K} can be in brain.
Proteins {survival motor neuron proteins} can preserve motor neurons.
Chemicals {neuroregulator} {neuromodulator} can amplify or negate neurotransmitters by altering transmitter-receptor interactions, changing ion flux, or activating neuroreceptor enzymes.
Molecules {ampakine} increase glutamine binding to AMPA receptor and increase glutamate release from AMPA receptor, affecting memory and cognition.
Molecules {diacylglycerol} (DAG) can phosphorylate ion channels.
Molecules {inositol triphosphate} (IP3) can phosphorylate ion channels.
Proteins {alpha-integrin} can bind to cell membranes, maintain long-term potentiation (LTP), and aid memory.
Enzymes {protein kinase Mz} can be necessary and sufficient for long-term potentiation.
Chemicals {retrograde messenger} can diffuse back from postsynaptic to presynaptic membrane. For example, upon protein-kinase activation, nitric oxide synthase makes nitric oxide from l-arginine. Nitric oxide diffuses back from postsynaptic to presynaptic membrane and causes increase in vesicle release, if membrane is still active.
Proteins {beta-adrenergic catecholamine receptor} {beta-receptor} {adrenergic catecholamine} can bind catecholamines. Binding couples to G protein and adenylate cyclase metabolism. Beta-receptor protein strongly binds ISO, binds epinephrine, and weakly binds norepinephrine. Binding can cause vasodilation, uterine contraction inhibition, cardiac stimulation, and bronchodilation. If guanosine triphosphate (GTP) is present, beta-receptors have only low-affinity catecholamine binding.
Proteins {agrin} can cluster other proteins between neurons and muscle cells and at immune synapses.
Sympathetic noradrenergic nerve terminal proteins {alpha-receptor}, such as alpha-2 receptor, bind to norepinephrine strongest, epinephrine middle, and isoproterenol (ISO) lowest. Binding can cause vasoconstriction, uterine contraction, and mydriasis. Alpha-receptor agonist and alpha-receptor antagonist affect alpha-receptors.
Proteins {AMPA receptor} {aspartate receptor} can bind aspartate, glutamate, and glutamine. Binding is fast, opens sodium ion channels, and causes excitation.
Proteins {angiotensin II receptor} can bind angiotensin in presynaptic noradrenergic nerve terminals.
Neuron receptors {autoreceptor} can be on presynaptic membranes, for negative feedback.
Nociceptors {cannabinoid receptor} (CB1) can have cannabis receptors. Anandamide, 2-arachidonoyl glycerol (2-AG), and marijuana delta-9-tetrahydrocannabinol (THC) bind in hypothalamus, basal ganglia, amygdala, brainstem, hippocampus, cerebellum, and neocortex. Hypothalamus affects appetite, sex, and hormones. Basal ganglia affect motor acts and planning. Amygdala affects emotion, anxiety, and fear. Brainstem affects pain and reflexes. Hippocampus affects memory and learning. Cerebellum affects motor acts. Neocortex affects sense qualities and cognition.
2-AG flows from receptor cell back to transmitting cell to decrease GABA {depolarization-induced suppression of inhibition} (DSI) [Earleywine, 2002] [Grinspoon and Bakalar, 1993].
immune
CB2 receptor is only in immune system.
Proteins {CD45 protein} can be for synapse and immune-synapse adhesion.
Proteins {D1 receptor} {D1 dopamine receptor} {dopamine D1 receptor} can bind dopamine. Binding is slow, uses cAMP, opens potassium ion channels, closes calcium ion channels, and inhibits.
Proteins {D2 receptor} {D2 dopamine receptor} {dopamine D2 receptor} can bind dopamine. Binding is slow, uses cAMP, opens potassium ion channels, closes calcium ion channels, and inhibits.
Dopamine receptors {DRD4 dopamine receptor} can be in brain. Perhaps, DRD4-gene allele {attention-deficit hyperactivity disorder, dopamine} arose 40,000 years ago and allowed bolder and more-curious personalities.
Receptor complexes {GABA receptor} {gamma-aminobutyric acid receptor} can bind GABA.
types
Type A {GABA-A receptor} is fast, opens chloride-ion channels, and inhibits. Type B {GABA-B receptor} is slow, opens potassium-ion channels, closes calcium-ion channels, uses IP3 and DAG, inhibits, and uses second-messenger system, probably cyclic AMP.
parts
Endogenous benzodiazepine-receptor protein is part of GABA-receptor complex and increases extent or period of GABA-operated chloride-ion channel opening.
drugs
Benzodiazepines and anxiety-reducing neuromodulators {anxiolytic drug, GABA} increase GABA affinity for GABA neuroreceptors and enhance GABA-mediated synaptic potentials. Perhaps, anesthetics bind to GABA-A. Perhaps, neurosteroids from progesterone and cholesterol bind to GABA-A.
Proteins {glycine receptor} can bind glycine. Binding is fast, opens chloride-ion channels, and inhibits. Dorsal-horn neurons have glycine receptors for inhibition. ACEA competitively blocks glycine receptor. Strychnine affects glycine receptor. Prostaglandins block glycine receptors and so excite dorsal horn neurons.
Outer-membrane receptors {G-protein-coupled receptor} (GPCR) can have seven alpha helices in cell membrane and has active protein part inside cell membrane next to G protein. For example, olfactory sense neurons have membrane receptors that activate G protein. For slow 0.1-second to 10-second effects, receptor activates G protein, which binds GTP to make second messengers such as cyclic AMP, diacylglycerol (DAG), or inositol triphosphate (IP3), which phosphorylate ion channels.
Ion channels {ionotropic receptor} {transmitter-gated ion channel} can bind neurotransmitters, such as glutamine, and then open quickly. Response to ion flows is 10 to 30 times faster than metabolotropic response.
Proteins {kainate receptor} can bind glutamate. Binding is fast, opens sodium ion channels, and excites.
Proteins {M receptor} can bind acetylcholine. Binding is slow, opens calcium ion channels, excites or inhibits, and uses IP3, cAMP, or DAG.
Neurotransmitters, such as glutamate, can bind to receptors {metabotropic receptor}, which affect G protein, which activates adenyl cyclase, which changes ATP to cAMP, which binds to cAMP-dependent protein-kinase regulatory subunit, which affects catalytic subunit, which phosphorylates protein, which opens or closes ion channels, which increases calcium ion. Such receptors amplify signals 100-fold and cause cell-effect patterns.
factors
Calcium ion and other second messengers affect cAMP activity. Metabolism uses IP3 and DAG.
speed
Response to neurotransmitter-neuroreceptor activation is 10 to 30 times slower than ionotropic response.
Proteins {mGluR5 receptor} can bind glutamate and affect cocaine dependence.
Acetylcholine receptors {muscarinic ACh} can use second messenger.
Proteins {N receptor} can bind acetylcholine. Binding is fast, opens sodium ion channels, and excites.
Cell membranes between two neurons or immune cells can form tubes {nanotube, cell} that can transfer calcium, proteins, or viruses.
Protein receptors {neuropilin} can be at synapses and immune synapses.
Nicotine is similar to acetylcholine. Immune cells and neural cells have acetylcholine receptors. Nicotine inhibits cytokine release by macrophages. Proteins {nicotinic receptor} {alpha-7 nicotinic receptor} {alpha-7 acetylcholine receptor} can bind nicotine and stimulate NMDA receptors [Granon et al., 2003].
If postsynaptic membrane depolarizes and glutamate releases from presynaptic neurons, postsynaptic neuron proteins {NMDA receptor, neuron} {N-methyl-D-aspartate receptor} can bind glutamate [Miller et al., 1989] [Tang et al., 1999] [Watkins and Collingridge, 1989] [Wittenberg and Tsien, 2002]. Binding is fast.
effects
Binding opens sodium ion channels, opens potassium ion channels, opens calcium ion channels, and excites or inhibits. Binding increases cell response non-linearly. Binding rapidly controls connectivity between cells, allowing transient cell assemblies.
In neocortex pyramidal cells, binding causes slow, long lasting ESP that rises to peak in 10 milliseconds to 75 milliseconds and can stay altered for days or years.
process
NMDA receptors have magnesium ion inside. Glutamate binding removes magnesium ion and allows calcium-ion flow. Calcium ion aids protein-kinase phosphorylation. Protein kinases then phosphorylate AMPA receptors for early LTP. Protein kinase A (PKA), MAP kinase (MAPK), and calcium/calmodulin protein kinase (CaMK) phosphorylate CREB. In cell nucleus, CREB activation turns on genes that make late LTP proteins. Active synapses have chemical sites {molecular tag} that bind late LTP proteins.
factors
Brain-derived neurotrophic factor (BDNF) increases NMDA-receptor phosphate binding.
antagonists
Ap5, CGS 19755, CPP, and D-CPP-ene affect NMDA receptor. NMDA antagonists can block visually induced activity in visual-cortex superficial layers, but not deep layers.
Proteins {presynaptic neuroreceptor} can enhance or reduce neurotransmitter release, by responding to previously released neurotransmitter {autoregulation} or to other neurotransmitters or neuromodulators {heteroregulation}. Presynaptic neuroreceptors regulate noradrenaline release from heart, spleen, vas deferens, and brain. Central and peripheral adrenergic-nerve-axon synapses can have both negative and positive feedback.
Proteins {talin} can be for synapse and immune-synapse adhesion.
Proteins {calmodulin protein kinase} {calcium protein kinase} (CaMK) {calcium-calmodulin protein} can phosphorylate, enter cell nucleus, and activate CREB gene.
Proteins {calmodulin-binding protein} can bind to calmodulin and perhaps bind to actin.
At high concentrations, cAMP-dependent protein-kinase catalytic subunits {cAMP-dependent protein kinase} phosphorylate transcription factors, such as cAMP-response element binding protein-1 (CREB-1), C/EBP transcription factor, and tissue plasminogen activator (tPA), which express genes in cell nucleus to initiate change or growth. Repeated action potentials, from stress or high activity, make cAMP-dependent protein kinase concentration high.
Calcium ion entry can activate proteins {cAMP-response element} {cyclic-AMP response element} (CRE) (CRE-1) {cAMP-response element binding protein-1} (CREB-1) {CREB protein} that bind to regulatory regions and activate cyclic-AMP and cyclic-AMP-receptor genes. CREB also activates immediate early genes, such as ubiquitin hydrolase and C/EBP transcription factor, to initiate synaptic growth. CREB regulates endorphin production.
Enzymes {caspase 9} can cause neuron death and so prune networks.
Proteins {C/EBP transcription factor} {C-EBP transcription factor} can activate synaptic protein genes.
Molecules {CREB enhancer} can increase CREB protein by inhibiting phosphodiesterase.
Molecules {CREB suppressor} can decrease CREB protein.
Enzymes {mitogen-activated protein kinase} {MAP kinase} (MAPK) can phosphorylate CREB-2 repressor to prevent CREB-1 binding to CRE-1. MAPK8 regulates cell movement.
Amines {octopamine} can be neuromodulators for behavior.
Enzyme series {phospholipid cascade}| can regulate intracellular phospholipid by regulating gene transcription. Calcium ion, phosphorylation, and phospholipid pathways regulate each other.
Enzyme series {phosphotidylinositol cascade} can regulate intracellular phospholipid by regulating gene transcription.
Enzymes {protein kinase A} (PKA) can phosphorylate and activate mitogen-activated protein kinases.
Proteins {spectrin} {fodrin} can bind to actin and calmodulin.
Proteins {synapsin} can phosphorylate by causing calcium-ion influx.
Proteins {tissue plasminogen activator} (tPA) can activate genes for neuron terminals and spines.
Amines {tyramine} can be neuromodulators for behavior.
Enzymes {tyrosine hydroxylase} (TH) can be rate-limiting enzyme in catecholamine biosynthesis. Increased neuronal firing increases catecholamine-pathway enzyme synthesis in perikarya. Axons transport enzymes to axon terminals. Catecholamine pathway requires pteridine, iron, and oxygen and converts tyrosine to L-DOPA. Dopamine and norepinephrine inhibit tyrosine hydroxylase by feedback inhibition. Stressful stimuli increase TH. Acetylcholine phosphorylates TH using cyclic AMP.
Enzymes {ubiquitin hydrolase} can be in ubiquitin proteasomes, break down PKA regulatory subunit in sense neurons, and so enhance catalysis, typically when cAMP is decreasing.
Proteins {fibronectin} can be in extra-cellular matrix.
Proteins {laminin} can be in extra-cellular matrix.
Proteins {telencephalin} can be cell-adhesion molecules.
Proteins {tubulin} can be in microtubules.
Neurons transfer molecules {neurotransmitter}|.
purposes
Neurotransmitters can transfer signals, mediate rapid electrical communication, foster neuron survival and pathway formation, elicit synaptic changes, and trigger biochemical changes that modify subsequent signals.
types
Transmitter types are amino acidergic, catecholamine, cholinergic, monoaminergic, peptides, and purines. Cholinergic includes acetylcholine. Neurotransmitters include aspartic acid, dopamine, epinephrine, gamma-aminobutyric acid (GABA), glutamic acid, glycine, histamine, norepinephrine, octopamine, and serotonin.
change
Neurotransmitter used by neuron can change over time. Transmitter changes can last days to weeks, while environmental stimuli last seconds to minutes. Neuron can release transmitter at low stimulation, peptide at high stimulation, and both at intermediate stimulation.
vesicles
Cholinergic, monoaminergic, and amino-acidergic neurons synthesize neurotransmitters mostly in nerve terminals. Synaptic vesicles in unmyelinated axon and cell-body regions release neurotransmitters. Released packets have 1000 molecules. Storage vesicles or granules have only one neurotransmitter type. They release independently.
Peptidergic cells synthesize large proteins in cell body and then split them into active peptides.
Individual neurons all have multiple transmitters.
vesicles: dendrites
Mitral cells, substantia nigra dopaminergic neurons, and olfactory bulb GABAergic axonless granule cells have synaptic vesicles in dendrites.
Acetylcholine {acetylcholine, memory} (ACh) can be a fast neurotransmitter or slow modulator.
modulator
ACh regulates neurite nerve process outgrowth and aids neuronal population survival.
location
ACh is in autonomic parasympathetic ganglia, basal forebrain, caudate nucleus, medulla motor nuclei, neuromuscular synapse, Meynart basal nucleus, putamen, pons, superior olive, spinal cord, cranial-nerve motor nuclei, cerebral-cortex bipolar cells, and submandibular-salivary-gland postsynaptic parasympathetic neurons.
excitation
Acute bipolar-cell or parasympathetic-neuron stimulation releases only acetylcholine. Chronic excitation releases both VIP and acetylcholine, in ratio depending on stimulus duration.
VIP
Acetylcholine inhibits VIP release by interacting with neuron receptors. VIP inhibits acetylcholine release by binding to neuron VIP receptors.
drug
Acetylcholine can treat senile dementia or aid memory.
enzyme
Acetylcholinesterase enzyme hydrolyzes acetylcholine. Added cholinesterase decreases memory.
Enzymes {acetylcholinesterase} can hydrolyze acetylcholine. Added cholinesterase decreases memory.
Amino-acid neurotransmitters {amino acidergic neurotransmitters} include glutamate and aspartate.
Amino acids {aspartate} {aspartic acid} can be excitatory transmitters.
Norepinephrine (NE), dopamine (DA), and epinephrine (E) are 3,4-dihydroxy phenylethylamine derivatives {catecholamine}| (CA) {biogenic amine}.
locations
Catecholamines come from tyrosine in peripheral sympathetic neurons, adrenal medulla, chromaffin tissue, and brainstem nuclei.
Adrenal medulla makes and stores catecholamines in response to stress.
metabolism
Catecholamines phosphorylate postsynaptic receptor proteins, like adenylate cyclase, in vascular smooth muscle, heart, liver, adipocytes, and many brain neurons.
Uptake into presynaptic nerve terminal inactivates catecholamines. Desipramine and cocaine inhibit uptake.
Stimulation by serotonin facilitates presynaptic catecholamine release, which increases intraneuronal cAMP, which inactivates potassium-ion channel, which allows more calcium ion in.
Phenylethylamine derivatives release catecholamines. Bretylium and guanethidine have a highly basic center, linked by one-carbon or two-carbon chain to ring, and block catecholamine release.
vesicles
Catecholamines are in membrane-bound vesicles. Reserpine interferes with catecholamine storage in vesicles. Catecholamine release from vesicles uses exocytosis. Release requires calcium ion.
functions
Catecholamines can cause tachycardia, peripheral vasoconstriction, mydriasis, and peristalsis inhibition.
Choline transmitters {cholinergic neurotransmitters} include acetylcholine [Hille, 2001] [Hobson, 1999] [Steriade and McCarley, 1990] [Perry and Young, 2002] [Perry et al., 1999] [Perry et al., 2002] [Woolf, 2002].
Biogenic amines {dopamine}| (DA) are in hypothalamic arcuate nucleus, midbrain nigrostriatal, and ventral midbrain. Dopamine affects reward processing. It initiates and maintains anticipation behavior, novelty, attention, and action selection. Dopamine interacts with amine and choline modulators.
Dopaminergic neurons use adrenaline or epinephrine, noradrenaline or norepinephrine, dopamine, or serotonin. Dopaminergic neurons can make highly branched networks with small-diameter ascending and descending fibers, low frequency potentials, and slow conduction velocities.
Molecules {effector molecule} can work rapidly and break down or reabsorb rapidly.
Fast-acting inhibitory neurotransmitters {gamma-aminobutyric acid} (GABA) can come from glutamate and can be in basal ganglia, cerebellum, cerebral cortex, hippocampus, hypothalamus, retina, striatonigral, thalamus, and ventral pallidum. 20% of inhibitory neurons, mostly interneurons, use GABA. Valium enhances GABA activity.
Fast-acting excitatory amino-acid neurotransmitters {glutamate} {glutamic acid} can be in spinal cord, brainstem, cerebellum, hippocampus, and cerebral cortex. 60% of excitatory neurons, mostly projection neurons, use glutamate. Glutamate affects dopamine.
Amino-acid inhibitory transmitters {glycine} can be in retina and spinal cord.
Amines {histamine, transmitter} can be in pituitary and medial hypothalamus.
Monoamine transmitters {monoaminergic neurotransmitter}| include norepinephrine, epinephrine, dopamine, and serotonin.
Molecules {nitric oxide}| released by postsynaptic terminals can bind to presynaptic terminals. Enzymes {nitric oxide synthase} (NOS) make nitric oxide from arginine. L-nitro-arginine methyl ester (L-NAME) inhibits nitric-oxide synthesis.
Neurotransmitters {peptide neurotransmitter} can have several amino acids.
Spermidine and spermine competitively inhibit amine receptors {polyamine receptor}.
Purine neurotransmitters {purine neurotransmitter}| include AMP and GMP.
Vasoactive monoamines {serotonin}| {5-hydroxytryptamine} (5-HT) can inhibit or excite metabolic activity, depending on receptor. Serotonin comes from tryptophan.
location
Serotonin is in area postrema, medulla oblongata, pineal gland, gut parasympathetic system, and pons raphé nucleus. Brain has 300,000 serotonergic neurons.
functions
Serotonergic-neuron activity is proportional to arousal, wakefulness, and muscular activity. Serotonin excites cortex pyramidal neurons. It inhibits neurons that receive excitations. It regulates neurite nerve process outgrowth and aids neuronal population survival. It causes or inhibits intestinal contraction. It constricts or relaxes blood vessels. Serotonin enhances substance P release from axons to excite spinal cord. Substance P releases serotonin from terminals inhibited by serotonin.
receptors
Neurons make serotonin and release it into synaptic clefts. Mammals have more than 13 different serotonin receptors. Animals have over 30 different serotonin receptors, which connect to G proteins.
uptake
Serotonin reuptake transport molecules remove serotonin from synaptic clefts. Selective serotonin reuptake inhibitors inhibit serotonin uptake back into cells.
damage
If serotonin level decreases, activity increases. Inhibiting serotonin receptor does not modulate behavior.
derivatives
5-HIAA comes from serotonin and causes higher male social status, more female grooming, and quieter activity.
evolution
Serotonergic neurons and serotonin receptors evolved 500,000,000 years ago. Gene duplication allowed different kinds. Anthropoid apes evolved 40,000,000 years ago and have different promoter sequence for serotonin-reuptake-transport gene than humans do.
Molecules {transporter molecule} can put and get transmitters in synaptic cleft. If synapse has no vesicles, it puts transmitters in cleft.
The evidence is against the hypothesis that synapses release neurotransmitter directly {vesigate} from cytoplasm through membrane pores {operator pore} opened by calcium ions.
Sense receptor stimulation can send signal to spinal cord and then to muscle or gland, resulting in involuntary action {reflex, nerve}|. Stimulus can cause innate, immediate response in muscle or gland. Reflex has only one synapse between muscle or tendon touch receptor and motor neurons to muscle. Brain, body, local excitability, and previous reflex responses can affect reflexes.
types
Stretch reflexes relate to muscle tension, posture, and locomotion. Flexion reflexes follow painful skin stimuli. Reflexes {suprasegmental reflex} can be for one vertebra only {segmental reflex} or for all vertebrae above vertebra. Reflexes {intrasegmental reflex} can involve only one spinal segment. Reflexes {intersegmental reflex} can involve several spinal segments. Reflexes can involve spinal cord, cerebellum, and medulla oblongata. Cerebellum and midbrain automatically control muscle movements {synergy, reflex}. Striatum controls muscles automatically and by association. Neocortex exerts voluntary and regulatory control {state variable}.
Thumb pressed into newborn-foot bottom causes foot and toes to flex {ankle clonus}.
Reflexes {arm reflex} can be in newborns.
Scratching a newborn's foot from toe to heel causes big toe to go up and toes to spread {Babiniski reflex}. In infants, stroking foot side causes big-toe raising. Babiniski reflex disappears at eighteen months old. Adult apes have Babiniski reflex, to grasp tree branches with toes.
Baby reacts to red rattle {Brazelton sensory test}. Baby eyes look ahead during spinning and return to center when spinning stops. Baby can hear bell ring with both ears.
If small object irritates eye, eyelid reflexively closes {blink reflex}.
Reflexes {crossed extension reflex} can be suprasegmental and happen after flexion.
Insects and vertebrates have fast reflexes {escape reflex} to leave situation.
Reflexes {eye reflex} can be in newborns.
Reflexes {eyelid closing reflex} can be in newborns.
Pain causes muscle flexion {flexion reflex}.
Reflexes {inverse stretch reflex} {inverse myotactic reflex} {Golgi tendon reflex} {clasp-knife reflex} can override stretch reflex but is slower because it has two synapses. It works with stretch reflex to maintain posture.
Touching male inner thigh can cause penis erection and testes raising {inner thigh reflex}.
Tapping newborn chin causes masseter muscle to contract {jaw-jerk}.
Avoiding or fleeing is a reflex {large moving object reflex} to large moving objects.
Newborns can react to head-position fast change by extending arms and fingers to side and then in front {Moro reflex}. Moro reflex lasts until six months old.
A one-synapse reflex {stretch reflex} {myotactic reflex} maintains posture and muscle tone. Stretch reflexes relate to muscle tension, posture, and locomotion. Stretch reflexes maintain posture by contracting muscles if they stretch out. Stretch reflex control allows sitting up and other behaviors, after sense organs establish reflexes with motor neurons. Standing, crawling, sitting, walking, and running use spinal-cord reflex circuits, which connect to cerebrum and cerebellum.
Reflexes {necking reflex} can be in newborns.
New stimulus causes attention and turning toward stimulus {orientation reflex} {orienting response}, with increased brain electrical activity, reduced blood flow to extremities, changed skin electrical resistance, increased adrenal steroid hormones, and overt motor activity. Behavior interruption, perception discrepancy, or unexpected stimuli can cause animals to turn toward changes, have more sensitization, and concentrate more. Orienting reflex is automatic and involuntary, not cognitive. It involves acetylcholine neurons. It precedes attention. It processes up to 2000 information bits [Koffka, 1935] [Köhler, 1969] [Palmer, 1999].
ACTH prolongs orientation reflex, and glucocorticoids dull it.
orientation sense
Orienting response precedes slower process {orientation sense} that gathers information about time, place, and person to recognize object. Orientations {shifter circuit, orientation} can be automatic but voluntary and cognitive. Circuits process 50 information bits with each glimpse. Orientation places objects in scenes in short-term memory {pop-out, orientation}, using motion, depth, texture, and color cues.
Eye pupil can open {pupil dilation reflex}|.
Reflexes {pupillary reflex} can be in newborns.
Newborns have reach-and-grasp reflex arm and hand movement {reach-and-grasp reflex}.
Animals can make themselves upright reflexively {righting reflex}.
Touching mouth corner causes newborns to turn and try to suck {rooting response}.
Stimulating a skin point makes same-side leg scratch that point {scratch reflex}. Scratch reflex is suprasegmental.
Jawed vertebrates snap at food {snapping at food reflex}, if small objects move in vision field.
Fear increases startle response {fear-potentiated startle response} {startle response, reflex} {startle reflex}.
Cerebellum and midbrain can coordinate muscle movements {synergy, movement}.
A tendon tap can cause muscle contraction {tendon jerk}. Tendon jerk is simplest and fastest mammalian reflex.
Newborn resists being pulled into sitting position {traction reflex}.
Newborns turn in direction of voices from behind curtains, moving both hands and face {voice reflex}.
After sticking pin into foot sole, newborn foot and leg withdraw {withdrawal reflex}.
Sense-organ neurons {afferent nerve} {afferent fiber} send to ganglia outside brain along spinal cord. Ganglia sense neurons send one axon to brain and one axon to peripheral nerve.
Axons to brain synapse on brain secondary sense neurons. Secondary sense neurons send to cerebellum or thalamus. Thalamus neurons send to neocortex. Neocortex neurons send back to thalamus and to cortex association areas. Association cortex neurons send to hippocampus and amygdala. Hippocampus and amygdala neurons send to hypothalamus.
All these cortical regions send to corpus striatum. Corpus striatum neurons send to globus pallidus. Globus pallidus neurons send to reticular formation and thalamus.
muscle
Muscle sense-cell afferent is wide axon and has one synapse, because large axons have lower thresholds.
skin
Skin afferent is fine axon with several synapses, because fine axons have higher thresholds.
Brain neurons {efferent nerve} {efferent fiber} send to sense organs, muscles, and glands.
Large myelinated axons {A fiber} can come from motor or sense neurons. A fibers {A-alpha nerve} {alpha fiber} can be for proprioception or be somatic motor axons. Sensory A fibers {A-beta nerve} {beta fiber} can be for touch or pressure and travel in spinal cord from trigeminal nucleus. Intermediate-size myelinated sensory A fibers {A-delta nerve} {delta fiber} can be for pain, temperature, or touch and travel in spinal cord to trigeminal nucleus. Motor A fibers {A-gamma fiber} {gamma fiber} can be for muscle spindles.
Small myelinated axons {B fiber} are preganglion autonomic nerves.
Small unmyelinated axons {C nerve} {C fiber} are postganglion sympathetic autonomic nerves or are dorsal root nerves for pain, temperature, and reflexes. Unmyelinated sense-nerve axons travel from spinal cord dorsal roots to trigeminal nucleus. Unmyelinated axons have few branches.
Dopamine-secreting neurons {dopamine neuron} are for goals.
Sensory axons {Ia fiber} can be for muscle spindle and annulospiral endings.
Sensory axons {Ib fiber} can be for Golgi tendon organ.
Sensory axons {II fiber} can be for muscle spindle, flower spray ending, touch, or pressure.
Sensory axons {III fiber} can be for pain, temperature, and touch.
Neurons {interneuron}| can connect across two nerve pathways. After pathway neuron excites them, interneurons typically inhibit or excite other-pathway neurons. Interneurons can detect correlations among local neuron signals. They note constancies and covariances between pathways. Symmetric connections coordinate pathway neurons in ganglia and cortex, especially in topographical maps. Asymmetric inhibitory connections among neurons and interneurons allow associative learning. Interneurons arose from neuron duplication.
Sensory axons {IV fiber} can be for pain or other receptors.
Fruitfly brain cells {Kenyon cell} receive from electric-shock dopamine cells and from odor cells and possibly send to motor neurons.
Unmyelinated C fibers and slightly myelinated A-delta fibers {nociceptive fiber} go to trigeminal nucleus for noxious stimuli, pain, or punishment.
Medulla respiratory center sends excitatory signals along nerve {phrenic nerve} to diaphragm.
Legs have a main nerve {sciatic nerve}|.
Body neurons {somatic neuron} can connect to striated muscles to perform voluntary actions and can be active or quiet, depending on will.
Spinal cord nerves {spinal nerve} are two per vertebra and include dorsal nerves, ventral nerves, and visceral autonomic nerves.
Spinal nerves include visceral branches {autonomic nerve}.
Spinal nerves can be on back {dorsal nerve}.
Spinal nerves can be on side and front {ventral nerve}.
Head has cranial nerves 1 through 12 {cranial nerve}.
Cranial nerve 1 {olfactory nerve} {cranial nerve 1} {cranial nerve I} has axons from nose olfactory-sense neurons, through cribriform plate, to olfactory bulb. Vertebrate smell uses first cranial nerve.
Cranial nerve 2 {optic nerve} {cranial nerve 2} {cranial nerve II} is from retina to thalamus. It leaves the retina at a location with no receptors {optic disk}.
Cranial nerve 3 {oculomotor nerve} {cranial nerve 3} {cranial nerve III} sends to extrinsic eye muscles, upper eyelid elevator muscle, ciliary muscle, and pupil sphincter muscle. Extrinsic eye muscles are inferior oblique, superior rectus, inferior rectus, and medial rectus, but not lateral rectus or superior oblique.
Cranial nerve 4 {trochlear nerve} {cranial nerve 4} {cranial nerve IV} sends to superior oblique eye muscles.
Cranial nerve 5 {trigeminal nerve} {cranial nerve 5} {cranial nerve V} is from face and carries smell coolness or hotness.
Cranial nerve 6 {abducens nerve} {cranial nerve 6} {cranial nerve VI} sends to lateral rectus eye muscles.
Cranial nerve 7 {facial nerve} {cranial nerve 7} {cranial nerve VII} is from face and has branch {chorda tympani nerve} from anterior mobile tongue that travels with trigeminal-nerve lingual branch as it leaves tongue, goes to middle ear, goes to brain, and signals taste.
Cranial nerve 8 {auditory nerve} {vestibulocochlear nerve} {cranial nerve 8} {cranial nerve VIII} is from inner ear and has cochlear-nerve axons, from hair cells to brain, and vestibular-nerve axons, from vestibule to brain.
Cranial nerve 9 {glossopharyngeal nerve} {cranial nerve 9} {cranial nerve IX} is from pharynx and controls swallowing, tasting, and saliva release.
Cranial nerve 10 {vagus nerve, cranial nerve}| {cranial nerve 10} {cranial nerve X} goes from heart, lungs, stomach, intestine, larynx, esophagus, and aorta to nucleus tractus solitarius. It connects brain to lungs, heart, and intestines.
Cranial nerve 11 {spinal accessory nerve} {cranial nerve 11} {cranial nerve XI} is from shoulder.
Cranial nerve 12 {hypoglossal nerve} {cranial nerve 12} {cranial nerve XII} is from tongue.
Cells {glia}| can provide neuron covering and environment.
covering
Glia cover nerve surfaces, except at synapses and nodes of Ranvier.
structure
Glia provide paths for migrating neurons.
properties
Glia are contractile. Glia can divide. Glia do not conduct. Glia do not interact electrically with neurons. Perhaps, glia are polarizable [Cornell-Bell et al., 1990] [Laming et al., 1998] [Sanderson, 1996].
types
Oligodendrocytes and astrocytes are macroglia. Macrophages are microglia.
chemicals
Glia make myelin, which surrounds axons. Glia make amino acids for neurons. Glia maintain extracellular fluid chemical concentrations. Glia have cholinesterase, whereas neurons have acetylcholinesterase. Glia have much less RNA than neurons.
chemicals: synapses
Glia respond to ATP that leaves synapses by letting calcium in and changing proteins made. Astrocytes make thrombospondin, which builds synapses.
chemicals: regulation
Glia and neuron membranes, receptors, and chemicals interact. Glia regulate extracellular ion, neurotransmitter, and other small-molecule concentrations. Glia can release reactive oxygen molecules, nitric oxide, prostaglandins, excitatory amino acids, IL-1, and nerve growth factor. Excitatory amino acids are N-methyl-D-aspartate and non-NMDA agonists. These can excite pain-responsive spinal cord neurons and increase neurotransmitter release from nerves that relay pain information to spinal cord.
chemicals: factors
Substances released by neurons affect glia [Araque et al., 1999] [DeLeo and Yezierski, 2001] [Raghavendra and DeLeo, 2003] [Watkins et al., 2001].
numbers
Human brains have nine glial cells for every neuron. Glia-to-neuron ratio is as much as 20-to-1 in humans. Glia are half of brain mass. Rats have four or five glial cells for each neuron. The higher human glia-to-neuron ratio reflects need for more chemical and electrical environments and neural connections [Araque et al., 1999] [DeLeo and Yezierski, 2001] [Raghavendra and DeLeo, 2003] [Watkins et al., 2001].
Macroglia {astrocyte} can be protoplasmic, with branched processes, or fibrous, not branched. They cover blood vessels, neurons, and external brain surfaces. They provide structure and guides neuron migration. They take up potassium ions and neurotransmitters. Some astrocytes repair nervous tissue. Astrocytes affect metabolic disorders and epilepsy.
Glia membranes {blood-brain barrier}| (BBB) {glial membrane} can surround nervous-system blood vessels, delay sodium and potassium ion passage, and block passage of other ions and molecules. BBB is interface between blood capillaries and brain tissue.
Glia connect by gap junctions {gap junction, glia}. Electrical stimulation can spread rapidly through connected glia [Araque et al., 1999] [DeLeo and Yezierski, 2001] [Raghavendra and DeLeo, 2003] [Watkins et al., 2001].
oligodendrocytes or astrocytes {macroglia}.
Central nervous system macrophages {microglia} absorb and digest dead cells. They also receive signals from immune cells. They can react to pathogens. Perhaps, they can receive signals from viruses and damaged nerves. They do not affect normal pain responses but can cause abnormally high pain when they receive signals from immune cells [Kreutzberg, 1996] [Meller et al., 1994] [Watkins et al., 2001]. Astrocytes become active when microglia become active.
Microglia make surface receptors {microglia receptor} for macrophage antigen complex-1 (Mac-1), phagocytosis, and cytotoxic-molecule production, including reactive oxygen molecules, nitric oxide, prostaglandins, and proinflammatory cytokines such as interleukin (IL) and tumor necrosis factor (TNF) [Hopkins and Rothwell, 1995].
Macroglia {oligodendrocyte} makes myelin and wraps from several to 50 axons. Oligodendrocytes affect multiple sclerosis and spinal cord injury.
Males and females have sex organs for making new organisms {reproduction, animal}.
day length
In some birds and small mammals, reproduction cycles depend on number of daylight hours.
sex among humans
Only human females are always ready for sex, have permanent breasts, have continuous ability to have orgasms, have active roles in sexual activities, and are similar in size to males. Human sex can be face to face. Humans have wide territories. Humans have foreknowledge of children. Humans typically do not allow incest, so no old males can dominate female groups. Humans do not have estrus and so do not know exactly when they ovulate. People can have more children almost immediately after having a child, whereas apes wait five to six years between births.
People can have characteristics of both sexes {androgyny}|. Hermaphrodism can cause androgyny.
People have fathers {paternity}.
People conceive more boys than girls {sex ratio, birth}, perhaps from lighter XY sperm compared to XX sperm.
People can study sexual behavior and physiology {sexology}|.
interracial marriage or sexual intercourse {miscegenation}|.
Women can have one man {monandry}|.
Men can have one woman {monogyny}|.
People can dislike marriage {misogamy}|.
People can dislike women {misogyny}|.
Erect penis enters similarly blood-engorged vagina and ejects semen, four milliliters with 3 x 10^8 sperm, by epididymis, vas deferens, and urethra involuntary-muscle orgasm contractions {copulation} {intercourse}|. Only human females can have orgasms in clitoris and/or vagina and uterus. Sperm travel {motile} by tail movements and uterus contractions to oviduct tops. Sperm live 24 to 48 hours. Eggs live 24 to 78 hours.
sexual intercourse {coition}|.
sexual intercourse {coitus}|.
sexual intercourse {coupling}|.
Intercourse can cause pain {dyspareunia} in both men and women.
Fathers can have sexual intercourse with daughters, or mothers can have sexual intercourse with sons {incest}|.
Increased blood flow causes vasocongestion, which creates penis erections in males and vaginal lubrication {transudorific reaction, vagina} in females.
Glans penis or clitoris stimulation builds to muscle contractions {orgasm}|.
physiology
Men and women sexual physiologies are essentially the same. First, physical or psychological sexual stimulation causes more blood flow, as heart rate increases. Increased blood flow causes vasocongestion, which creates male penis erection and female vaginal lubrication {transudorific reaction, orgasm}. Then vagina lengthens and increases diameter, especially inner third. Penis increases diameter and length. Vasocongestion causes clitoris and breast nipples to become erect. Then involuntary muscular contractions trigger, causing male orgasm and seminal-fluid ejaculation. In males, glans penis has orgasm. In females, orgasm can be in clitoris and/or vagina.
female
Female sexual stimulation is an autonomic process and happens at clitoris and other body areas. Female orgasm has involuntary contractions of pubococcygeal muscles surrounding last third of vagina. Clitoral stimulation must spread, and this depends on personality and socially conditioned inhibitions. Orgasms differ in completeness and emotional satisfaction.
Females do not have equivalent of ejaculation.
Females can have orgasms by coitus but not by masturbation {masturbatory orgasmic dysfunction}, orgasms by masturbation but not by coitus {coital orgasmic dysfunction}, or only sporadic orgasms {random orgasmic dysfunction}.
male
Males can have primary or secondary impotence, premature ejaculation, and inability to ejaculate. Squeezing glans penis can temporarily inhibit ejaculation.
Inserting penis into anus {sodomy}| can be for sexual pleasure.
Spanish fly comes from beetles, stimulates GI tract, and increases blood flow {aphrodisiac}|.
People can like to display sexual organs in public {exhibitionism}|.
People can believe that objects {fetish}| can have magic or sexual power.
During sexual play, people can bite neck or shoulder {hickey}.
Men can wear women's clothes {transvestism}|.
People can stimulate themselves sexually {autoeroticism}|.
masturbation {onanism}|.
masturbation {self-abuse}.
Mouth and tongue can stimulate female sex organs {cunnilingus}|.
Mouth and tongue can stimulate penis {fellatio}|.
Man can perform cunnilingus while woman performs fellatio {sixty-nine}.
Males and females can use various methods {contraception}| to prevent egg fertilization or implantation and thus pregnancy. Females can use estrogen-progesterone chemicals, vaginal spermicides, intrauterine devices, cervical covers, and tubal ligation. Males can use testosterone chemicals, condoms, and vasectomy surgery.
Cotton-seeds phenols {gossypol} can inhibit dehydrogenase reactions and can reduce sperm count but cause low blood potassium and are poison.
Germ cells {gamete}| are haploid sperm or eggs.
Male and female gamete union {syngamy}| makes one somatic cell.
Corona radiata cells cover eggs, and hyaluronic acid holds them together. Many sperm attack corona radiata with enzymes, until one sperm breaks through {fertilization, process}|. Fertilizing sperm causes fertilization membrane formation, to block other sperm. Fertilized egg begins to divide. Eggs implant in uterus walls five to ten days after fertilization.
Women can be pregnant {maternity}.
after birth {post partum}|.
before birth {prenatal}|.
Cervix dilation and breaking water happen twelve hours before birth {birth, reproduction}| {nativity}. Fetus comes out head first, with face toward spine, taking 20 to 60 minutes. After cutting umbilical cord, umbilical arteries and veins close. Carbon-dioxide buildup causes first breath to start. At birth, heart blood flow changes direction. Head pressure can cause brain blood-vessel hemorrhage, and little breathing and low oxygen are dangers.
Cervix dilation and amnion breaking {breaking water}| happen twelve hours before birth.
Fetus comes out {parturition}| head first, with face toward spine, taking 20 to 60 minutes.
Surgically removing baby from uterus {Caesarean}| can be necessary.
Placenta {afterbirth}| expulsion happens 15 minutes after birth.
If oval window fails to close, blood is low in oxygen {blue baby}|.
Baby hearts have an opening {oval window, heart} between atria.
Birth weight can be less than 2.5 kilograms {premature birth}.
Female animals can have more than one baby in litters {multiparous}.
Female mammals can have one child each sexual period {uniparous}.
Twins {twin}| can be fraternal twins or identical twins.
Twins {fraternal twin} can come from two different eggs.
Twins {identical twin} can come from one egg that splits into two eggs.
Identical twins {Siamese twin} can share tissue.
People have external sex organs {genitals}|.
Fetal umbilical cords, cut after birth, leave remnants {navel}|.
Hairy skin {pubes}| is over pubic bone.
Primary sexual characteristics {sexual characteristic} are sexual organs. Secondary sexual characteristics are body-hair distribution, breast shapes, muscle sizes, and arm and leg carrying angles. Tertiary sexual characteristics are behaviors associated with being masculine and feminine. Male and female sex roles differ in different cultures.
Females {female reproductive organs} have ovaries, Graafian follicles, oogonia, Fallopian tubes, uterus, cervix, vagina, vulva, mons veneris, labia majora, labia minora, clitoris, and hymen.
Before birth, woman can lie in bed {lying-in}|.
Absorbent pads {sanitary napkin} can retain menstrual blood.
lesbianism {sapphism}.
female gonad {ovary, gonad}|.
Ovaries have follicles {Graafian follicle}|, which store oogonia. Ovaries produce eggs, one at a time in humans, and release mature ova into abdomen.
Ovum passes into tubes {oviduct} {Fallopian tube}|, for fertilization.
Oviducts lead to womb {uterus}|, where fertilized ovum attaches to wall and starts to develop.
uterus {womb}|.
Uteri have muscle rings {cervix}| at bottom openings.
From cervix, a tube {vagina}| leads to outside.
Thin membrane {hymen}| can cover vagina opening. Only three species have hymen.
hymen {maidenhead}.
At vagina opening are female sex organs {vulva}|.
Large flaps {labia}| {labia majora} with hair are around opening. Small flaps {labia minora} with no hair are over vagina.
A small penis-like organ {clitoris}| is in front of urethra.
Vulva top front {mons veneris} {mount of Venus} has fatty tissue covered by hair.
Ovaries have Graafian follicles, which store immature eggs {oogonium}.
Oogonia develop {oogenesis} to make oocytes.
Oogonia develop to make immature eggs {oocyte} {primary oocyte}.
If follicle matures, egg divides into main cell {secondary oocyte} and cell {polar body} with little cytoplasm.
One secondary oocyte divides into one large cell {ootid} and one polar body.
Polar bodies disintegrate, and ootid matures into egg cell {ovum} {ova}, with much yolk. Follicle cells kill bad eggs.
Cells {corona radiata} cover eggs. Hyaluronic acid carbohydrate holds cells together.
After sperm enters egg, membrane {fertilization membrane} forms, to block other sperm.
If egg has no fertilization, no egg implants, and uterus internal lining sloughs off {menstruation}| {menses}. Menstrual bleeding is greater in women than in other primates.
In most sexual animals, females have periods {estrus}| {heat, sex} {sexual readiness} {estrous cycle} when they are receptive to males, during which uterine glands secrete.
First-menstruation age {menarche}| is from 14 to 19 years old and decreases with city life, high-protein diet, and more exposure to males.
Menstruation typically ceases {menopause}| at 40 to 45 years old.
Females can have regular sex-receptive periods {rut, sex}|.
Males {male reproductive organs} have testis, seminiferous tubule, interstitial cell, epididymis, vas deferens, inguinal canal, prostate gland, and penis.
sperm and seminal fluid {semen}|.
Skin sacs {scrotum}| hold testes.
male gonads {testis, organ}|.
Testis makes sperm in tubules {seminiferous tubule}.
Testis makes hormones in cells {interstitial cell}.
Sperm pass into tubes {epididymis} for storage.
Tubes {vas deferens}| go through inguinal canal, over bladder, to urethra top.
Vas deferens goes through connective-tissue passageways between leg and pelvis {inguinal canal}|, over bladder, to urethra top.
At urethra, a gland {prostate gland}| {seminal vesicle} makes fluid and secretes it into vas deferens.
Urethra leads into fleshy organ {penis}|, which has erectile tissue.
bull penis {pizzle}.
Penis has three spongy-tissue {erectile tissue} columns that can fill with blood to become hard.
Glands {Cowper's gland} {Cowper gland} can secrete into urethra.
In males, penis tip {glans}| has orgasm.
Testes make small cells {sperm}| with nuclei and tails and many mitochondria. Male potency peaks in late adolescence. Sertoli cells kill bad sperm.
Fish spread sperm {milt}| over laid eggs.
Male germ cells develop to make spherical cells {spermatid} {spermatogenesis}. Spermatids mature into sperm having head with cell nucleus, neck with mitochondria for energy, and tail.
Spermatids mature into sperm, with enzyme pouches {acrosome} at tips. Acrosomes break corona radiata.
Lungs and throat breathe and exchange oxygen and carbon dioxide between air and blood {respiration, animal}.
People take 15 to 18 breaths per minute {breathing rate}. Volume rate is 0.5 liters per minute. Carotid-artery carotid sinus measures blood carbon dioxide and oxygen and sends signals to control breathing rate. Pons pneumotaxic center inhibits breathing after receiving signals from nerves that sense alveoli stretching. Medulla respiratory center sends excitatory signals along phrenic nerve to diaphragm. Pain increases breathing rate. Toxic or irritating gases inhibit breathing rate, at pharynx and larynx.
Total lung air {vital capacity}| is five liters.
chest {bosom}.
lungs, bronchi, and/or tracheae {bronchial}|.
about lungs {pulmonary}|.
Lung elasticity and chest-wall weight can push air out lungs {exhalation}|.
When diaphragm contracts and rib muscles relax, air cavity expands, pressure lowers, and lungs draw in air {inhalation}|.
Abdomen and rib muscles can force exhalation, especially in coughing {cough}| and sneezing.
Abdomen and rib muscles can force exhalation, especially in coughing and sneezing {sneeze}|.
Fish have sacs {air bladder}| that hold air for buoyancy.
Animals with tracheal respiratory systems have exoskeleton breathing pores {spiracle}|.
Air enters nose openings {external nares} {nostril}|.
After nostrils, air goes to open regions {nasal chamber} for smell and then goes to pharynx.
Above larynx, oral tract and nasal tract {vocal tract, throat}| produce speech.
Over larynx is a tissue flap {epiglottis}|.
Epiglottis has two epithelium folds {vocal cord}|, controlled by muscles that can vibrate air from 60 Hz to 350 Hz.
Birds can have thin muscles {syrinx}| that form vocal organ where trachea become bronchi.
Vocal cords are in upper middle larynx {glottis}|.
Air goes to throat {larynx}|. Larynx is behind adam's apple. In infants and vertebrates, flat tongue and high larynx allow simultaneous drinking and breathing, but adult humans have low larynx and downward curving tongue to make a sound chamber and allow non-nasal sounds. Early Homo sapiens [-400000] had tongue and larynx like modern people. Homo erectus had arching in larynx [-2000000], but Australopithecus had no arching and so only nasal sounds.
Larynx is behind cartilage {adam's apple}| at neck front.
Lung cavity {lung}| is closed chamber, at same pressure as air pressure.
Air goes to a tube {trachea, lung} {windpipe}| to lungs.
Windpipe branches into two tubes {bronchus}| {bronchi}, at first-rib level. Bronchi have smooth muscle and cilia, which send foreign particles back toward larynx. In response to irritation or stress, asthma can cause smooth muscle to contract uncontrollably.
Bronchi branch many times and end in open regions {air sac, lung}.
Air sacs have cavities {alveoli}| {alveolus} that have moist mucus walls surrounded by capillaries, which allow gas diffusion into and out of blood. They have air that is higher in carbon dioxide, lower in oxygen, warmer, and more humid, than outside air. Elastic connective tissue surrounds alveoli to aid contraction.
lung cavity and lung lining {pleura, lung}|.
When lung muscles {diaphragm, lung}| contract and rib muscles relax, air cavity expands, pressure lowers, and lungs draw in air for inhalation.
Humans have 206 bones {skeleton}|. Bones are 18% of human body weight. Skeletons have heads, trunks, arms, and legs.
facial features {physiognomy}|.
Sponges have small silicate or calcium-carbonate needles {spicule, skeleton}| that hold soft tissue.
Knobs {tubercle, bone}| can be in skin or on bones.
Bone junctions {joint, bone}| have cartilage covers filled with synovial fluid.
Joints have cartilage covers filled with fluid {synovial fluid}.
leg and loin {haunch}|.
arm or leg {extremity}|.
sole or palm {volar}|.
Ulnar nerve is near surface just above elbow back {funny bone}|.
Thumbs move by muscles {thenar} at palm-side thumb base.
Cowboys can have legs that curve to outside at knee {bowleg}|.
leg {gam}.
knee-to-ankle lower leg {shank, leg}|.
thick neck {bull neck}.
head and shoulders {bust}.
cheek {jowl}.
People can have long thin jaws {lantern jaw}| and/or jaws that stick out.
neck back {nape}|.
short flattened turned-up nose {pug nose}.
nostrils {schnozzle}.
neck back {scruff}.
Bodies have regions {crotch}| where two legs meet trunk.
Bodies have regions {groin, body}| where inner legs meet trunk.
Quadrupeds have hip regions {hindquarter}|.
about groin {inguinal}|.
hips, groin, and lower abdomen {loin, trunk}|.
Malnourished or old horses can have downward curving backbone {swayback}|.
In vertebrates, trunks have parts {thorax, body}| between necks and diaphragms. In arthropods, thorax is second or middle body segment, between head and abdomen. In insects, thorax holds wings and true legs.
horse back between shoulder blades {withers}|.
bone {os, bone}.
red or yellow bone insides {marrow, bone}.
finger or toe {digit, finger or toe}|.
finger {phalange}|.
palm {metacarpal}|.
palm {palmar}|.
wrist {carpal}|.
lower arm {radius}|.
lower arm {ulna}|.
Forearm and upper arm share joint {elbow}|.
upper arm {humerus}|.
foot {metatarsal}|.
sole {plantar}|.
Bones {talus, bone} {anklebone}| {astragalus, bone} can join tibia and fibula at ankle.
ankle {tarsal}.
Seven small bones are in ankle {tarsus}|.
Long hairs {fetlock}| can grow on back lower legs.
lower leg {fibula}|.
lower leg {tibia}|.
knee-to-ankle front lower leg {shin}|.
kneecap {patella}|.
upper leg {femur}|.
Head bone {skull}| has cranium and face bones. Face bones are maxilla, mandible bone, temporal bone, and orbit. Sinus is around nose-bridge.
skull {brainpan}|.
head top {pate}|.
Skull has a brain cover {cranium}| and face bones.
Skull parietal bones fuse at top {sagittal}|. Vertical plane goes through sagittal line.
Porous skull {sinus}| is around nose-bridge.
Skull base has wedge-shaped bone {sphenoid, bone}.
cheek bone {mandible, cheek bone}|.
jaws {maxilla}|.
eye socket {orbit, eye}|.
temples {temporal bone}|.
Scapula and clavicle {pectoral girdle}| hold arms.
sacrum and ilium {sacroiliac}|.
shoulder blades {scapula}|.
collarbone {clavicle}|.
Birds can fuse clavicles to form V-shaped bone {wishbone}| anterior to breastbone.
breastbone {sternum}|.
Sternum parts {gladiolus, bone} can be above xiphisternum.
Sternum parts {manubrium} can be above xiphisternum.
The smallest sternum parts {xiphoid} {xiphisternum} can be below gladiolus and manubrium.
Surrounding neural cord are 33 backbones {vertebra, spine}| {spine, vertebra}, which have flexible joints. Vertebrae are cervical, thoracic, lumbar, sacrum, and coccyx.
neck {cervical}|.
ribs {thoracic}|.
lower back {lumbar}|.
pelvis {sacrum}|.
lower tip {coccyx}|.
Ileus, ischium, and pubis fuse {pelvic girdle} {pelvis}| to hold legs.
middle back {ileus}|.
sides {ischium}|.
front {pubis}|.
ribs {rib cage}|.
Top seven rib pairs {true rib}| {sternal rib} attach to sternum.
Bottom five rib pairs {false rib}| do not attach to sternum. Top three false ribs connect to costal cartilage of rib above them.
Bottom two false ribs {floating rib}| {fluctuating rib} {vertebral rib} have no attachment in front.
Dogs and cats have fast running skeletons {digitigrade}.
People have slow running skeletons {plantigrade}.
Horses and deer have the fastest running skeletons {unguligrade}.
Rib cage, sternum, and vertebrae make main skeleton {axial skeleton}.
Arm and leg bones {appendicular skeleton} relate to appendages.
Human skeletons are inside body {endoskeleton}.
Body covering {skin}| has epidermis and dermis layers. Skin glands make oil and water and eliminate salt wastes. Most animals have drier skins than humans.
skin color
Skin color depends on epidermis yellow tinge, epidermis translucence, and skin-cell pigment amount and type: yellow, brown, or red. Melanin absorbs ultraviolet light and scavenges free radicals. Ultraviolet-B light causes melanocyte increase.
Chimpanzee skin is light colored, with pink skin at face, hands, and feet. Homo ergaster probably had little or no hair and had many more sweat glands.
High ultraviolet-A light reduces blood folic-acid concentration, needed for spermatogenesis and avoiding neural-tube defects. Ultraviolet-B light starts skin vitamin-D production. Vitamin D is for calcium absorption and for skeleton and immune-system development. Skin color balances these, with women having slightly lighter skin to absorb more calcium.
Spinal nerves receive sensory signals from skin areas {dermatome}.
Skin {glabrous skin}| can be hairless. Hairy skin is thinner than glabrous skin.
about tears {lacrimal}|.
Skin regulates heat loss by constricting or opening capillaries and regulating fluid {sweat}| production from glands {sweat gland}. 90% of heat loss is through skin. After temperature reaches 25 C, eccrine sweat glands affect temperature regulation. Anterior hypothalamus affects eccrine sweat glands.
Outer connective-tissue layers {epidermis, skin}| can have surface dead cells, which come from living and dividing cells below dead cells. Hairs and gland tubes go through epidermis.
Inner connective-tissue layers {dermis}| can have nerves, blood vessels, sense receptors, mechanoreceptors, sweat glands, oil glands, pigments, fat cells, and hair follicles.
Birds have contour feathers {penna}|. They also have down feathers and plumes.
Growing feathers {pinfeather}| have hard sheaths.
Bird wings or outer rear-wing edges contain main feathers {pinion feather}|.
Birds have feathers {plumage}.
Skin {foreskin}| {prepuce} can cover glans penis. Circumcision removes prepuce.
skin color {pigmentation}|.
Soft mounds {comb, bird}| can be on domesticated-fowl crowns.
Mounds {crest, bird}| can be on bird-head tops.
Finger and toe tips have fingerprints that typically have swirls {whorl}|.
Meissner's corpuscles lie in rows just below epidermis in fingertip surface ridges {dermal papillae}.
Collagen makes skin firm, and lack makes skin thin {wrinkle}. Elastin makes skin flexible. Glycosaminoglycans absorb water. Retinol, retin-A, or retinoin can prevent wrinkles by stimulating collagen production.
Wrinkles {crow's feet}| can be at outer eye corners.
Loose skin {dewlap}| can hang from neck fronts.
Skin {wattle}| can hang from chicken, turkey, and lizard neck or throat.
At birth, skin can have discoloration or unusual texture in small regions {birthmark}|.
People can have red birthmarks {strawberry mark}| on faces or scalps.
mole or birthmark {nevus}|.
Thick skin {scab, wound} can cover healed wounds.
Thick hard coverings {callus, skin}| can be over plant or animal wounds.
Gland cells {apocrine} can release hormones by shedding apex.
Exocrine glands {eccrine} include sweat glands.
Glands {merocrine} can secrete hormones without shedding cell parts.
Skin glands {sebaceous gland} can secrete sebum, which bacteria eat to make bad odors.
Sebaceous glands secrete carbohydrate {sebum}, which bacteria eat to make bad odors.
Modified sweat glands {mammary gland}| {teat} produce milk for infants.
Mammary glands produce sweet protein-rich and fat-rich liquid {milk}|, for infants.
Female cows, sheep, and goats have rear-underside bags {udder}| that contain mammary glands.
Heads have 100,000 hairs {hair, human}. Hairs grow several years, five inches a year. Follicles then become dormant, and hairs fall out. Later, new hair grows. Humans have less hair, because they have many more sweat glands with which to stay cool.
Hair holders {hair follicle}| have growing and non-growing phases. Dermal papilla are deep in dermis, organize hair follicles, and start hair matrix. Wnt signaling proteins induce hair follicles and control hair-growing cycle. Hairs fall out after bottom cells die.
region
Hairs have inner and outer sheathes. Hair follicles have attached muscles, which can form goosebumps, and nearby sebaceous glands.
curl
Flat follicles make curly hair.
color
Hair, fur, and feathers are dead skin cells. Pigments, air bubbles, and rough or smooth surfaces cause color.
Head hair {cowlick}| can grow in another direction than other hair.
Hair {forelock}| can grow from or fall over forehead. Horse manes typically have forelocks.
fur {pelt}.
short unshaven facial hair {stubble}.
woman's long hair {tress}.
Fingernails and toenails {nail, finger}| come from nailbeds.
Fingernail and toenail edges have hard skin {cuticle, fingernail}|. Annelids and other invertebrates have hard thin coverings.
Fingernails and toenails come from digit-tip skin-pad cells {nail bed}.
claw {talon, claw}|.
Animal (Animalia) groups {division, animals} are mostly invertebrates.
properties
Animals (Eumetazoa) (Metazoa) can have many eukaryotic cells. Animals digest internally {heterotrophic}. Animal cells have no cell walls. Animals can move. Embryos have blastula stage.
evolution
Animals evolved from eukaryotic collared flagellates {choanoflagellates}. Some sponges have choanocytes.
Choanoflagellates, fungi, and parasitic protists {opisthokonts} have posterior flagellum, as sperm do. Other eukaryotes have anterior flagellum or no flagellum.
Comb jellies were the first animals, and other animals evolved from them.
symmetry
Animals can have bilateral symmetry (Bilateria) or radial symmetry.
Placozoans have no symmetry.
Ctenophores and Cnidaria are radially symmetric. Echinoderms are radially symmetric.
symmetry: bilateral
Protostomes and deuterostomes are Bilateria.
Orthonectids (Orthonectida), rhombozoans (Rhombozoa), Myxozoa, Acoelomorpha, and cycliophora are Bilateria but are not protostomes or deuterostomes.
archenteron
Animals can open first {archenteron} at mouth (Protostomia) or first at anus (Deuterostomia).
coelom
Protostomes have mesoderm from gastrula interior {schizocoelous development}. Deuterostomes have mesoderm from endoderm invagination {enterocoelic pouching}.
protostomes
Protostomes are Lophotrochozoa, Trochozoa or Platyzoa, or Ecdysozoa.
Lophotrochozoa are segmented annelids worms and molluscs, plus arrow worms, bryozoans and ectoprocts and moss animals, entroprocts, gastrotrichs, lampshells, lophophorates, phoronids, proboscis worms, and sipunculan worms.
Trochozoa are flatworms and rotifers, plus spiny-headed worms, gnathostomulida, micrognathozoa, and cycliophora.
Ecdysozoa are ciliated protozoans, comb jellies or ctenophors, cnidarians or coelenterates, sponges, nematodes, and arthropods, plus gordian worms and horsehair worms, kinorhynchs, loriciferans, placozoa, priapulans, velvet worms, and water bears.
protostomes: evolution
From protostomes came Schizocoelia, Bryozoa, Parenchymia, and Gnathifera (Spiralia) and Gastrotricha, Introverta, and Cephaloryncha (Cycloneuralia).
Schizocoelia are Sipuncula and Articulata: Mollusca, Annelida, and Panarthropoda. Panarthropoda are Onchyophora, Tardigrada, and Arthopoda.
Bryozoa are Ectoprocta and Entoprocta.
Parenchymia are Nemertini and Platyhelminthes.
Gnathifera are Rotifera, Gnathostomulida, and Chaetognatha.
Introverta are Nematoda and Nematomorpha.
Cephaloryncha are Priapulida, Kinorhyncha, and Loricifera.
deuterostomes
Deuterostomes are echinoderms, acorn worms or hemichordates, and chordates, plus gnathostomulids.
deuterostomes: evolution
Echinodermata and Pterobranchia ancestors and Phoronida and Brachiopoda ancestors split.
Hemichordata ancestors and Echinodermata and Pterobranchia ancestors split.
Chordata ancestors and Hemichordata ancestors split.
invertebrates
Major invertebrates are protozoa (Protozoa), sponges (Porifera), jellyfish and corals (Coelenterata), hydroids (Hydroida), flatworms (Platyhelmintha), roundworms (Nematoda), earthworms (Annelida), insects and crustaceans (Arthropoda), clams (Mollusca), and starfish (Enchinodermata). Minor invertebrates are acorn worms, clictors, ctenophors, gastrotricha, lampshells, moss animals, phoronids, proboscis worms, rotifers, sipunculans, and velvet worms or onychophora.
vertebrates
Chordates include vertebrates. Vertebrates split from Ecdysozoa.
Animal classes {classification, animal} can depend on body organization.
cell differentiation
Animal cells differentiate into tissues and organs in patterns.
symmetry
Animals differ in symmetry: radial or axial.
body cavity
Animals differ in body cavity. Some animals have one cavity with mouth opening. Some animals have alimentary canal tube from mouth to anus, surrounded by coelom tube from mouth to anus.
segmentation
Animals differ in body-segment number and differentiation.
nervous system
Animals differ in body and nervous-system structure.
Number of repeated body structures {segmentation, body}| can differ.
Animals {animals} range from protozoa to humans. Animals can have internal or external skeletons.
Single-cell animals {protozoa}| {unicellular animal} (Protista) live in water. Protozoa have no cell walls or can have chitin cell walls. Protozoa can have specialized organelles, such as flagella, cilia, neurofibrils, vacuoles, and eyespots. Protozoa are motile. Protozoa require nutrients.
electrochemical
Protozoa have membrane ion channels and have membrane receptors for light, chemicals, and touch. They maintain electric-voltage differences across cell membranes, because salt and protein concentrations inside cells are different than outside.
Fresh-water protozoa fill vacuoles {contractile vacuole} with excess water and then eject water.
Protozoa {flagellate, protozoa}| (Flagellata) can be oval, have flagella, and have gullets or pseudopods. Euglena are flagellates. Sleeping-sickness protozoa are flagellates. Multicellular plants and marine metazoa evolved from flagellates.
Protozoa {flesh-like protozoa} (Sarcodina) can move by pseudopods. Amoebae eat by surrounding food with two pseudopods to make food vacuoles. Foraminifers secrete chalky shells with pores for pseudopods. Radiolarians secrete silica skeletons.
Protozoa {fresh-water protozoa} can live in fresh water. They fill contractile vacuoles with excess water and then eject water.
Protozoa {spore former} (Sporozoa) can be parasites, form spores {zoospore}, and have no cilia or flagella. Malaria plasmodium forms spores.
Protozoa {stentor} (Infusoria) can have trumpet shapes, for ciliated spiral feeding funnels.
Protozoa {sustorian} can move by cilia {mobile stage, protozoa} when young, attach to substrates by stalks when mature {sessile stage, protozoa}, and have cytoplasm tentacles that hold or pierce prey.
Protozoa {Toxoplasma} (Toxoplasma gondii) can sexually reproduce in cat species. Toxoplasma infect mammals and birds through transmission in feces, food animals, and soil. They form cysts {oocyst} that enter immune dendritic cells when in intestine.
Protozoa {vorticella} (Peritricha) can have cilia, have goblet-shaped bodies, and be retractile.
Protozoa (Ciliata) {ciliate}| can have cilia. Paramecia have oval shape, 2500 cilia, and two contractile vacuoles.
sensation
Paramecia have bilateral receptors, have neurofibril between basal bodies, and can sense if stimulus is from front or rear.
reproduction
Paramecia have one micronucleus for reproduction and one macronucleus for metabolism. Paramecia have eight mating types.
movement
Paramecia swim by spiraling forward. Touch, heat, cold, chemicals, and light change cilia beating and so swimming direction and speed, separately on each side. Paramecia cilia on both sides can go forward or reverse, or one side can go forward while other side does nothing.
Paramecia have holes {anal pore} in cell walls, from which waste leaves.
Paramecia have fixed tubes {gullet}| in cell walls, with vacuoles at base.
Near cell walls, paramecia have small bodies {trachocyst}, which send out filaments to hold prey.
Mating {conjugation, protozoa}| merges cytoplasms and exchanges nuclear material.
Bodies {kappa particle} divide independently and secrete ribonucleoprotein, which kills paramecia without kappa particles.
650 million years ago to 530 million years ago, animal phyla {invertebrate} evolved from protozoa.
types
Invertebrate types include anthozoans, crustaceans, ctenophors, echinoderms, insects, mollusks, stars, and worms. Lower invertebrates include ctenophors, coelenterates, flatworms, gastrotricha, proboscis worms, rotifers, roundworms, sipunculans, and sponges. Higher invertebrates include acorn worms, annelids, arthropods, clictors, lampshells, molluscs, moss animals, onychophora, phoronids, and starfish.
stimuli
Invertebrates sense chemical stimuli. Invertebrates can learn by touch but cannot distinguish shapes. Invertebrates have no joint receptors or proprioceptors, do not know muscle contraction or relaxation degree, and do not know body position. Invertebrates do not feel motivations, such as hunger or thirst.
learning
Invertebrates can learn to manipulate objects.
650 million years ago to 530 million years ago, early invertebrates {lower invertebrate} {marine invertebrate} {marine metazoa} had receptors, nerves, muscles, and glands. Enzyme, transmitter, hormone, messenger, and electrical-signal patterns coordinated behavior.
600 million years ago, body structures {coelom, invertebrate}| had a mesoderm cavity {schizocoelom} or had gut-cavity pouches {enterocoelom}.
Later invertebrates {Bilateria} were bilaterally symmetric [-590000000], with front and back and right and left. Bilateria include protostomes and deuterostomes. Body parts were in pairs, one right and one left {bilateral symmetry, body}, and body had front and back.
The first Bilateria (Urbilateria) included rounded flatworms {roundish flat worm}| (RFW). Chordates split from roundish flatworms 530 million years ago.
530 million years ago to 440 million years ago, later invertebrates {higher invertebrate} had ganglia, separate mouth and anus, muscular guts, developed circulatory systems, and coeloms. Chordates split from roundish flatworms 530 million years ago. For example, arthropods have nervous system on front, and vertebrates have nervous system on back. Both animal groups use same two genes for front and back, but chordate dorsal side is homologous with arthropod ventral side.
During Bilateria development, inner tube can open to outside head first {protostome}, not anus first as in deuterostomes. Protostomes include Trochozoa, Lophotrochozoa, and Ecdysozoa.
Trochozoa protostome worms (Rotifera) {rotifer} {wheel animal} (Monogononta) can be microscopic and aquatic. Rotifers have bladders, nervous systems, and flame cells. Anterior ends have spoked cilia rings.
Rotifera have same cell number {cell constant}. They cannot repair damage or grow after development finishes.
Rotifera have complete digestive tracts, including primitive stomachs {mastox}.
Rotifera have body cavity {pseudocoelom} between body wall and gut wall.
Trochozoa protostome bilaterally-symmetric worms {flatworm} (Platyhelminthes) can have mesoderm, have gastrovascular cavities, have muscular pharynx past mouth, and have reproductive organs.
front and back
Bodies have front and back. They keep back upward.
longitudinal
Bodies are longitudinal, with head, trunk, and tail, requiring body orientation. Head is body part that moves first, holds forward senses, and has mouth.
movement
Flatworms move by cilia, using muscular contraction. Muscles have opposing motions and have rhythms controlled by different cells.
nervous system
Flatworms have one brain ganglion with interconnected ventral nerves. Flatworms fused head ganglia to make brain.
Marine-flatworm brain bimodal neurons can habituate to vibration offset, using vibration-sensitive and tactile-sensitive interneurons. They can habituate to illumination offset, using light-sensitive interneurons.
senses
Flatworms have pigmented eyespot cells and can detect light, smell, and touch.
Flatworms secrete sugary substances {slime}| from gland cells.
Intestinal and blood flatworms have thick outer layers {cuticle, fluke}|.
Planaria excrete through tubes, from intestine to surface pores, which are lined with ciliated cells {flame cell}, to move water and waste out.
Ribbon worms have sections {proglottid} formed by budding behind head.
Male flukes have one slit {schistosome}|, into which smaller female fits.
One-centimeter-long intestinal and blood flatworms {fluke} look like planaria, have suckers, are blood and liver parasites, have no cilia, have thick cuticle, and have generation alternation.
life cycle
Flukes lay eggs, in animal urine or feces, which hatch into larvae {miricadia}. Larvae enter snails and change into different larvae {cercariae}, which can bore into skin, though they have no teeth, and then go to liver. In liver, male and female join {schistosomula} and enter blood to go to intestine and bladder. Adults have covering {tegument} that has few surface proteins but can bind human proteins. Adults can live 30 years.
Common flatworms {planaria}| {planarion} like still fresh water, can be parasites, respire by diffusion, and have tubes with flame cells to move water and waste out. For regeneration, smed-betacatenin-1 gene product indicates head, and Wnt gene product indicates tail.
Ribbon worms {ribbon worm} {tapeworm, animal}| can have suckers, or one ring of hooks, to attach to vertebrate intestines. Tapeworms are ribbon-like, have no mouth, have no digestive system, absorb food, and have proglottids.
Lophotrochozoa protostome worms {Gastrotricha} can be microscopic rotifer-like aquatic worms. Some species have no males but reproduce by parthenogenesis. Gastrotricha are cell constant.
Worms {sipunculan} are Lophotrochozoa.
Lophotrochozoa protostome worms {moss animal}| (Bryozoa) can have coelom and have carbonate or protein shells. Budding makes colonies grow, and sexual reproduction makes new colonies. Mouth and anus are at (Entoprocta) or near (Ectoprocta) lophophore. They have U-shaped digestive systems and have vase or tube shapes.
Moss animals have circular ridges with tentacles {lophophore} at top.
Moss animals form colonies {sea mat}, on seaweed.
Lophotrochozoa protostome worms {proboscis worm} (Nemertea) can be harmless, live in ocean, be 20 centimeters to 2 meters long, have narrow bodies, and have complete digestive tracts. Proboscis worms have circulatory systems, containing red blood cells, separate from digestive systems. They have two nerve ganglia connected by one nerve-fiber ring, with two long nerves down back. They have flame cells.
Proboscis worms have one long hollow muscular tube {proboscis}|, which everts from anterior end to get food.
Lophotrochozoa protostome worms {tube worm} {tubeworm} (Pogonophora) (Vestimentifera) can make tubes in which to live.
Sabellastarte longa tube worms {feather duster worm} have tentacles with small branches, on both central-axis sides.
Protostomes {clictor}| (Amphineura) can live in ocean and eat algae.
Lophotrochozoa protostomes {mollusc}| (Mollusca) {mollusk} can have hard carbonate shells. Molluscs are second largest phylum: oyster, clam, octopus, squid, snail, slug, and giant squid. Land snails are molluscs with lungs. Squid seem to feel pain. Molluscs have ganglia groups, each controlling one activity, in ring around gut. Snails have simple eyes. Squid and octopus have compound eyes. Other organ systems are like those in arthropods.
Molluscs have broad flat appendages {foot, mollusc} for creeping.
Molluscs have sheaths {mantle, mollusc} covering visceral mass and foot.
Pharynx has hard parts {radula}|, to break plants or shells. Oysters and clams have no radula.
Molluscs have body-organ masses {visceral mass}.
Bivalves have tubes {siphon, bivalve}| that send water out.
Eye microvilli can lie parallel, exhibit dichroism {rhabdom}, and detect polarized-light polarization plane.
Molluscs {bivalve}| (Pelecypoda) can have two shells, hinged at one side, no foot, one tube and valve that takes in water, and siphon tubes that send water out. Gills filter flowing water. Mucus carries food to mouth. Bivalves include oysters, clams, mussels, cockles, and scallops. Foot comes out of shell for movement. Clams and mussels burrow. Oysters do not move. Scallops move by clamping shells shut.
Mussels have sticky threads {byssus}.
Large clams {giant clam} {tridacna clam} can burrow.
Molluscs {cephalopod} (Cephalopoda) include squid, cuttlefish, octopus, and nautilus.
evolution
Cephalopods began 500,000,000 years ago.
anatomy
Head and foot combine. Eight tentacles in octopus, or ten tentacles in squid, have suckers. Two beaks are in mouth. Mantle can fill with water and eject water for jet propulsion movement after mantle receives signals from giant axons. Ink sac squirts to confuse enemies.
anatomy: shell
Cephalopods have little or no shell, as in squid and octopus, or chambered shells, as in nautilus. Nautilus secretes gas into chambers, to float.
anatomy: eye
Eyes develop from skin folds. Octopus rapidly learns visual and tactile discriminations by trial-and-error and can learn complex landscape, using same visual cues that people do. Nautilus eyes are pinholes, with statocysts and eye muscles. Other cephalopods have eyes with photoreceptors in microvilli at right angles, to detect plane-polarized light.
anatomy: brain
Statocysts can detect three-dimensional movement. A cephalopod brain region acts like cerebellum. Cephalopods have visual-memory brain structures. They have no myelin.
blood
Hemocyanin copper protein, which has low oxygen-carrying capacity, causes green blood.
Cephalopods {chambered nautilus} {nautilus} can be tropical and have shells. Nautilus has visual pits, which are indentations with pigmented cells and focus light like pinhole cameras.
Flat spiral-shelled, octopus-like sea animals {ammonite}| are extinct.
Molluscs {gastropod} {univalve} {gastropoda} include snail, limpet, abalone, and slug. During development, they twist so anus is above head. They have one heart, one gill, one kidney, one gonad, one valve, and one muscular foot.
Gastropods {abalone} can have large colorful shells.
Tropical gastropods {conch} can have spiral shells.
Small shelled gastropods can stick to tidal rocks {limpet}.
Large gastropods {triton} can have spiral shells.
Marine slugs and marine snails {nudibranch}| have no shells.
Sea snails {cone snail} can make peptide toxin {cone snail venom} {conantokin} that paralyzes fish or molluscs by affecting calcium-ion channels. Cone snails shoot out one tube with poison at end. 500 species have 50,000 different peptides.
Marine gastropods can have no shells {sea slug} {marine slug}.
Marine gastropods {pteropod} {sea snail, mollusc} {marine snail} are small.
Land nudibranchs {slug, mollusc} have no shells.
Nudibranchs {snail, mollusc} can live on land or in water. Land nudibranchs have shells.
Caterpillar-like worms (Onychophora) {velvet worm} are Ecdysozoa protostomes. Nervous, reproductive, and excretory systems are annelid-like. Circulatory and respiratory systems are arthropod-like.
Ecdysozoa protostomes {tardigrade} {water bear} can be 1.5-millimeters, live from oceans to mountains, and survive without water.
Ecdysozoa protostomes {roundworm} {nematode} can be microscopic, live on land and water, have pseudocoelom, have long cylindrical bodies, have cuticle, and have no cilia. Nematode parasites include hookworm, trichina worm, and ascaris worm. Roundworms have different sodium channels {roundworm sodium channel} in neurons than other phyla [Bargmann, 1998] [Niebur and Erdös, 1993]. Caenorhabditis elegans has reward-system dopamine neurons [Cherniak, 1995].
Roundworms {ascaris worm} can be intestinal parasites.
Worm {hookworm, worm} mouth hooks can stick to inner intestine walls.
Roundworms {trichina worm} can be intestinal parasites.
Jellyfish, hydra, sea anemones, and corals {coelenterate}| {cnidaria} are Ecdysozoa protostomes, live in ocean, and have radial symmetry.
digestion
They have mouths with tentacles that push food into mouth. Chemicals digest food in sacs, and then pseudopods from endoderm make food vacuoles.
tissues
Tissues are epithelial, connective, muscular, nervous, and reproductive.
senses
Hydra and jellyfish can sense mechanical, thermal, and chemical stimuli.
nervous system
Coelenterates were first animals to have neurons, synapses, and nerve nets, as well as specialized sense organs, but coelenterates have no organized interneurons or ganglia.
Both neural and non-neural cells transfer electrical signals by electrotonic coupling, with no chemical synapses.
In hydra, mechanical stimulation releases acetylcholine, epinephrine, norepinephrine, serotonin, and histamine transmitters from neurons, which discharge nematocysts.
classes
Classes are watery hydroids or hydra (Hydrozoa), flowery anemones and corals (Anthozoa), and bowl-shaped jellies (Scyphozoa). Corals and anemones are polyploid and stationary. Bases are downward, and tentacles and mouth are upward. Jellyfish are medusoids, swimming with tentacles and mouth downward.
colonies
Portuguese man-o'-wars bud on top of each other to make colonies.
Coelenterates have stinging cells {cnidocyte}, whose tips contain one nematocyst.
Cnidocyte tips contain one coiled stinger filament {nematocyst}, which can have poison, uncoil through cnidarian skin to puncture small animals, and entwine prey before digestion.
Coelenterates have one hollow sac with gelatin matrix {mesoglea} between endoderm and ectoderm.
Bacteria {zooanthellae} live in polyps and make oxygen used to make carbonates.
Anemones {sea anemone} {anemone, coral} {coral} use vertical partitions in hollow sac to make chambers to increase digestive surface, have gullet between mouth and hollow sac, and secrete carbonates. Anemones have one stalk with top stinging-tentacle ring. Corals make reefs. Living parts are on top, and sand and dead algae and coral are below.
Reef coral can look like brain cortex {brain coral} (Meandrina).
Coral colonies can have horny flexible branching axial skeletons {gorgonian} (Gorgonacea). Sea whips are gorgonians with long single stems. Sea fans have fan-shaped or tree-shaped skeletons.
Class Hydrozoaregenerate {hydra}| (order Siphonophora) attach to substrates by epidermal-cell discs at opposite end from mouth, and are one centimeter long. They have asexual budding. In stagnant water, high carbon dioxide causes mating types. Hydra have nerve nets. Nervous system governs tissue patterns and regeneration. Hydra polypeptide also is in bovine and human hypothalamus.
Blue hydra {Portuguese man-o'-war} float and have tentacles.
Scyphozoa {jellyfish}| have tentacles that move body through water and have thick mesoglea. Largest jellyfish is Cyanea, with 30-meter tentacles and four-meter diameter. Jellyfish have a statocyte with granules on hair cells. Marginal ganglia supply jellyfish rhythmic beats.
Jellyfish can have diploid sexual polyps and then have diploid asexual forms {medusa}|.
Jellyfish can have diploid sexual forms {polyp, jellyfish}| and then have diploid asexual medusa.
Sea walnuts and comb jellies {Ctenophora} are Ecdysozoa protostomes and live in ocean. They are similar to coelenterates but have only two tentacles. They have no stinging cells, move by cilia, can regenerate, and balance by a limestone-pebble otolith on a ciliated-nerve bed.
Jellyfish-like ctenophors {comb jelly} (class Tentaculata) (order Lobata) can be radially symmetric, be hermaphroditic, and have eight cilia rows.
Jellyfish-like ctenophors {sea walnut} {sea gooseberry} {Venus' girdle} can be plankton eaters.
Sponges (Porifera) {sponge, animal} are Ecdysozoa protostomes, live in ocean, are slimy, have bad smells, have porous skeletons, and have drab colors. Sponges have no body symmetry.
cells
Sponges have cellular differentiation for reproduction, food gathering, and skeleton production but no special tissues.
association
Sponges are ectomesenchymal-cell associations. Specialized intercellular junctions are within mesenchyme.
pores
Sponges take in water and food through skeleton pores. They force water out other pores. Pore epithelio-muscular cells and oscular sphincters regulate water flow.
Spindle-shaped and neuron-like mesenchymal cells are adjacent to pinacocytes and choanocytes. Large multipolar neuron-like cells are in collar below osculum. The neuron-like cells contain small, granular vesicles and norepinephrine, epinephrine, serotonin, acetylcholinesterase, and monoamine oxidase.
sensation
Sponges have cells that react to stimuli but no cell coordination.
Sponges have cells {collar cell} with flagella to move water in collar, below osculum.
Sponges have cells {amoebocyte} that move through matrix, collect food and water, secrete skeleton, and then become epidermal cells.
Sponges {calcarea} can have calcium-carbonate external skeletons.
Sponges {demospongia} can have spongin-protein external skeletons, to form soft sponges.
Sponges {glass sponge} can have silica external skeletons {hexactinellida}.
Ecdysozoa protostomes {arthropod} (Arthropoda) can have appendages.
segmentation
Species have numbers of body segments. All arthropods have same body plan, with six head segments {head, arthropod}, then middle segments {thorax, arthropod}, and then end segments {abdomen, arthropod}.
appendages
Arthropods have paired jointed appendages, used for swimming, walking, sperm transfer, or mouth parts.
coelom
Arthropods have true coelom, with reproductive organs.
digestion
Digestive system is annelid-like.
excretion
Excreting system can empty into digestive tract.
nervous system
Arthropod nervous systems are annelid-like, but ganglia fuse more in higher arthropods. Arthropods have ganglia groups, each controlling one activity, in ring around gut.
eyes
Compound eyes work like fish-eye lenses and show continuous scenes. Bees can process 300 images per second and can see ultraviolet but not reds.
pigments
Arthropods have hormones for pigmentation and reproduction.
behavior
Arthropods respond by kinesis, immobilization, orientation, or navigation. Arthropods have instincts, initiated by stimuli. Some arthropods have biological clocks. Arthropods can learn to run mazes. Arthropods can measure lengths and angles, for honeycombs and spider webs.
Arthropod circulatory systems have blood cavities {hemocoel} and pumping organs.
Arthropods have outside skeletons {exoskeleton}, with inner chitin layer, middle rigid layer, and outer waxy layer.
Arachnids and horseshoe crabs have head, thorax, and abdomen fused together {chelicerate}.
Crustaceans {crustacean}| (Crustacea) are aquatic and live mostly in ocean. They have one mandible pair, have two maxillae pairs, respire by gills, and molt. They have compound eyes. They have two antenna pairs. Shrimp, crayfish, lobster, and crab have ten legs and can have carapace. Barnacles, water fleas, and krill have six or eight legs. Copilia has two eye lenses, for close vision. Vargula firefleas make intense light.
Crustaceans have eyes {compound eye}| with similar parts.
Crustaceans respire by membranes {gill, crustacean}| in contact with flowing water in association with blood vessels.
Crustaceans have upper and lower jaws {mandible, crustacean}|.
Crustaceans have two cheek-part pairs {maxillae}|.
Small tidal filter feeders {barnacle} have free-swimming larvae. Cirripedia adults have hard shells and attach to rocks.
Trilobites {trilobite} (Trilobita) are extinct, lived at ocean bottom, had three larval periods, had three longitudinal lobes, and were 60% of all animals during Ordovician. They began in Pre-Cambrian and lasted until Permian, 300,000,000 years. They most closely relate to horseshoe crab. Trilobites swam, crawled, and burrowed.
parts
They had head {cephalon}, thorax, and tail {pygidium}, each with side lobes {pleura, trilobite} and central lobe {axis, trilobite}. Cephalon has top central plate {glabella} with side shells {fixed cheek}, making structure {cranidium}. Segments had two arthropod jointed legs, which branched to have gill surface and walking leg. Two antennae were on head.
The most important crustaceans have ten legs {decapoda} {decapod} and can have carapace. They include shrimp, crayfish, lobster, and crab.
Decapoda can have chitin {carapace}| with calcium salts.
Warm fresh-water decapods {crayfish} {crawfish} (Astacus) have claws.
Small long-tail decapods {shrimp, crustacean} (Natantia) have fused head and thorax and segmented abdomen.
Decapods {prawn, crustacean} can be large shrimp.
Baleen whales eat euphausiacea crustaceans {krill}.
Large decapods {lobster, crustacean} have claws. Homaridae have eye stalks {eyestalk}. Homaridae have astaxanthin pigment, which binds to beta-crusta-cyanin protein and is insoluble.
Decapods {spiny lobster} (Palinuridaecan) can have no claws and spiny carapace.
Simple crabs (Merostomata) {crab} have ten legs, have pinching claws, and are chelicerates. Crabs include king crab. Horseshoe-crab eyes can see contrasts and use reflection. Blue-crab males have blue claws. Callinectes sapidus are soft-shell swimming crabs.
Burrowing crabs {fiddler crab} can have males with one large claw and one small claw.
Large crustaceans {horseshoe crab} have hard tails.
Alaska king crab or Japanese king crab {king crab} has claw width up to 3 meters, weighs up to 5 kilograms, and is white inside.
Insects {insect}| (Insecta) have six legs, have up to eleven abdomen segments, have no legs on abdomen, have tracheae, and have simple or compound eyes. Insects can have a small connection between first and second abdomen segments. Insects can have diapause. Insects can form social colonies.
types
Main orders are bees and wasps and ants (Hymenoptera), butterflies (Lepidoptera), and beetles (Coleoptera). Insects are the largest class, with 25 orders, and include cricket, katydid, grasshopper, walking stick or mantis, flea, firefly, ladybug, ant, honeybee, wasp, yellow jacket, hornet, bee, beetle, moth, butterfly, and termite.
Hymenoptera females have one tube {ovipositor}, which can also sting, to insert eggs into hosts.
Crab, bee, and fly have 1000 photoreceptors {ommatidia}, connected to inhibitory retina.
Bees, ants, and termites have associated individuals {colony, arthropod}|, with one female queen.
ants
Bees and ants have male drones. Ants can take slaves. Sterile female worker ants feed soldiers, king or drones, and queen.
bees
Queen bee lays fertilized eggs to make workers, soldiers, and new queen. Workers receive no special food. Soldiers receive royal jelly and then nectar and pollen. New queen receives only royal jelly. Queen lays unfertilized eggs to make king or drones. Queen and king or drones have wings, to fly away to start new colonies. Oldest worker bees get water, pollen, and nectar. Middle-age bees secrete wax, clean up, store food, and guard hive. Young worker bees feed larvae and prepare hexagonal cells for eggs. Bees can recognize colors, except reds. Bees do circling and wagging dances, which show food source angle, direction, distance, and amount.
termites
Termites have one male king. Termites that build mud mounds follow rules about when to add and when to remove mud.
Moths, bees, butterflies, and flies can have large changes between developmental stages {metamorphosis}|. In first metamorphosis stage, egg develops. Then larva hatches from egg, crawls, eats, and looks worm-like. Larva is caterpillar for moths and butterflies, maggot for flies, and grub for bees. Larva molts several times, then makes pupa. Adult breaks pupa cocoon, pumps blood into folded parts, and secretes chitin to harden exoskeleton.
Chilling causes secretion of hormone {prothoracicotropic hormone} that induces prothoracic glands to secrete ecdysone.
Chilling secretes prothoracicotropic hormone, which induces glands {prothoracic gland} to secrete ecdysone.
Prothoracic gland secretes growth and differentiation hormone {ecdysone}, which produces molting fluid.
Metamorphosis hormones {juvenile hormone} can prevent pupa formation and allow molting.
Bee larva {grub}| molts several times.
Fly larva {maggot}| molts several times.
Moth and butterfly larva {caterpillar}| {larva} molts several times.
Last moth and butterfly larval stage is cocoon {pupa}| {chrysalis}, which has molting.
Collapsed folded adults {disc} can develop from special larva egg cells.
Insects can have dormant periods {diapause}| as adults.
Lepidoptera undergo metamorphosis through egg, larva, pupa, and adult {imago}.
Grasshoppers and other insects can have larval stages {molt}|, in which epidermal glands make enzyme that breaks down inside cuticle. Then folded inner cuticle grows. Then water or air intake breaks hard outer cuticle. Then new cuticle hardens, using calcium carbonate.
Cell groups {x organ} and sinus gland have hormone that prevents molting.
x organ has axon-tip bundles {sinus gland} that have hormone that prevents molting.
Flying {flying insect}| can be hovering, flapping, or flipping.
wing
In wing stroke, leading-edge vortex above wing increases lift, because vortex does not detach {delayed stall}. At stroke end, wing rotates to give lift {rotational lift}, like backspin on rising fastballs. At upstroke, wing goes through downstroke wake at orientation that provides lift {wake capture}. Fly hind wings act like gyroscopes to sense body orientation. Flies beat wings at 200 beats per second, under muscle-tension control.
metabolism
Flying is four times more efficient than ground locomotion but uses ten times more energy. Flying muscles have highest metabolic rates. Air has higher viscosity-to-density ratio and so is more viscous than water kinetically.
Flying can involve flapping {flapping} wings up and down.
Flying can involve moving wings in figure eights, with body horizontal {flipping}.
Flying {hovering}| can use horizontal-wing movements and twists with body vertical.
Insects {arachnid}| (Arachnida) can respire by tracheae or book lungs, have simple eyes, have poison claws on head, have eight legs, have no antenna, be carnivores, and be chelicerates. Spider, scorpion, tick, and mite are arachnids.
Arachnids respire by tracheae or by membranes that look like books {book lung}.
Large black spiders {black widow spider} have neurotoxic poison.
Mites {chigger} can be skin infesting.
Arachnids {daddy longlegs} can have long legs and small bodies.
European water mites {diving spider} (Argyoneta aquatica) can make underwater webs.
Spiders {jumping spider} can have 2000 retina receptors but no ganglion cells. Main eye has fovea with 30 cells 10 arc-minutes apart. Main eyes scan objects from one side to another for 1 to 2 seconds. If no recognition, scan repeats. Main eye can rotate 25 degrees for 5 to 15 seconds to learn line orientation. Objects detected are other jumping spiders, small and moving prey, big and coming close predator, or objects to investigate further. Other eyes detect movement and initiate saccades, based on angle between stimulus and body axis. Other eyes take 100 milliseconds to check if saccade succeeds.
Arachnids {mite, arthropod} (Acarina) can be small.
Arachnids {scorpion} can have high curving tails with poisonous sting.
Arachnids {spider, insect} can have eight legs and two body parts and make webs.
Large fuzzy spiders {tarantula} can bite.
Arachnids {tick} can be blood-sucking.
Black widow spider, Australian red-back widow spider, and brown widow spider {widow spider} (Latrodectus) have neurotoxic poisons.
Insects {centipede} (Chilopoda) can have segment leg pairs, be fast carnivores, live on land, have poison claws behind head, respire by trachea, and have flattened bodies.
Centipedes and millipedes can have simple eyes {ocellus}.
Centipedes respire by air tubes {trachea, centipede}.
Caterpillars {inchworm} {measuring worm} can raise middle then stretch out to move.
Small free-swimming fresh-water copepods {water flea} (Cladocera) {daphnid} can have large median eyes, pear-shaped bodies, and long antennae.
Insects {copepod} can have single-channel scanning eyes, like scanning beams in television cameras or electron beams in TV tubes. Copepods are in plankton.
Insects (Coleoptera) {beetle}| can have two wing pairs, two wing covers, and two thin wings. Horny front wings cover back wings, at rest. Mouth is for biting. Stenocara condenses fog on its back and tilts head down to receive water.
Beetles {boll weevil} can live and hatch in cotton balls.
Insects {click beetle} (Elateridae) can click when springing from back to feet.
Shiny green beetles {Japanese beetle} can eat plants.
Beetles {june beetle} can be large, be brown, live in North America, and eat leaves. Larvae feed on grass roots.
Small red beetles {ladybug} can have black spots.
Tenebrio molitor {darkling beetle} {mealworm} {meal worm} larvae are slender, have hard bodies, and eat grains and cereals.
large black beetle {scarab beetle}.
Beetles {stinkbug} can have bad smell.
Smooth oval-body beetles {water beetle} (Dytiscidae) have flattened hind legs for swimming.
Beetles {weevil} (Curculionidae) can eat plants. Snouts curve down.
Insects {ear wig} (Dermaptera) can have rear pincers.
Roaches {roach} (Dictyoptera) include cockroach.
Roaches {cockroach} can have organs {cerci} sensitive to vibration.
louse {cootie} (Blattodea) (Blattaria).
Insects {millipede} (Diplopoda) can have many fused double segments with short legs, be slow, live on land, have cylindrical bodies, be herbivores, and have ocellus.
Insects {fly} (Diptera) can have vision detectors for looming, moving patches, angles, and velocities. In scorpions and flies, membrane lens forms over visual pit to focus light.
Mosquitos {anopheles mosquito} (Culicidae) can transmit malaria.
Flies {blue bottle fly} can be shiny and blue.
Flies {dragon fly} can be large, with four large wings.
Nocturnal flies {firefly} can make light.
Flies {fruitfly} (Drosophila) can have red eyes. Attention affects neurons [Heisenberg and Wolf, 1984] [Tang and Guo, 2001] [van Swinderen and Greenspan, 2003]. Fruitflies can learn by trace or delay conditioning [Tully and Quinn, 1985]. Fruitflies have halteres balancing wings. Larvae eat fruit.
Fireflies have larvae {glowworm}.
Large flies {horsefly} have females that suck blood.
Black flies {housefly} can be small.
firefly {lightning bug}.
Female flies {mosquito} can suck blood.
African flies {tsetse fly} can suck blood and transmit sleeping sickness.
Insects {aphid} (Hemiptera) can be plant-sap suckers.
wingless bloodsucker {bedbug} (Cimicidae).
small winged insect {gnat}.
gnat-like Chironomidae fly or Ceratopogonidae dipteran {midge}.
Insects {scale insect} can make wax scales on plants.
Water boatman and backswimmers {water bug} are large and have piercing and sucking mouth parts.
Fresh-water water bugs {water strider} (Gerridae) (Veliidae) can have long thin legs.
Large insects {cicada} (Homoptera) can make high sounds.
Nymphs {spittlebug} (Cercopidae) can be in bubbly white clumps on plants.
Ants, bees, wasps, and sawflies {Hymenoptera} have two wing pairs, front larger than back. They undergo complete metamorphosis. Females have one ovipositor, which can also sting.
Ants (Formicidae), bees (Apoidea), and wasps (Vespidae) form a suborder {Apocrita}, whose animals have wasp waists.
Female wasps {wasp} can remember their hole states and positions, for two or three days.
large wasp {hornet}.
Midwest and west USA wasp {mud dauber wasp} builds mud nests.
Small wasps {yellow jacket} can be yellow and black.
Insects {ant, insect} (Formicidae) can be wingless and live in colonies. Saharan desert ant (Cataglyphis fortis) tells direction by light polarization and tells distance by counting number of steps and adjusting for weight. Ants take dead ants out of the nest {necrophoresis}. Dolichodial and iridomyrmecin decrease after death. Other ants can detect ant dolichodial and iridomyrmecin and so do not take ants out of the nest.
Small red ants {Amazon ant} can take slaves.
Ants {army ant} can travel together and attack insects.
Red ants {red ant} can be medium size.
Sterile females {soldier ant} can have heavy jaws and armor.
sterile females {worker ant}.
Insects {bee} can beat wings at 200 beats per second, under muscle-tension control. Bees can calculate orientation over ground by angle Sun makes with horizon at highest point {azimuth system}, which varies over year.
Bees and ants have males {drone, arthropod}|.
Bombus bees {bumblebee} loudly vibrate wings and thorax to shake pollen from flower anthers {buzz pollination}. They push pollen along body into leg pollen holders.
Bees {honeybee} can make honey in colonies in hives. Honeybees do not vibrate wings or body. Colonies are dying at higher percentage now {colony collapse disorder}.
Social insects {termite} (Isoptera) can eat wood.
Insects {Lepidoptera} can have two wing pairs covered with scales. Mouth is for sucking. They undergo metamorphosis through egg, caterpillar, chrysalis, and adult. Lepidoptera include butterflies, moths, and skippers.
Lepidoptera {moth, insect} can hold wings flat while resting and fly at night. Moths have feathery feelers, live on land, have two antennae, and have two wing pairs raised by vertical muscle contraction pulling tergum down and lowered by longitudinal muscle contraction at 8 to 75 beats per second, under nerve control.
Large light-green American moths {luna moth} can have hind wings with tails and forewings with yellow crescents.
Moths {noctuid moth} can be pale and medium-size.
Noctuid-moth larvae {army worm} swarm and eat grass and grain.
Lepidoptera {butterfly} can hold wings straight up while resting and fly only by day. Butterflies have smooth feelers with end knobs, live on land, and have two antennae. Bicyclus-anyana adults have color if born in rainy season but are gray if born in dry season.
thorax upper-surface plate {tergum}.
Tropical butterflies {swallowtail} (Papilionidae) can have three leg pairs and tailed wings.
Insects {mantis} (Mantodea) can have big forelimbs, like grasshoppers.
Insects {cricket} (Orthoptera) can leap and make high sounds.
Insects {grasshopper} can leap, have long hind legs, and chirp.
Green insects can make shrill sounds {katydid}.
cicada or swarming grasshopper {locust, arthropod}.
Insects {louse} (Pediculidae) (Phthiraptera) can be small and wingless.
louse parasitic insect eggs or young {nit}.
Insects {flea} (Siphonaptera) can be small, wingless, and blood sucking.
Caribbean fleas {chigoe} can be skin infesting.
Bristletail (Zygentoma) and firebrat (Thysanura) {silverfish} are wingless and silver and eat book and cloth starch.
Ecdysozoa protostomes {annelid}| are higher worms.
skin
Epidermis secretes mucus and cuticle, to prevent water loss.
movement
Circular and longitudinal muscles cause movement by stretching and contracting.
digestion
Annelids have schizocoelom. Annelids have mouth, pharynx, esophagus, crop, gizzard, and straight intestine.
blood
The two main blood vessels connect by pairs of muscular tubes acting like hearts. Vessels have capillaries.
nervous system
Head has stimulating ganglion and inhibiting ganglion. Segments have one small ganglion each. Reflex arcs run from sense cells to muscle sets. Neurons have few dendrites, no myelination, few Schwann cells, no oligodendroglia, no astrocytes, no microglia, no nerve tracts, no inhibitory surrounds in receptor fields, no feedback circuits in receptor fields, and no amacrine cells in receptor fields. Neurons have basic neurotransmitters, ion channels, excitability, synaptic potentials, pacemakers, and rhythmic voltage patterns, with frequency twice as high as in vertebrates.
senses
Annelids can have eyes and antenna. Membranes cover visual pits to protect photoreceptor cells.
pigment
Earthworms have pigmented skin cells.
pain
Worms feel no pain.
Segments have two strong short hairs {bristle, hair}| on epidermis.
Annelids have 100 similar parts {segment, worm} {segmentation, worm}|, with pairs separated by septa.
Walls {septum, segments} separate annelid segment pairs.
In septa, blood vessels surround ciliated-funnel pairs {nephridium}. Tubes lead from nephridia to surface to carry away wastes.
Tubes from nephridia have enlargements {bladder, annelid}| in centers.
Annelid stomachs have one storage part {crop, stomach}| and one gizzard.
Annelid stomachs have one crop and one digesting part {gizzard}|.
Testes and ovaries are in same animal {hermaphrodite}| and have tubes leading to surface. Two worms press together and deposit sperm in each other.
Worms form coverings {cocoon}| from bottom to head, in which they first deposit eggs and then sperm.
Annelids {earthworm} {oligochaeta} {night crawler} {worm, animal} can have few bristles and live in soil and fresh water.
Annelids {leech} (Hirudinia) can have suckers at ends to draw blood from vertebrates, use anticoagulant, and have no bristles.
Marine annelids {marine annelid} {archiannelida} can be non-segmented marine worms without bristles.
Ocean annelids {ocean annelid} {polychaeta} {polychaetes} can have many bristles and separate sexes, which release gametes into water by seasonal, lunar, and diurnal cycles.
During Bilateria development, inner tube can open to outside anus first {deuterostome}, not head first as in protostomes.
Deuterostome worms {lampshell} (Brachiopoda) can live in ocean and have coelom. Lampshells have a top carbonate shell and a bottom carbonate shell. Lampshells are oldest genus with living members. Brachiopoda and Phoronida share common ancestor, from which Enchinodermata ancestors split.
Deuterostome worms {phoronid} (Phoronida) and Brachiopoda have a common ancestor, from which Enchinodermata ancestors split.
Starfish, sea star, sea urchin, sea cucumber, serpent star, and sea lily {starfish} {echinoderm} (Enchinodermata) are deuterostomes, live in ocean, have radial symmetry, have central disc, have five to twenty arms, and have mouth on underside. Starfish have no ganglia and no circulatory, respiratory, or excreting system. Brachiopoda and Phoronida share common ancestor, from which Enchinodermata ancestors split. Hemichordata ancestors and Echinodermata and Pterobranchia ancestors split.
Starfish can pump water {water vascular system}, to move and to open prey.
Enchinoderms {sand dollar} (Clypeasteroida) (superorder Gnathostomata) (class Echinoidea) can be flat and circular, have spines, and have five-star patterns. They relate to sea stars, sea urchins, and sea cucumbers.
Enchinoderms {sea cucumber} (Holothuroidea) can have cucumber shapes, flexible bodies, and tentacles.
Enchinoderms {sea urchin} (Echinus) (class Echinoidea) can have shells, long spines, tube feet, and five movable mouth parts.
Enchinoderms {sea star} can have star shape and five or more arms with tube feet.
Euryale, Astrophyton, and Gorgonocephalus {basket star} have slender branched crossed arms.
Worms {acorn worm}| (Enteropneusta) can live at ocean bottom, have proboscis attached to collar at cylindrical body top, and eat organic matter. Hemichordata ancestors and Echinodermata and Pterobranchia ancestors split. Chordata ancestors and Hemichordata ancestors split.
Prechordates {stem chordate} had notochord in both larval and adult stages, allowing muscle attachment, providing long body axis, and affecting reproduction.
germ layers
Prechordate embryos had three cell layers. Endoderm is inner tube, mesoderm is between, and ectoderm is outer tube. Ectoderm becomes senses, nerves, and outer skin. Mesoderm becomes muscles and glands. Endoderm becomes digestive tract.
coelom
Prechordates had tube-shaped body structures, with digestive tube inside main tube.
deuterostome
During development, inner tube opens to outside anus first.
head and tail
Having coelom makes longitudinal bodies, from which head, trunk, and tail can separately evolve. Head holds central ganglia and mouth.
bilateral symmetry
Body parts and appendages have pairs, one right and one left. Body also has front and back. Bilateral symmetry [-590000000] resulted from having coeloms.
segmentation
Prechordates had repeated body structures, allowing different lengths and requiring coordination among body segments. Segments can vary independently.
development stages
Prechordates had streamlined larvae with cilia for swimming in mobile stage. Adult sessile stage did not move. Prechordate ciliated larvae evolved to become stem chordates.
bone
Stem chordates calcified tissue to make bone, allowing better muscle attachment, more shapes, and more textures.
respiration
Stem chordates had external respiration by gills, allowing efficient oxygen uptake and carbon-dioxide removal from blood. Body-side gill slit openings allowed water to flow into mouth and through gills, resulting in better respiration.
nervous system
Prechordates had main head ganglion, with peripheral nerves to tail. Head ganglion provided unified control for all body segments and allowed swimming, burrowing, and defense. Stem chordates had dorsal hollow nerve, so all nerves have same pathway from head to periphery. Cerebrospinal fluid was in dorsal hollow nerve. Nerves were bilateral sense and motor paths. Interneurons coordinated neurons.
hormones
Hormones from glands affect neurons and other tissues.
Chordates {chordate}| (Chordata) are deuterostomes and have bilateral symmetry.
types
Amphioxus is a living chordate, has no jaw, is flat, and is small. Pikaia was an ancient chordate [Bone, 1979].
evolution
Hemichordata ancestors and Echinodermata and Pterobranchia ancestors split. Chordata ancestors and Hemichordata ancestors split. Chordates developed from prechordate larval forms.
notochord
Early chordates had one firm cartilage segmented rod down back along body long axis, allowing increased swimming efficiency by providing places for muscle attachment. Adult notochords allowed reproductive-method changes.
external respiration
Early chordates had paired pharyngeal gill slits. Side openings allowed greater water flow into mouth, over gills, and out body. Blood oxygen uptake and carbon-dioxide removal became more efficient with gills.
filter feeding
Skin calcification made dermal bone that allowed structures for catching small organisms in water flowing into mouth. Filter feeding gathered more food and calcium.
nervous system
Dorsal hollow nerve lay along back under notochord, from periphery to head, and had sense and motor pathways. Cerebrospinal fluid formed in middle.
brain
Head ganglion unified control over all body segments and other ganglia, coordinating sense input and motor output. Brain allowed better swimming, burrowing, and defense and more coordinated behavior. Eye, pineal gland, hypothalamus, and hindbrain began in chordates. Chordates had serotonin neurons, which later evolved to brainstem.
senses
Sense cells detected motions and stationary patterns.
Skin-tissue calcification {dermal bone, chordate} allows structures for filter feeding.
Dermal bone allows structures for catching small organisms in water flowing through mouth {filter feeding}, which gathers more calcium to make bone and allows more energy and larger sizes.
Chordates have flexible straight cartilage {notochord}| down back.
Stem chordates have head as unique body segment, whose ganglion {main ganglion} provides unified control for all body segments and allows swimming, burrowing, and defense.
Stem chordates have a tube of nerves down back {dorsal hollow nerve}, so all nerves have same pathway from head to periphery.
Prechordates have ciliated larvae that swim {mobile stage, prechordate}.
Prechordates have mobile larval stage that has movable hairs {ciliated larvae} and swims.
Prechordate adult stage {sessile stage, prechordate} does not move and evolved little.
Stem chordates have external respiration {gill, chordate}|, allowing efficient oxygen uptake into blood and carbon-dioxide removal from blood.
Body-side openings {gill slit}| allow water to flow into mouth and through gills, for better respiration.
Gills allow blood and water to exchange oxygen and carbon dioxide {external respiration} efficiently.
Embryonic bodies have endoderm alimentary canal within ectoderm tube {coelom, chordate}|, with mesoderm between tubes.
Ectoderm coelom surrounds endoderm tube from mouth to anus {alimentary canal}|, with mesoderm between tubes, allowing better digestion.
Chordates {cephalochordate} (Cephalochordata) can have body segments, be small, be fish-like, strain seawater for food, and have no brain. Adults have chordate characteristics.
540 million years ago, later chordates {prevertebrate} calcified skin {dermal bone, skin} and formed cranium bone around brain, allowing more muscle-attachment sites and better protection. Prevertebrates had structures for filter feeding.
Chordates {tunicate}| {sea squirt} (Urochordata) can live in tropical oceans, be sessile or floating, and have translucent cellulose covers, with hole for incurrent siphon and hole for excurrent siphon. They filter-feed to catch phytoplankton. They can bud. Larvae have chordate characteristics, but adults have gill slits. Vertebrates evolved from tunicate larvae.
Floating tunicates {salp} can have barrel shapes and live in colonies, making tube strings. Salp feces sink to bottom, carrying phytoplankton carbon molecules from carbon dioxide.
Swimming tunicates {larvacean} {apendicularian} (Larvacea) can have oval bodies, movable tails, and notochords. Every few hours, they make 2-centimeter-diameter gelatin mass around body, in which they trap plankton. Mucous mass sinks to bottom, carrying phytoplankton carbon molecules from carbon dioxide. Larvaceans make no buds, only use sexual reproduction, and are mostly hermaphrodites. Sperm release first. Breaking body wall releases eggs and causes death.
Tunicates have translucent cellulose covers {tunic, tunicate}, with hole for incurrent siphon and hole for excurrent siphon.
530 million years ago, chordates {vertebrate} developed cartilage or bone notochords, allowing more muscle attachment.
skeleton
Vertebrates have internal cartilage or bone skeletons, to replace or reinforce notochord. They have backbone segments {vertebra, vertebrate}. They have one cranium. Distinct trunks are between heads and tails.
circulation
Closed circulatory systems use blood vessels.
pharynx
Pharynx separates digestion pathway from respiratory pathway, making both more efficient and independent.
skin
Two-layer skin has epidermis and dermis.
communication
All vertebrates communicate using signs, such as gestures, odors, calls, cries, songs, and dances.
nervous system
Vertebrate brain has hindbrain, midbrain, and forebrain. Hindbrain has ganglia for sleep, wakefulness, and sense information analysis, and cerebellum for coordinating motor behavior. Midbrain has ganglia for sense information analysis. Forebrain has occipital lobe for visual information analysis, temporal lobe for hearing and equilibrium information analysis, parietal lobe for touch and temperature information analysis and motor output, and frontal lobe for smell information analysis.
senses
Eyes develop from brain. Ears are for balance in lower vertebrates and for sound in higher vertebrates.
evolution
Early vertebrate was Sacabambaspis [-450000000].
evolution: superclasses
Superclass is fish (Pisces), with highly vascular gills. Superclass is legged vertebrates (Tetrapoda), with four appendages, including amphibians (Amphibia), reptiles (Reptilia), birds (Aves), and mammals (Mammalia).
Lower vertebrates {fish} (Pisces) have one heart with one vena cava entering auricle, one auricle connecting to ventricle, and one aorta leaving ventricle. Fish have vascular gills. They have scales. Females lay eggs in water that males cover with sperm. Fish have ears. They are streamlined. They move by swishing tail right and left. They steer with fins. Fish include jawless fish (Agnatha), extinct jawed fish (Placodermi), cartilaginous fish (Chondrichthyes), and bony fish (Osteichthyes).
Fish have canals and openings {lateral line} running from head to tail on both sides, to perceive pressure changes and water-flow changes.
Some jawed bony fish had stump fins {lobefin}|, allowing crawling onto shore. Lobefins later became appendages.
Some bony fish make groups {school, fish}|, which concentrate breeding stock, minimize losses to predators, confuse predators, increase food or danger perception, and move together by sight and lateral line.
Fish have sacs {swim bladder}| that can fill with secreted gas for buoyancy.
Fish have gill slits covered by hard flaps {operculum}.
Fish have gill and neck bones {opercular bone, fish}.
Some bony fish had nasal passages {nares}| with internal openings into windpipe inside body, rather than externally to water. Nares allowed more-efficient breathing, moist and filtered air, and alternative air path through mouth, not just nose.
Some jawed bony fish had nasal passages inside to lungs {internal nares}, allowing more efficient breathing.
Agnatha {jawless fish} were first fish.
size
Jawless fish are mostly small but can be up to one meter long.
body
Jawless fish have cylindrical bodies, with no fins and no jaws. Distinct trunk is between head and tail. Head is independent of trunk. Pharynx separates digestion and respiratory pathways.
backbone
Cartilage backbone supports larger size and more speed.
digestion
Jawless fish prey on small organisms by scavenging and parasitism. They have a sucking disc around mouth. Some agnatha are vertebrate parasites. Jawless fish are not filter feeders.
circulation
Heart has one aorta leaving one ventricle and one vena cava entering one auricle.
circulation: blood
Jawless-fish have hemoglobin with one protein sequence.
skin
Outer-skin epidermis layer is protective and smooth. Inner-skin dermis layer contains blood vessels, skin glands, and neurons.
nervous system
Jawless fish have three brain parts: forebrain for smell, midbrain for sight, and hindbrain for hearing. Telencephalon has olfactory bulb. Optic tectum is for sight. Cortex has three cortical layers. Cerebellum associates with hindbrain for sensorimotor coordination. All vertebrates have similar brainstem serotonin-neuron patterns. Spinal cord distributes nerves to body and collects sense signals.
senses
Vestibular system has one or two semicircular canals and helps balance and vision. Frontal eyes, with no eye muscles and no lens, are for pattern detection and make retinoic acid. Jawless fish can detect prey and mates. Parietal eyes can detect sunlight level. Nostrils aided smell.
senses: pain
Jawless fish seem to feel pain.
behavior
Jawless fish can control sucking.
development
Neural crest is at neural-groove edges.
life cycle
Most jawless fish spawn in fresh-water streams, develop into larvae, metamorphose to adults, and swim back to ocean.
Eel-shaped cyclostomes {hagfish} can have round mouth, have eight tentacles, and eat dead fish by boring. Tongue has horny teeth.
Eel-shaped cyclostomes {lamper eel} {lamprey} (Petromyzontidae) has sucking mouths.
Extinct fish {jawed fish}| (Gnasthostomes) lived in ocean and had jaws.
evolution
Gnasthostomes were cartilaginous-fish and bony-fish ancestors.
bone
Tissue calcification makes tissue firmer. Bone allows strong muscle attachments. Bone allows more shapes, because parts can be soft, medium, or hard. Retinoic acid became homeotic-gene regulator, allowing vertebrates to have head bone formation to create cranium to encase and protect brain and allow more muscle-attachment sites for head movement. Neural crest allows new skull bones, jaws, teeth, peripheral nerves, and dentine plates, under homeotic-gene control.
bone: jaw
Head bones evolved to make muscled and bony jaws, which opened larger and allowed grasping, for greater food intake. Bony jaws were possible because vertebrates had evolved heads separate from bodies and had evolved homeotic genes and gene regulators.
blood
By gene duplication, hemoglobin had four protein sequences.
senses
Jawed fish had eye muscles and eye lenses and so better vision. Vestibular system had three semicircular canals.
nervous system
Jawed fish had thalamuses. Cerebellum was larger. Early jawed fish evolved oligodendroglia, which make myelin, which allows faster saltatory conduction and requires less energy to restore ion balance.
Chondrichthyes {cartilaginous fish}| include shark, skate, stingray, and electric ray. Sharks are fast, but others are slow. Cartilaginous fish live in ocean. They have cartilage skeletons. They have paired jaws. They have two fin pairs. They have scaly skin. They have five to seven gill pairs, which send water from mouth out gill slits. They have teeth that are large scales. They have motor maps in optic tecta. They represent sensations in midbrain.
Skates {skate} have wing-like pectoral fins and are flat diamond-shaped bottom feeders.
Rays {ray, fish} have wing-like pectoral fins and are flat and diamond-shaped.
Torpediniformes {electric ray} has electric organs on head sides and stays near bottom.
Tropical rays {manta ray} can be very large, pelagic, and plankton and small-fish eaters.
Rays {sawfish} can have sharp teeth on long flat snouts.
Dasyatidae {stingray} has long tail with one or more spines with poison. Spines are modified dorsal fin rays.
Sharks {shark} are carnivorous and have heterocercal caudal fins, tough skin, and small scales.
Large northern sharks {basking shark} can be plankton eaters and swim slowly at sea surface.
Tropical sharks {hammerhead shark} can be medium-size, be live bearing, and have flat bar-shaped heads with eyes at ends.
Jawed bony fish {teleost}| {bony fish} evolved.
bone
Fins have bony rays with muscles, allowing better control. Later, rays became fingers and toes.
skin
Bony fish have skin scales.
mouth
Bony fish have mouth at front end, allowing larger opening, more shape and size variation, more growth while maintaining streamlined shape, and larger brain, because fish can maintain streamlined shape even if brain grows.
lung
Some bony fish have lungs surrounded by blood vessels, allowing gas exchange from blood to air, to control buoyancy and extract more oxygen.
nervous system
Fish can detect features, intensities, textures, flows, and surfaces.
types
Fish include sea horse, lungfish, bass, trout, perch, flounder, swordfish, angelfish, tropical fish, goldfish, cod, barracuda, smelt, sardine, and anchovy.
dark gray, medium size, southern, long side fins, flat {angelfish} {angel fish}.
large mouth, filament for luring prey {angler fish} {goosefish}.
Toxotidae {archer fish} {archerfish} shoot water from mouth at insects and live in warm water.
Sphyraena {barracuda} have long cylindrical bodies and projecting lower jaws with long strong teeth.
Fish {crucian carp} can use lactic acid to make ethanol and so does not need oxygen.
Tropical fish with large fins {flying fish} (Exocoetidae) can glide after jumping from water.
large, sea-bass shape {grouper} (Epinephelus) (Mycteroperca).
Fish {grunion} can spawn on beaches at full moon in spring, at highest tide.
tropical, medium size {grunt}.
small fish {minnow}.
long, tubular, tropical {pipe fish}. family Syngnathidae.
Fish {porcupinefish} inflates by swallowing water or air when threatened, relates to puffer fish, and has spines.
East Coast, tropical {porgy} {sea bream} {scup} (Pagrus) (Sparidae).
Fish {blowfish} {swellfish} {globefish} {balloonfish} {puffer fish} (Tetraodontidae) (Tetraodontiformes) inflates by swallowing water or air when threatened and has no spines.
Fish {remora} (Echeneidae) sucking disk can attach to sharks.
Fish {seahorse} can be small, swim vertically, have bony plates, and have horse-head shaped heads.
large, broad shovel-shaped snout, freshwater, ancient {sturgeon}.
bottom feeding, no scales, broad head, wide mouth {toadfish}.
Deep ocean fish {viperfish} (Chauliodus macouni) eats crustaceans and small fish. First dorsal fin has photophores to attract prey.
North Atlantic, soft {weakfish} (Cynoscion regalis).
saltwater white fish {whitefish, fish}, except herring.
long thin upper jaw, related to sailfish and spearfish {marlin} (Makaira) (Tetrapturus).
large flat dorsal fin {sailfish}.
large, long bill at snout tip {swordfish, fish}.
Gulf of Mexico, long body, large silver scales, up to 2 meters and 100 kilograms {tarpon}.
Eels {eel, fish} live in fresh water and spawn in Sargasso Sea in North Atlantic Ocean.
large, colored, tropical reef {moray eel}.
long body, pointed tail {wolffish} {wolf eel}.
flatfish {flounder, fish}.
flatfish {halibut, fish}.
flatfish {plaice, fish}.
flatfish {pompano, fish}.
small flatfish, Pacific coast {sand dab}.
flatfish {sole, fish}.
large European flatfish {turbot}.
small, silver {anchovy, fish} (Engraulidae).
sprat {brisling}.
northern {herring, fish} (Clupeidae).
Small fish {pilchard, fish} can include sardines.
small, northern, silver, ocean and fresh water {smelt, fish}.
small European herring {sprat} (Clupea sprattus).
young or small pike {pickerel, fish}.
long, slender, duckbill {pike, fish}.
Teleosts {salmon, fish} (Salmonidae) can spawn in fresh water and live in sea, returning to home stream by smell.
northern coastal Atlantic, pink inside {Atlantic salmon}.
salmon {sockeye salmon}.
medium to large size, silver {trout, fish}.
very large {piracucu} {paiche} {arapaima} (Arapaima gigas).
North America, lake {bass, fish}.
east and central United States sunfish {bluegill}.
smooth skin, large flat head, long hairs {barbel} near mouth, ocean and freshwater {catfish}.
Europe, thick, spindle shape {chub}.
east Asia, red-orange color {goldfish} (Carassius auratus).
fresh water or ocean {mullet} (Mugilidae).
South America, tropical {piranha} (Serrasalmus).
Male fish {stickleback} can fight fish with red underbellies and court fish without red underbellies {key stimulus}. Stickleback fish build nests, using innate behavior.
small, South America and West Indies {guppy}.
live young, North and Central America {swordtail} (Poecilidae) (Cyprinodontiformes), related to southern platyfish {platy}.
small, striped, tropical, India {zebra fish} (Brachydanio rerio).
Fish {electric fish} (Gymnarchus) tail can generate weak electric voltages that cause discharges at 300/second. Electric organs along body detect electric field. Dorsal fin undulates to move fish forward without using tail. Objects in water alter electric field.
eel-like, South America {electric eel}.
Perciformes, Percomorphi, or Acanthopteri {perciform fish} {percoid} are largest vertebrate order, are 40% of all fish, look like perch, have ray fin, and began in late Cretaceous.
northern {cod} (Gadus morhua) (Gadidae).
Antarctica and south South America {white-blooded fish} {ice fish} (Channichthyidae).
Zanclus cornutus {moorish idol} (Zanclidae) is small tropical marine fish. Genus Heniochus butterfly fishes resemble Moorish Idols.
fresh water or ocean {perch, fish}.
small, America {sunfish} (Centrarchidae).
amber color, fork tail, warm water {amberjack} (Carangidae) {carangid} {hamachi}.
percoid {jack fish}.
carnivore, bluefin/horse mackerel, tropical {pilot fish} (Naucrates duclor).
tuna-like {skipjack} (Euthynnus).
tuna {albacore, fish}.
tuna {bigeye}.
large tuna {bluefin} {horse mackerel}.
streamlined {bonito, fish} (Sarda).
tuna {yellowfin}.
tropical {tunny} (Thunnus).
northern {mackerel, fish}.
Some jawed bony fish {salt-water lobe-finned fish} {lobefin fish} had lobefins, allowing crawling onto shore. Later, stumps became appendages.
lung
Nasal passages had internal nares openings into windpipe inside body, allowing more efficient breathing, moist and filtered air, and alternative air paths.
types
Rhipidistians are extinct. Later, Rhipidistians evolved to amphibians. Coelacanth fish (Crossopterygii) still survive today and are like Rhipidistians.
Paleozoic fish {coelacanth} are large, are bright blue to brown, have lobefins, and live in deep ocean.
Some lobefin fish {fresh-water lobefin fish} {fresh-water lobe-finned fish} had adults that lived in fresh water and on land.
fresh water
Because fresh water has no salt, they had to maintain hydrogen and salt ion balance in blood and tissues and had to control water drinking. Seawater ion balance is similar to that in cells. To live in fresh water, organisms need to pump out cell water to maintain salt and protein concentrations and to prevent bursting.
hind limb
Rear lobefins became specialized for pushing. Later, they became legs.
teeth
Teeth were for grasping but not cutting or grinding. Teeth grew, fell out, and grew back, repeating as animals grew.
hearing
Eardrum amplified sound for better hearing.
lung
They breathed using lungs. They had no gill bones and began gill loss. Later, gills closed.
evolution
Land vertebrates evolved from lobe-finned bony fish.
lobe-finned fish and tetrapods {sarcopterygian}.
Lobe-finned fish one meter long developed into four-legged fish {tetrapod}| (Tetrapoda) in shallow, plant-filled, fresh or brackish water, in tropics and subtropics. Perhaps, front limbs helped lift head above water to get more oxygen.
fins
Pectoral and pelvic fins gained feet and toes. Tetrapods have no tail fins.
bone
Vertebrae became interlocking. Neck became flexible after losing bones that joined head and shoulders. Snout became longer and head flatter. Gill and neck bones {opercular bone, tetrapod} disappeared. Longer ribs appeared. Pelvis became larger.
evolution
Most early lobefin fish were not tetrapod ancestors: Kenichthys [-400000000], Osteolepidids [-394000000], Eusthenopteron [-388000000], Panderichthys [-385000000], Elpistostege [-384000000], and Livoniana [-384000000]. Most early tetrapods are extinct and were not living-tetrapod ancestors: Elginerpeton [-378000000], Ventastega [-370000000], Acanthostega [-368000000], Ichthyostega [-366000000], and Tulerpeton [-364000000].
Sarcopterygians {lung fish} {lungfish} can have one or two lungs, live in freshwater, and have lobefins.
Frogs, toads, basilisk lizards, and salamanders {amphibian} are cold-blooded.
skeleton: palate
Cartilage secondary palate allows breathing and eating at same time, by closing either nose or mouth.
skeleton: neck
Joint between head and trunk {neck, amphibian} allows head scanning and turning.
skeleton: pelvis
Amphibians have a pelvis, allowing hind limbs more mobility on land.
skin
Amphibians have vascularized smooth and moist skin, which can change color using pituitary intermedin hormone. Some amphibians secrete poison.
skin: claws
Claws allow better grasping by hands and feet, for better traction on land.
circulation
Four-chambered heart, divided into auricle and ventricle for pumping blood to lungs and auricle and ventricle for pumping blood to body, allows blood circulation through lungs and improved respiration.
lung
Amphibians have primitive lungs.
excretion
Amphibians have kidneys to regulate hydrogen and salt ion balance.
reproduction
Amphibians reproduce like fish.
senses: smell
Pharynx-top vomeronasal system is for olfaction, mainly for pheromones, and depends on different genes than olfactory bulb.
senses: vision
Thalamus and optic tectum evolved for vision, possibly localizing objects and detecting size.
nervous system
Amphibians can detect motion and location and use behaviors that require knowing trajectories and depth. They represent sensations in midbrain.
evolution
Amphibians evolved from Rhipidistian lobefin fish.
development
Like chordates, life stages are egg, larva, and adult. Egg and larval stages live in water. Adults stay on land. Eggs become tadpoles, which have gills, eat plants, and metamorphose to adults. Metamorphosis is under thyroid-gland control, releasing hormone after pituitary-gland signal.
regeneration
Salamanders can regenerate legs and tails.
Amphibians have soft palates {secondary palate}, allowing breathing and eating at same time by closing either nose or mouth.
Amphibians reproduce as fish do. Eggs become larvae {tadpole}|, which have gills, eat plants, and metamorphose to adults.
Toad or frog larvae {polliwog} initially have no legs, have gills, and live in water.
Mexican Ambystoma salamanders {axolotl} can retain gills and mature without metamorphosis.
Frogs {bull frog} can be large, with low croaks.
Amphibians {frog} can identify flies as small-size dark spots moving at rates. Frogs do not perform complex shape analysis [Lettvin et al., 1959]. Some tropical frogs have skin alkaloid poisons {pumiliotoxin}, such as PTX 251D.
small salamander {newt}.
small, lizard shape {salamander, amphibian}.
land, rough skin {toad}.
First reptiles {stem reptile} were anapsids. Cut-lizard cotylosaur was low, stocky, and 20 centimeters to two meters long. Reptilia {reptile} include gecko, snake, iguana, turtle, crocodile, alligator, and lizard.
classes
The six reptile subclasses have different skulls: anapsid, diapsid, euryapsid, parapsid, synapsid, and therapsid.
evolution
Evolution was anapsid to diapsid to synapsid to therapsid. Euryapsids and parapsids evolved from diapsids.
land
Reptiles can live whole life cycle on land.
development
Reptiles have no larval stage in water. They develop continuously from egg to adult, requiring mechanisms for replacement and renewal.
skin
Thick dry leathery skin, with horny scales, allows continuous dry land existence, because it conserves water.
respiration
Reptiles have lungs.
skeleton: bone
Bones have growth rings in seasonal climates, with few blood vessels and haversian canals.
skeleton: pelvis
Reptiles have a strong pelvis, allowing running and/or standing on hind legs.
skeleton: jaw
Reptiles have muscles and jaws for chewing, not just grasping and tearing.
reproduction
Reptiles reproduce by intercourse and have internal fertilization. They lay eggs with leathery shells on land. An egg sac {amnion} holds water, so egg does not need to get water from sea, lake, or stream. Reptiles have egg-laying rituals, courtship rituals, territoriality, and sexual intercourse behaviors.
cloaca
The same body opening is for anus and reproductive tract.
muscle
Reptiles have only involuntary muscles controlled by automatic neuron circuits in ganglia and paleocortex.
nervous system
Cerebellum outer-layer basket cells process sensorimotor information and allow walking, running, and chewing. Brains have two-layered cortex and several ganglia. Paleocortex controls involuntary muscles and glands. Cortical neurons send axons to other cell layers and regions and receive signals from other paleocortex layers and regions. Paleocortex areas analyze information.
senses
Sense organs with more than one cell layer preprocess signals before sending them to brain. Median eye detects infrared light and later became pineal gland.
Early reptiles were, and most reptiles are, cold-blooded animals {poikilotherm}|.
Therapsid warm-blooded animals {endotherm}| had basal metabolism four times higher than poikilotherms and needed 10 to 30 times more food than poikilotherms.
The same body opening {cloaca}| can be for anus and reproductive tract.
Reptiles have two-layered nerve sheets {paleocortex}| connected to several ganglia, allowing more complex information processing and distribution. Paleocortex cerebrum covers forebrain and has distinct input layer and output layer.
Geckoes tilt toe hairs 30 degrees to let go while walking {toe peeling, hair}|.
Reptiles have one eye {median eye}| to detect infrared light. Later, median eye evolved to become pineal gland.
In reptiles, skull front-middle eye {parietal eye}| {third eye} detects sunlight level, regulates daily activities, and regulates seasonal responses to light and temperature. Parietal-eye light level affects puberty, sexual activity, hibernation, and aestivation.
Reptiles {reptile types} are anapsids, diapsids, synapsids, and therapsids.
Anapsids {anapsid} (Anapsida) were the first reptiles and are mostly extinct, except for turtles and tortoises (Chelonia), which have hard shells. Cut-lizards {cotylosaur} {cut-lizard} were low, stocky, two meters long, and the most-primitive reptiles. Other reptiles evolved from cut-lizard anapsids.
Chelonia {chelonian} are turtles and tortoises.
Sea turtles {sea turtle} have flipper legs and bony shells and lay eggs on shore.
Freshwater turtles {snapping turtle} (Chelydridae) can have rough shells and hooked beaks.
Aquatic turtles {soft-shelled turtle} can have flat flexible shells with leathery skin.
fresh water, North American, web-footed, tortoise {terrapin}.
plant eater, land, claws {tortoise, reptile} (Testudinidae).
beak, bony or leathery shell {turtle}.
Extinct aquatic reptiles {euryapsid} (Euryapsida) had long necks, small heads, long tails, and bloated bodies. They paddled, swam, and were up to 17 meters long, such as elasmosaurus. Euryapsids evolved from anapsids.
Diapsids {diapsid} (Diapsida) include tuatara, rhynchocephalia, extinct sphenodon, extinct ichthyosaur, and lepidosaurs. Lepidosaurs became squamata snakes and lizards.
evolution
Diapsids came from anapsids. Diapsids evolved to parasids and synapsids.
parietal eye
Parietal eye detected sunlight level and helped regulate daily activities and responses to light and temperature.
neck joint
New neck joint type, between head and trunk, put head at angle to vertebrae. Head turns around different axis than trunk, allowing freer head movement and improved ability to catch and eat prey. The new turning axis required triangulation to locate objects in space.
teeth
New teeth types were for cutting and chewing, to match new jaw types.
Diapsids include scaled lizards {lepidosaur} {scaled lizard}. Lepidosaurs became squamata, which became snakes and lizards.
snakes and lizards {squamata}.
Squamata {lizard} can have four legs, scales, and tails.
American Basiliscus lizards {basilisk} have crests and can run on hind legs.
Lizards {chameleon} can change color.
Lizards {gecko} can have 500,000 hairs {setae} on each foot. Hairs split into hundreds of ends. If ends are perpendicular to surface, they stick by van der Waals forces. Geckos tilt toe hairs 30 degrees to let go while walking {toe peeling, gecko}.
large {Gila monster}.
Lizards {horned toad} can have head horns and body spines.
horned {iguana}.
large {monitor lizard}.
Squamata {snake, animal} can have scales and no legs.
long thin ocean snake {sea snake}.
swimming snake {water snake}.
constrictor {anaconda}.
constrictor {boa constrictor}.
constrictor, jungle {python}.
poison {adder}.
poison {asp}.
poison {black adder}.
poison, forest {bushmaster}.
poison {cobra}.
poison {copperhead}.
poison {coral snake}.
poison, woods {cottonmouth}.
poison {pit viper}.
poison, desert {rattlesnake}.
poison, desert {sidewinder}.
poison {viper}.
poison, swimming {water mocassin}.
Diapsids {sphenodon} were one meter long, had large beak-like snouts, and had spines down back. They are extinct. Sphenodons had third eyes. They had nictating membranes. Sphenodons were archosaur ancestors.
Diapsids {rhynchocephalia} {rhynchosaur} were small, had beaks, and included sphenodon.
Diapsids {archosaur} had two large back limbs, two small front limbs, long tails, and teeth in sockets. They are extinct. Archosaurs evolved from sphenodons. Archosaurs include thecodonts.
Diapsids {thecodont} had insulation, had reptilian teeth, and included Troödon, Pterodactyl, and Pteranodon [-220000000]. They are extinct. Thecodonts came from archosaurs. They are bird, crocodile, sauropod, thecopod, pterosaur, Ornithischia, and Saurischia ancestors.
Thecodonts {pterosaur} (Pterosaura) had webbed wings on little fingers. Perhaps, pterosaurs had hair. They had light and long heads. Early pterosaurs had teeth and long tails, but later ones had neither. They are extinct. Pteranodon had seven-meter wingspan. Pterodactyl flew. Birds evolved from pterosaurs.
extinct flying reptile {pterodactyl}.
Thecodonts (Ornithischia) {bird hip} were herbivores. Ornithischia evolved from thecodonts. Anatosaurus had duckbill with flat wide jaw. Ankylosaurus had large bony plates on back, spikes on sides, and bony ball at tail tip. Triceratops had three horns on head and broad bone on neck.
Ornithischians {stegosaur} can eat plants, have back bony plates, and have spiked tails.
Crocodiles and alligators (Crocodilia) {crocodile, animal} evolved from thecodonts.
broad short snout {alligator}.
American, related to alligators {caiman}.
Extinct thecodonts {crurotarsan}| were like large crocodiles. Crurotarsans included phytosaurs, rauisuchians, and aetosaurs. Phytosaurs lived in water and were up to 13 meters long. Rauisuchians lived on land and were up to 10 meters long. Aetosaurs had armor. They flourished from 230 million years ago to 201 million years ago, until Late Triassic catastrophe, which dinosaurs survived. Crurotarsans are crocodile and alligator ancestors.
Thecodonts (Saurischia) {lizard hip} were bipeds with feet like thecopods or quadrupeds with feet like sauropods. They are extinct.
Saurischia quadrupeds {sauropod} had feet like lizards. Sauropods were large plant eaters. They had long necks and tails. They included Brontosaurus, Brachiosaurus, Diplodocus, and Apatosaurus. They are extinct. Prosauropods hatched with no teeth, four legs, and short tail. Perhaps, parents fed them. After they hatched, neck grew, tail lengthened, and forelimbs did not grow. Later sauropods had four legs and derived from juvenile stage.
vegetarian {brontosaur}.
Extinct Saurischia bipeds {thecopod} had feet like mammals.
Extinct Saurischia {theropod} had feet like mammals, were coelurosaurs or carnosaurs, were cold-blooded, had large range, and had few competitors.
Extinct theropods {carnosaur} were large meat eaters, such as Tyrannosaurus, Carcharodontosaurus, and Spinosaurus.
Extinct theropods {tyrannosaurus} were carnivores, had two legs, and had short arms.
Extinct theropods {coelurosaur} were fast meat eaters with tails and long necks.
Extinct theropods {gigantosaur} (Mapusaurus roseae) were carnivores.
Parasids {parasid} (Parasida) include extinct fish-lizard ichthyosaurs. Parasids lived in ocean, were one to twenty meters long, and had long noses. Parasids evolved from diapsids.
Extinct parasids {ichthyosaur} lived in ocean 245 million to 90 million years ago. At first, they were lizard-like and undulated like eels and then were fish-like and flipped tails like fish. They were one to twenty meters long, had long noses, were carnivores, and ate mostly animals like squid. Like all non-mammals, they had very large eyes with sclerotic rings.
Synapsids {synapsid} (Synapsida) had new joint type between head and trunk, so head was at angle to vertebrae and turned around different axis than trunk, which later led to free head movement. They had new teeth types for cutting and chewing. They are extinct. Synapsids came from diapsids. They are therapsid and mammal ancestors.
Extinct finback mammal-like synapsids {pelycosaur} were 60 centimeters long, had canine teeth, and chewed using jaw and jaw muscles different than anapsids and diapsids. Two-meter-long Dimetrodon had dorsal fin for warming and cooling blood [-260000000]. Pelycosaur species became Pristerognathids.
Extinct synapsids {pristerognathid} weighed 50 kilograms, were fast trotters, were endotherms, and included antesaurus, gorgon, and moschorhinids. They evolved from pelycosaurs. They gave rise to therapsids.
Extinct synapsids {therapsid} lived in south Gondwana.
endotherm
As endotherm warm-blooded animals, with basal metabolism four times higher than poikilotherm cold-blooded animals, they needed 10 to 30 times more food. Optimum temperature for metabolism uses heating and cooling mechanisms {thermoregulation, endotherm}, resulting in much higher available energy all day and allowing more activity throughout day, rather than just at midday.
hair
Hair or feathers helps temperature regulation.
hearing
Warm-bloodedness requires better hearing, because daily activity requires more warning signals and other communications. Therapsids had ear pinnae to gather sound better.
larynx
Therapsids had larynx, allowing sound production, accompanied by ability to hear and find meaning in sounds.
evolution
Therapsids evolved from Pristerognathids. Therapsids are mammal ancestors.
Therapsids had outer ear structures {ear pinna}, to gather sound better.
Therapsids had optimum temperature for metabolism, maintained by heating and cooling mechanisms {thermoregulation, therapsid}|.
Extinct therapsids {cynodontia} {cynodont} were dog-sized, were nocturnal, and slept curled up.
rib
They do not have lumbar-vertebrae ribs.
jaw
Lower jaw had dentary bone and had big canine teeth, incisors, and molars with multiple cusps. Snout and lips had muscles, possibly to suckle, and possibly whiskers.
palate
Hard palate enabled simultaneous breathing and chewing.
smell
Turbinals held olfactory receptors and warmed and humidified air. Number of olfactory genes became thousand, by gene duplication.
eye
Being nocturnal, they had large eyes and post-orbital bar.
They also had parietal eye.
evolution
They evolved from therapsids. They were mammal ancestors.
types
Cynodonts included Thrinaxadons and Procynosuchus.
Cynodont lower jaw had one main bone {dentary} and had big canine teeth, incisors, and molars with multiple cusps.
Extinct separate therapsids {dicynodont} were herbivores and included Lystrosaurus.
Cynodonts {Chiniquodontid} had teeth for meat eating.
Leopard-sized cynodont plant-eaters {traversodontid} had incisors and cheek teeth.
Birds {bird} have wings and feathers.
feathers
Feathers are modified reptile scales, decrease water and heat loss, and aid flying. Light scattering causes blue jays to have blue feathers. Transparency causes white feathers [Matthews, 1973]. Females typically are drab, and males have color.
flying
Bigger birds fly faster. Penguins cannot fly but use wings for swimming by flying under water.
bone
Birds have hollow bones.
metabolism
Birds live several years. They have fast heartbeat, high blood sugar, and high blood pressure. They have fast transit time for digestion. Birds are warm-blooded.
respiration
Birds have lungs that exhale actively and inhale passively, by continuous airflow, because lung air sacs fill spaces between organs and in wings.
reproduction
Birds have fertilization inside female. Birds have eggs with hard shells.
signals
Birds have 10 to 40 different signals [Matthews, 1973]. Bird songs {birdsong} can be instinctual, learned, or irregular and are for warning, mating, or territory.
nervous system
Birds have optic tectum.
development
Both parents care for eggs and chicks.
evolution
Birds evolved from thecodont pterosaurs.
types
Protoavis [-220000000] had good eyes and bad olfaction and hunted by day. Special shoulder joints allowed later flying, as in Archaeopteryx [-150000000] and Confuciusornis sanctus [-120000000].
high nest {aerie}|.
Birds have lungs that exhale actively and inhale passively, by continuous airflow, because lung extensions {air sac, bird} fill spaces between organs and in wings.
Birds are warm-blooded {homoiothermic, bird} {homoiotherm}|, with high body temperature, 107 F to 113 F.
Some birds winter in one location and summer in another location {migration, bird}, up to 12,000 miles apart. Daylight change affects hypothalamus and pituitary, which affect gonads, which start migration. Increased sex hormones start migration. Migratory birds and homing pigeons use Sun, Moon, Earth magnetic field, air pressure, polarized-light plane, and star-field rotation to establish north-south axis and general directions. They use wind direction, other-bird call notes, and landmarks when close to home.
In extremities, water birds have blood vessels {rete mirabile}| that conserve heat and oxygen pressure by countercurrent exchange.
Ostrich has rudimentary {vestigial}| wings.
Anterior-forebrain region {wulst}| has a visual map.
young swan {cygnet}.
Young birds {fledgling bird}| have feathers but cannot fly.
baby goose {gosling}.
baby bird {hatchling}|.
small rooster {bantam rooster}.
rooster {cock}.
male duck {drake}.
male goose {gander}.
female bird {hen}|.
first-year hen {pullet}|.
male chicken {rooster}.
shot or captured bird set {brace, bird}|.
Baby-bird set {brood}| can be from one mating season.
small quail or partridge family or flock {covey}|.
geese group {gaggle}|.
bird nesting place {rookery}|.
small, hovers, long bill, drinks nectar {hummingbird}.
Large tail can expand upward {peacock, bird}.
running, crested, southwest North America, brown {roadrunner}. Geococcyx californianus.
feathers, neck and feet scales, teeth, claws {archaeopteryx}.
extinct large bird {dodo}.
large, black {blackbird} {red-winged blackbird} {yellow-headed blackbird}.
North-American blackbird {cowbird}.
large, black, American blackbird {grackle}.
tropical Asian starlings {mynah bird}.
medium size {redwing blackbird}.
medium-size {starling}.
In Australia, male birds {bower bird} build bowers to attract females.
bower bird {catbird}.
Corvids {corvid} include ravens, crows, jays, magpies, and nutcrackers.
large, black {crow}. New Caledonian crow can put things together to make tool to get food from inside hole.
long tail, black-and-white, harsh call {magpie}.
Large, black crow-like birds {raven} (Corvus corax) eat mostly carrion and hide pieces over kilometer radius. They make pretend hiding places. They cut and arrange food pieces so they can carry them.
size
They weigh more than kilogram and have wingspan more than meter.
skills
They operate in environment with many other ravens competing for food. They observe situation then choose action. They can distinguish species individuals and large predators. They like to play, roll on back, throw small pebbles at predators using beaks, and lead predators to prey. They play with large predators when young and eat near them when old. They can make and manipulate tools.
European crow-like bird {rook}.
medium size, black, loud call {jay}. Scrub jay can put different food in different places and different times, and remember food type, place, and time together. Perhaps, they have episodic memory, which requires what, when, and where.
medium size, blue, loud call {blue jay}.
Ducks {duck} have Herbst corpuscle vibration detectors, like Pacinian corpuscles, around bill.
medium size {mallard duck}.
medium size, diving {merganser} {sheldrake}.
medium size {teal}.
medium size {wood duck}.
medium size, plump body, feathered legs and feet {grouse, bird} {ruffed grouse} {arctic grouse} {ptarmigan}.
small {quail, bird}.
large {turkey, bird}.
medium size {goose, bird}.
large {Canada goose}.
large {loon}.
large {parrot, bird}.
small, blue {cockatoo}.
large, big beak {macaw}.
small, blue {parakeet}.
large, big beak {toucan}.
medium or large {penguin}.
large {Adelie penguin}.
medium size {petrel}.
medium size {stormy petrel, bird}.
medium size, white, short legs {pigeon}.
medium size, white, short legs {dove, bird}.
medium size, white, short legs {homing pigeon}.
medium size, gray, whimpering call, short legs {mourning dove}.
medium size, short legs {rock pigeon} {stock dove} {ringdove} {wood pigeon} {turtledove}.
medium size {plover}.
American plover {killdeer} lives in inland waters and fields and has unique call.
Large African birds {secretary bird} can eat reptiles and have long legs.
Old World, strong hooked bill {shrike} {loggerhead}.
large, scavenger {buzzard}.
large, scavenger {condor}.
large, scavenger {turkey buzzard}.
large, scavenger {vulture}.
large {eagle, bird}.
large {American eagle}.
large, white head {bald eagle}.
medium size {falcon}.
small {peregrine falcon}.
medium to small {hawk, bird}.
small {nighthawk} {bullbat} {mosquito hawk}.
small {sparrowhawk}.
Owls {owl, bird} have no independent eye movement but have head-movement map in optic tectum.
medium size {barn owl}.
medium size {great horned owl}.
medium size {screech owl}.
ostrich, emu, rhea, kiwi {ratite}.
large, flightless, Australia, related to ostrich and cassowary {emu} (Dromiceius novaehollandiae).
small, flightless, New Zealand {kiwi, bird} (Apteryx) (Apterygidae).
large, white, very large egg {ostrich}.
Birds {wading bird} can walk in shallow water to find small grubs and fish.
large {crane, bird}.
large, brownish, wading {curlew}.
heron, long white feathers {egret}.
large, pink {flamingo}.
medium size {heron}.
wading, temperate and tropical climates {ibis} (family Threskiornithidae).
medium size, marsh {rail, bird}.
medium size {sandpiper}.
medium size, shore {snipe}.
medium size {spoonbill}.
medium size, wading {stilt}.
large {stork}.
medium size migratory, related to snipe and sandpiper {woodcock, bird}.
Cardinals, sparrows, bluebirds, and other birds {songbird} make melody, perch (Passeriformes) {perching bird}, and build nests.
small {bluebird}.
medium size {bobolink}.
medium size {bob-white}.
North America, bill curves down {brown creeper}.
small {bunting, bird}.
small {canary}.
medium size {cardinal, bird}.
small {chickadee}.
Other birds hatch its eggs {cuckoo}.
small {goldfinch}.
small {indigo bunting}.
medium size {nightingale}.
small {nuthatch}.
North American medium-size bird {phoebe} flicks tail.
large, North American, {purple martin}.
medium size {redbird}.
medium size {robin}.
small {sparrow} {English sparrow} {chipping sparrow} {song sparrow} {white crowned sparrow} {white throated sparrow}.
small {titmouse} {tit}.
medium size, eats insects {vireo}.
medium size {waxwing} {cedar waxwing}.
medium size {whippoorwill}.
small {wren} {house wren} {cactus wren}.
small {finch}.
long-tailed, American {towhee}.
medium size {lark}.
medium size {meadowlark}.
medium size {skylark}.
medium size {oriole}.
medium size {Baltimore oriole}.
medium size {tanager}.
medium size {scarlet tanager}.
medium size {thrasher}.
small {brown thrasher}.
Medium-size thrashers {mockingbird} can imitate bird calls.
medium size {thrush} {wood thrush} {hermit thrush}.
medium size {chat, bird}.
medium size {warbler}.
American warblers {ovenbird} can make dome-shaped nests on dirt.
medium size {yellowthroat}.
medium size {swallow}.
medium size {barn swallow}.
medium size {flycatcher}.
large, American, flycatcher {kingbird}.
medium size {swift} {chimney swift}.
large {swan}.
large {trumpeter swan}.
wading or swimming birds {waterfowl}.
large {albatross}.
large, extinct {auk}.
medium size {bittern}.
medium size {coot}.
large {cormorant}.
swimming, diving {grebe}.
medium size {gull}.
large {kingfisher}.
large {osprey}.
large {pelican}.
medium size {sea gull}.
medium size {tern}.
Herbst corpuscle vibration detectors, like Pacinian corpuscles, are in tongue {woodpecker} {downy woodpecker} {pileated woodpecker} {redheaded woodpecker}.
medium size, North American {flicker}.
Small American woodpecker {sapsucker} eats sap from apple and maple trees.
Mammals {mammal} evolved from therapsids.
types
Mammals (Eutheria) are extinct multituberculates, monotremes like platypus, marsupials like kangaroo, and placental mammals (Placentalia).
evolution
Eutheria evolved from Theria. Early mammals included 30-gram Megazostrodon [-220000000] and Triconodon.
behavior
Early mammals hunted alone, signaled, and had territoriality. Voluntary muscles allowed rapid locomotion and good control.
body temperature
More food and oxygen allowed higher metabolic rate, more muscle action, and warm-bloodedness {homoiothermic, mammal}. Body temperature was higher than surroundings but lower than humans have now. Homeostasis allowed wider territory ranges and longer maturation times. Because early mammals were nocturnal, they only needed heating. Panting and sweating to cool body came later.
body temperature: hair
Mammals have hair, rather than scales, plates, or feathers, covering skin, to aid thermoregulation and insulation. They have sweat glands.
respiration
Diaphragm, bony palate, and turbinals allowed more oxygen and better respiration. Specialized red-blood-cell erythrocytes carry heme to provided better energy and oxygen management. Only warm-blooded animals can have erythrocytes.
reproduction
Reproductive-tract and digestive-tract openings became separate, allowing better and more reproduction and childcare varieties. Early mammals had birth rituals, courtship rituals, and sexual intercourse.
reproduction: mammaries
Sweat glands evolved into mammary glands, which provided balanced nutrition to young. Only warm-blooded animals can make milk. Milk redefined mother and father roles relative to children and allowed longer maturation and more brain growth. Mothers cared for babies until weaning.
teeth
Mammals have three teeth types: incisor, canine, and molar. They have two teeth sets, baby and adult, instead of continuous replacement, allowing head to be greater size in early life. Deciduous baby teeth and permanent adult teeth, rather than having continual replacement, allowed more teeth variety and more chewing. Head can be greater size in early life.
nervous system
Hippocampus and archicortex replaced some thalamus functions. Larger cerebellum allowed more sensorimotor coordination.
nervous system: involuntary muscle
Automatic circuits in ganglia and paleocortex control involuntary muscles, as in reptiles and birds. In lower mammals, archicortex and mesocortex or paleocortex add a supragranular layer to lower-animal granular and subgranular layers. In middle mammals, both supragranular and granular layers thicken, but subgranular layer stays the same.
nervous system: neocortex
In higher mammals, neocortex thickens, cellular complexity increases, newborn unmyelinated areas increase, and brain has more fissures. Paleocortex extension above ganglia forms neocortex to control voluntary muscles. All mammals have four lobes and three fissures in neocortex. Neocortex had four layers with minicolumns and interconnected specialized modules, to make maps for more complex local processing and more integration. Larger cerebrum allowed more spatial and temporal integration.
Higher mammals try alternate strategies to reach goals and identify object and event categories, such as individuals, selves, space, and time. Some mammals learn abstract symbols and categories. Some mammals generalize from specifics and specify objects from general categories. Some mammals learn relationships but cannot use analogies, metaphors, similes, parables, and mental models. Mammals have pleasant and unpleasant dreams. Mammals are curious, sentient, and know object categories, not just specific objects.
senses
Animals evolved new sensation abilities [Dawkins, 1987] [Griffin, 1974] [Griffin, 2001] [Griffin and Speck, 2004] [Haugeland, 1997].
senses: smell
Smell sense developed first, in amygdala and forebrain paleocortex.
senses: vision
At first, small eyes bulged out, as in tree shrews. Optic tectum allowed better object localization and size detection. Mammals typically have no or limited color vision, except for primates.
senses: hearing
Maleus evolved from cynodont articular jawbone, and incus evolved from cynodont quadrate jawbone, to work with stapes. Stapedius muscle controlled stiffness. Outer hair cells paralleled inner hair cells. These allowed hearing frequencies above 10000 Hertz and so high-frequency insect noises and baby cries. Outer hair cells can also change shape quickly, changing frequencies to which inner hair cells respond best. Early mammals had ear pinnae.
Mammals developed from juvenile therapsid cynodonts that matured quickly {pedomorphism}|.
People modified animals {domesticated animal}.
In Eurasia and north Africa, cow and ox came from auroch.
In west and central Asia, sheep came from Asiatic mouflon sheep.
In west Asia highlands, goat came from bezoar goat.
In Eurasia and north Africa, pig came from wild boar.
In south Russia, horse came from wild horses.
In Andes mountains, llama and alpaca came from guanaco.
In north Africa, donkey came from African wild ass.
In southeast Asia, bali cattle came from banteng, which relates to auroch.
In India and Burma, mithan came from gaur, which relates to auroch.
Arabian camel was in Arabia. Bactrian camel was in central Asia.
Reindeer were in north Eurasia. Water buffalo was in southeast Asia. Yak was in Himalayas and Tibet.
Primates live on ground or in small tree branches {fine-branch niche}|, like Australia and South America small nocturnal prosimians and arboreal marsupials.
Early placental mammals had long, sensitive snouts with large hairs {vibrissae} and good smell sense.
female quadruped {dam}.
flock or herd {drove}|.
Animals can have babies {pup, litter} each mating season {litter, pup}|.
Lions live in groups {pride}| with two or three males and five to ten females and cubs.
Mammals besides humans show paw preferences {handedness, mammal} but equally to left or right.
Mammal superior colliculus can integrate multiple senses {multisensory} at same spatial location, while other structures maintain distinct sensations for each sense [O'Regan and Noë, 2001].
Arginine vasopressin aids pair bonding {pair bonding, arginine vasopressin}.
Vocalization echoes give information. Dolphins and bats expanded this ability. Dolphins and bats use sonar {sonar, animal} to locate and categorize objects. They can project known signals into environment, receive reflected signals, and interpret altered signals. Signaling evolved from vocalization. Receiving evolved from auditory-brain sound processing, which locates and categorizes sounds.
Animals that are smart enough to suffer include horse, dog, apes, elephants, and dolphins, because they can do something about conditions that make them suffer {suffering, animal}.
Animal rhythms {biological rhythm}| depend on year, lunar month, tides, and day.
brain clock
Brain can time intervals {brain clock} using striato-cortical loops and frontal-cortex, caudate-putamen, and thalamus dopamine neurons. Clocks can be neuron circuits for each time interval, or neuron populations can code all intervals. Somatosensory lemniscal system can backdate events.
millisecond rhythm
Biochemical reactions have millisecond intervals. Coupled reaction systems can have cycles up to 100 seconds.
second rhythm
Heartbeat has ultradian rhythm regulated by pacemaker-neuron membrane-potential changes by voltage-sensitive K-channels.
minute rhythm
Cycles can repeat every few seconds or minutes for sessile, burrowing, and boring animals. Protein regulates cell 12-minute growth cycles. Inositol-trisphosphate receptor regulates calcium release in C. elegans in fifty-second intervals.
day rhythm
People can live on 23-hour and 25-hour cycles.
development rhythm
Reaction-cycle superpositions cause development cycles, which have intervals from minutes to hours to days.
month rhythm
Biological rhythms can be monthly, for hormones and temperature. Sex-hormone levels vary over lunar month. Marine organisms feed or rest with lunar tides. Shore-living invertebrates typically have tidal cycles and long-term rhythms related to Moon cycles.
year rhythm
Biological rhythms can be yearly, for migrations and moods. Yearly rhythms include hibernation and estivation. Breeding seasons typically are yearly. In autumn, plants can die or start low-metabolism state {dormancy, plant}.
In mammals, Mop3 gene product is main component of 24-hour biological clocks {biological clock}|, in hypothalamus, eye, testis, ovary, liver, heart, lung, and kidney, which work by positive and negative feedback among proteins. Mammals can rest themselves according to environment. Mutant Mop3 requires homozygosity. Clock-gene product acts as a pacemaker in hypothalamus suprachiasmatic nucleus (SCN), which synchronizes other organ clocks. CLOCK, PER, and MOP3 proteins have PAS domains. Circadian rhythm affects albumin D-element-binding protein {mDbp}, which does not regulate circadian rhythm.
Neuron networks {central pattern generator} control breathing, walking, and swimming.
Body has daily activity patterns {circadian rhythm}|. Internal mechanisms for daily cycles have 24-hour cycles.
functions
Body temperature, activity, blood pressure, blood pulse rate, blood volume, hormone levels, eosinophil levels, ACTH concentration, cortisol concentration, magnesium concentration, calcium concentration, 17-hydroxycorticosteroid concentration, sodium concentration, potassium concentration, catecholamine concentration, and phosphate concentration vary over day.
functions: time of day
Labor is most frequent and T lymphocytes are most at 1 AM. Growth hormone and deep sleep are greatest at 2 AM. Asthma attacks are most frequent at 4 AM. Body temperature is lowest at 4:30 AM. Menstruation starts most frequently at 6 AM. Insulin, blood pressure, heart rate, and cortisol are lowest at 6 AM, but melatonin is highest. Blood pressure starts to rise at 6:45 AM. Hay fever is worst at 7 AM. Melatonin production stops at 7:30 AM. Heart attack and stroke are most frequent at 8 AM. Rheumatoid arthritis is worst at 8 AM. T lymphocytes are fewest at 8 AM. Bowel movements are most likely at 8:30 AM. Alertness is highest at 10 AM. Blood hemoglobin concentration is highest at 12 PM. Coordination is best at 2:30 PM. Respiration is fastest, reflexes are quickest, and hand grip is strongest at 3 PM to 3:30 PM. Body temperature, heart rate, and blood pressure are highest at 4 PM. Muscle strength is greatest at 5 PM. Urination is most frequent at 6 PM. Blood pressure is highest at 6:30 PM. Body temperature is highest at 6:30 PM. Sensitivity to pain is greatest at 9 PM. Melatonin production starts at 9 PM, induces sleep at night, and maximizes just before morning. Bowel movements stop at 10:30 PM. Allergic reaction is most frequent at 11 PM.
cycle
Light affects retinal ganglion-cell melanopsin receptors, which catabolize PERIOD (PER) and TIMELESS (TIM) protein complexes in cytoplasm. Six hours later, catabolism is complete and CYCLE and CLOCK proteins bind. Then combined proteins bind to PER and TIM genes in cell nucleus, to start transcription. Six hours later, PER and TIM proteins bind in cytoplasm to form complex that blocks binding of CYCLE and CLOCK in cell nucleus.
After several days {jet lag}|, travelers can adjust to new local time. Travel across time zones can cause disturbances in sleep, digestion, and daily activity rhythms, and disturbances are unpleasant, impair performance, and last several days.
People have 90-minute to 100-minute cycles {ultradian rhythm}|. Desire to eat, desire for sex, sleep phases, daydreams, dreams, alertness, stomach contractions, and instinctual drives in general have ultradian rhythms. Infants have 60-minute movement and inactivity cycles.
Animals can have twilight activity {crepuscular}|.
Animals can have daytime activity {diurnal}|.
Animals can have nighttime activity {nocturnal}|.
Yearly rhythm is deep suspended animation, with low temperature, slow heartbeat, and slow breathing, for summer {estivation}|.
Yearly rhythm is deep suspended animation, with low temperature, slow heartbeat, and slow breathing, for winter {hibernation}|.
Main ancient mammals {Tribosphenida} had special-shape molar teeth {tribosphenic molar}.
Duck-billed platypus and spiny anteater {monotreme}| (Monotrema) are small. Monotremes evolved by pedomorphism from juvenile cynodonts that matured quickly. Monotremes lay eggs. Eggs hatch, and infants drink milk from mammary glands. Duck-billed platypus finds buried molluscs and insects by electric potentials.
Mammals {Theria} can have live births, rather than eggs laid outside body, and mammary glands. Eggs develop inside body. Babies emerge in fetal stage, requiring care of young during gestation and after birth. Parental care causes adult-behavior imitation. Theria developed from monotremes. Theria include Eutheria and marsupials.
Kangaroo, koala, wombat, wallaroo, and opossum {marsupial}| (Marsupia) {pouched mammal} have embryos that develop inside body and bear live young, at fetal stage, that crawl to pouch on abdomen outside, to drink milk from mammary glands and develop. Marsupials care for young. Theria developed from monotremes. Marsupials came from early Theria.
small, Australia, long snout, claws, termite eater {banded anteater}.
plant eater, Australia and New Guinea, large hind legs, long thick tail {kangaroo}.
Australia, arboreal, gray, furry ears, no tail {koala}.
nocturnal, arboreal, long tail {opossum} (Didelphis) (Didelphidae).
small, fur, Australia, arboreal, long prehensile tail {phalanger}.
Australia, aquatic, egg-laying, duck-like flexible bill, web feet, gray fur {platypus} (Ornithorhynchus anatinus).
small, carnivorous, black, long tail {Tasmanian devil}.
kangaroo-like but smaller {wallaby} (Macropodidae).
burrowing, plant eater, Australia, medium size, dense hair, short tail, flat snout {wombat}.
In Cretaceous, 150 million years ago to 100 million years ago, small, nocturnal insect-eaters {placental mammal}| (Placentalia) evolved.
anatomy: placenta
Tissue {placenta}, in which mother blood vessels commingle with embryo vessels, surrounds embryo inside uterus, allowing food and waste exchange. This allows more embryo growth, by improving nutrition and respiration.
anatomy: senses
First Eutheria had large ears and good hearing. They had vibrissae and good smell sense. They had small eyes, on head sides.
anatomy: nervous system
First Eutheria had larger brains than same-size reptiles.
biology: signal
Mammals other than primates have 10 to 40 different signals.
biology: children
All Eutheria have live birth. Eutheria have fewer births per mother, birth at later stage, and more care of young. Culture transmission requires relatively few young. Adults must outnumber young to preserve culture.
types
The 23 placental-mammal orders include bats, carnivores, cetacea, edentates, hooved, insectivores, primates, proboscids, rodents, scienia, and simple hooved. Carnivores include cat, dog, bear, and seal. Edentates include sloth, anteater, and armadillo. Insectivores include hedgehog, insectivore shrew, and mole. Primates include tree shrew, lemur, tarsier, and monkey. Lemurs and tarsiers are similar.
clades
Placental mammals have four clades. Clade I {Afrotheria} includes elephants, manatees, aardvarks, and elephant shrews. Clade II {Xenarthra} includes sloths, anteaters, and armadillos. Clade III {Euarchontoglires} {Supraprimates} includes rodents, primates, flying lemurs, and tree shrews. Clade IV {Laurasiatheria} includes cetaceans, bats, carnivores, hedgehogs, insectivore shrews, and moles.
clades: evolution
Afrotheria was first. Afrotheria and Xenarthra, clades I and II, split 103 to 105 million years ago, in Cretaceous, perhaps from South America and Africa separation.
Early superorder {Boreoeutheria}, of clades III Euarchontoglires and IV Laurasiatheria, split from Xenarthra 84 to 95 million years ago.
Euarchontoglires and Laurasiatheria {Epitheria} split 60 million years ago.
clades: I Afrotheria
Afrotheria is in Africa and includes golden mole (Chrysochloridae), otter shrew/tenrec, elephant shrew/sengi (Macroscelidea), aardvark (Tubulidentata), hyrax (Hyracoidea), mantee/dugong (Sirenia), and elephant (Proboscidea).
Tenrec (Tenrecidae) and otter shrew (Potamogalinae) have cloaca and can look like shrews, hedgehogs, mice, or otters. Golden mole lives in south Africa, eats insects, burrows, and looks like moles. Golden mole and otter shrew/tenrec are order (Afrosoricida).
Elephant shrew or jumping shrew (Macroscelididae) has long nose and looks like shrews.
Hyrax, mantee/dugong, and elephant are clade (Paenungulata). Hyrax lives in Africa and Middle East, looks like rabbit or guinea pig, and ferments food in cecum {copraphage}.
clades: II Xenarthra
Xenarthra developed in South America and includes armadillo (Cingulata), anteater (Vermilingua), and tree sloth (Folivora), which have strange joints {xenarthra}. Anteater includes silky anteater, giant anteater, and tamandua. Tree sloth includes two-toed and three-toed sloths. Anteater and tree sloth are group (Pilosa).
clades: III Euarchontoglires
Squirrel, mouse, and other rodents (Rodentia); rabbit, hare, and pika (Lagomorpha); treeshrew (Scandentia); coluga (Dermoptera); and primates are superorder (Euarchontoglires) (Supraprimates).
Coluga (Cynocephalidae) or cobego or flying lemur can glide from trees and lives in southeast Asia. Coluga, primate, and treeshrew are order (Euarchonta).
Pika (Ochotonidae), rock rabbit, or coney is like hamsters and squeaks {whistling hare}. Rodents and lagomorphs are order (Glires).
clades: IV Laurasiatheria
Laurasiatheria developed in Laurasia and are bats, hedgehogs, cetaceans, even-toed ungulates, odd-toed ungulates, carnivores, and scaly anteaters.
Hedgehogs (Erinaceinae) live in Eurasia and Africa. Gymnures or moonrats live in southeast Asia. Hedgehogs and gymnures are early order (Erinaceomorpha).
Shrews (Soricidae) include white-toothed shrews, red-toothed shrews, and African white-toothed shrews. Moles (Talpidae) include Talpinae, Scalopinae, and Uropsilinae. Solenodons (Solenodontidae) look like large shrews, are insectivores, and live in Cuba and Haiti. Moles, shrews, and solenodons (Soricomorpha) are order.
Artiodactyla order of even-toed ungulates includes pigs, hippopotamus, camels, giraffe, deer, antelope, cattle, sheep, and goats. Cetacea order includes whales, dolphins, and porpoises. Cetaceans probably evolved from hippopotamus (Whippomorpha) (Cetancodonta). Cetaceans and even-toed ungulates are order (Cetartiodactyla).
Even-toed and odd-toed ungulates are a group.
Order (Pegasoferae) is in Africa and south Asia and includes pangolins or scaly anteaters (Pholidota), carnivores (Carnivora), bats (Chiroptera), and odd-toed ungulates (Perissodactyla), such as horses. Carnivores and scaly anteaters are group (Ferae).
Mammals accept that individuals can have authority, resulting in different ranks {dominance hierarchy}|. Animals in groups have ranks or roles, relatively dominant or subordinate. Older males typically dominate.
authority
Different species use different authority symbols.
hierarchy
All societies have status hierarchies and/or resource controls.
change
Primates form alliances based on obligations and contact, to gain higher rank. Ranks are always shifting. Dominance fights are not deadly. Animals can try to act differently than rank. Others must catch and punish offenders. Animals can try to deceive, but only higher apes seem to try to make others' beliefs be wrong.
effects
Dominance hierarchy causes hostility to strangers, maintains peace in society, decreases new behaviors, and causes threats from younger males toward older males.
factors
Dominance behaviors increase at breeding times. Dominance behaviors increase at higher population densities.
Only humans laugh {laughter, human}, but other mammals appear happy.
Fat layer {blubber}| can protect body from cold.
Insectivores have hands with opposing thumb across from fingers {grasping hand}|, which allows better grip and more hand-eye coordination.
Some whales have oil {spermaceti}.
Proboscids have long trunk {trunk}| from nose.
Proboscids have elongated incisor teeth {tusk}|.
Insectivores have eyes facing front {forward vision}|, rather than on side, allowing better vision and eye-hand coordination and more space for brain frontal lobes.
Some echolocating bats, like horseshoe bat, scan for sound and then focus sound using nose structures {nose leaves}.
Cats have mirror-like layer {tapetum} behind retina to reflect light back through retina.
Individuals at rank must know to do some things and not do other things {deontic reasoning}.
Individuals in society attend to and remember rule breaking and act on previous-situation knowledge {indicative reasoning}.
Proboscids {proboscid}| (Proboscidea) have nose trunk, thick and loose skin, and tusks. They include elephant, mastodon, and wooly mammoth. Elephants can make infrasonic sounds.
elephant, rhinoceros, hippopotamus {pachyderm}.
five-toes, trunk, thick skin, big ears, herbivorous {elephant}.
extinct elephant-like mammal {mammoth}.
extinct elephant-like mammal {mastodon}.
extinct elephant-like mammal {wooly mammoth}.
Manatees, dugong, and sea cows {Sirenia} are aquatic herbivores. Forelimbs are fins. They have no hind limbs.
cetaceous, tusks, flat tail, aquatic, herbivorous {dugong} (Halicore dugong).
plant eater, aquatic, Florida and Caribbean or West Africa, paddle front flippers, flat tail {manatee} (Trichechus).
dugong or manatee {sea cow}.
Edentates {edentate} (Edentata) have few or no teeth, eat insects, and include sloth, anteater, and armadillo.
burrowing, south Africa, stocky body, hair, large ears, long snout {aardvark} (Orycteropus afer) (Orycteropodidae) (Tubulidentata).
south Africa and Asia, horny scales, long snout {anteater} {giant anteater}.
burrowing, nocturnal, horny shell, omnivorous {armadillo} (Dasypodidae).
Asia and Africa Pholidota mammals {pangolin} can eat ants and termites with a sticky tongue. Pangolins have a long tail.
Tree sloths or three-toed sloths {sloth, mammal} have long claws and hang upside down from tree branches.
Bats {bat, mammal} (Chiroptera) can fly and glide. One-fifth of mammal species are bats.
anatomy
Bats have skin from long fingers to body and legs. They have elongated forearms and fingers, with short thumb. They have heel bone {calcar} to hold wing skin. Bats have long stylohyal bone from skull base to hyoid in throat and voice box. Bats have bulbous malleus.
location
Bats are everywhere except Antarctica.
size
Smallest is five centimeters, and largest is two meters.
food
Bats eat fruit, eat insects, eat meat, and suck nectar. Vampire bats lick blood.
echolocation
Bats use echoes from ultrasound-producing vocal chords to find and recognize objects by echolocation. All bats have echolocation, except Old World fruit bats, such as flying fox, which lost it.
Fruit bats and vampire bats send one frequency. Most bats vary sound frequency. They typically use downward sound, because echoes from nearby objects have lower frequency than from farther objects. Acuity is greatest for small frequency range. Bats adjust sent-signal frequency, so echoes are in that small frequency range. Most bats make sound pulses. Some bats use slow emission rate until they get close to something. Some bats protect ears during sound emission. Some bats can calculate approach speed using Doppler shift.
types
Bats are Old World (Desmodontidae) or New World bats.
types: Old World
Old World fruit bats, horseshoe bats, Old World leaf-nosed bats, false vampire bats, bumblebee bats, and mouse-tailed bats are Old World bats. Old World fruit bats are flying foxes.
types: New World
Slit-faced bats and sheath-tailed bats are group of New World bats.
New World leaf-nosed bats, leaf-chinned bats, fishing bats, smoky bats, disk-winged bats, New Zealand short-tailed bats, and sucker-footed bats are group of New World bats.
Evening bats, long-fingered bats, free-tailed bats, and funnel-eared bats are group of New World bats.
evolution
Bats are early Laurasiatheria. Bats flew before they could echolocate.
large, fruit eater {fruit bat} (Desmodontidae).
tropical, Americas, biting, blood drinker {vampire bat} (Desmodontidae).
Carnivores {carnivore, animal}| (Carnivora) have long, sharp-pointed canine teeth.
cats
Cats include lion, tiger, leopard, cheetah, cougar or mountain lion, and jaguar.
dogs
Dogs include hyena, wolf, and fox.
seals
Sea lion, seal or fur seal, and walrus live in arctic seas. Sea otter eats sea urchins and abalone.
other
Other carnivores are bear, otter, mink, weasel, and skunk.
white color
Transparency causes white-furred animals to look white.
large, claws, carnivorous, brown/black/white {bear, animal}.
large bear {black bear}.
bear {bruin}.
large bear {grizzly bear}.
Large bears {panda} can have white fur and black eye areas.
large white bear {polar bear}.
North America, lynx, spotted, red-brown, ear tufts, short tail {bobcat} (Lynx rufus).
mountain lion {catamount}.
large, fast {cheetah}.
large, tawny {cougar}.
cat {feline}.
large, tawny {jaguar}.
large, tawny with black spots {leopard}.
large, tawny {lion}. Males have manes.
medium size {lynx}.
medium size, tawny {mountain lion}.
small, nocturnal, Central America and South America, dark spots, brown {ocelot}.
large, tawny or black {panther}.
medium size, tawny {puma}.
large, extinct in late Tertiary, long upper canine teeth {saber-toothed tiger} {sabre-toothed tiger}.
large, white {snow leopard}.
large, tawny or white {tiger, mammal}.
cat-sized wild cat {wildcat, cat}.
fluffy {Maltese cat}.
short hair, no tail {manx cat}.
long white fur {Persian cat}.
short fur {Siamese cat}.
fluffy house cat {tabby cat}.
Civet family (Viverridae) has civet, genet, fossa, and binturong. Civets {viverrine} are small and cat-like.
raccoon-like, omnivore, Mexico and southwest USA, long bushy tail with black and white rings, nocturnal, musk {bassarisk} {civet cat}.
Asian viverrine, carnivorous {mongoose} (Herpestes).
Dogs {dog, animal} can understand 65 words or phrases and 25 signals or gestures. Dogs have 25 vocalizations and 305 different gestures but have no syntax or grammar.
Dog-like animals {canine, dog} (Canidae) have pointed conical teeth.
thick fur, arctic, brown in summer and white in winter {arctic fox}.
small wolf, west USA {coyote} (Canis latrans).
carnivorous, pointed muzzle, pointed ears, bushy tail {fox, mammal}.
dog-like, nocturnal, Africa and south Asia, eats carrion {hyena} (Crocuta) (Hyaenidae).
wild, medium size, scavenger {jackal} (Canis).
gray wolf {lobo}.
large, gray, forest, north North America {timber wolf} {timberwolf}.
northern, carnivorous, large, dog-like {wolf} {gray wolf} (Canis lupus).
large {Afghan, dog}.
large {Airedale}.
medium size {basset hound}.
medium size {beagle}.
large {bloodhound}.
large, sleek {borzoi}.
medium size {boxer}.
medium size {bulldog}.
small, thin {chihuahua}.
medium size {Cocker spaniel}.
large {collie}.
medium size {dachshund}.
large, spotted {dalmatian}.
large {Doberman}.
large {German shepherd}.
large {golden retriever}.
large {Great Dane}.
large {greyhound} {grayhound}.
large {Irish setter}.
large {Labrador retriever}.
large {mastiff}.
small {Pekinese}.
large {police dog}.
small {Pomeranian}.
medium size {poodle}.
large {retriever}.
large, sleek {saluki}.
large {Samoyed, dog}.
medium size {schnauzer}.
medium size {Scottish terrier}.
large {setter}.
large {sheep dog}.
medium size {Skye terrier}.
medium size {spaniel}.
Pomeranian or Samoyed {spitz}.
large {St. Bernard}.
medium size {terrier}.
ferret, mink, otter, raccoon, skunk, weasel, and wolverine {mustelid} (Mustela).
burrowing, claws {badger, mammal}.
Northern weasels {ermine} (Mustela erminea) can have black tail tips and dark brown fur in summer and white fur in winter.
weasel, North America {ferret, mammal} (Mustela nigripes).
slender, weasel-like, arboreal, larger than weasel {marten}.
small, short-legged weasel {mink}.
freshwater, web feet, claws {otter}.
skunk {polecat}.
North America, nocturnal {raccoon} (Procyon lotor).
north Europe and Asia, soft dark fur {sable, mammal} (Martes zibellina).
marine otter {sea otter}.
medium size, New World, bushy tail, black fur, white lengthwise stripes {skunk} (Mephitis).
small, short legs, long body, long neck, brown {weasel}.
burrowing, northern forest {wolverine} (Gulo gulo).
Sea lion, seal, and walrus {pinniped} have backward hind limbs.
swimmer and diver, marine, hind limbs turned backward {seal}.
north Atlantic Ocean, earless, seal, overhanging snout {elephant seal} (Mirounga angustirostris).
large ear, marine, seal, long neck, long limbs {sea lion} (Zalophus californianus).
northern, marine, ivory tusk, tough hide, thick blubber {walrus}.
Dolphins (Sotalia) (Delphinus) (Tursiops) and whales {Cetacea} live in ocean and have blubber.
limbs
Forelimbs are fin-like. They have no hind limbs.
respiration
Cetaceans have one or two blowholes on head top.
teeth or baleen
Some Cetacea (Odontocetes) have teeth: sperm, pilot, and beluga whales, and dolphins and porpoises. Some Cetacea (Mysticetes) have baleen: blue and fin whales. Extinct ancestors belong to Archaeocetes.
whales
Sulfur-bottom whale is 150 tons and 35 meters long. Narwhal has long horn. Humpback whale, finback whale, gray whale, and blue whale are other whales.
dolphins
Dolphin has directional sonar, useful up to mile. Porpoise is like dolphin. Orca or killer whale is large dolphin. Dolphins shed soft flaky skin every two hours.
evolution
Cetacea evolved from artiodactyls.
smooth skin, pointed snout, tail flips up and down, makes sounds {dolphin} (Tursiops) (Delphinidae).
rounded forehead, beak, north Atlantic and Mediterranean {bottle-nosed dolphin} (Tursiops).
black and white, largest dolphin {orca} {killer whale}.
smaller than dolphin, blunt snout {porpoise} (Phocaena) (Lagenorhynchus).
Whales {whale, mammal} are baleen or toothed whales.
whale {leviathan}.
small, Arctic whale, male {narwhal} (Monodon monoceros). Male has large long twisted elongated tooth.
largest toothed whale {sperm whale}. Head cavity contains spermaceti and oil.
marine, large, two blowholes, filter feeder {baleen whale} (Mysticeti). Rorqual whales are finback whale, blue whale, and humpback whale. Other whales are gray whale, right whale, and Sei whale. Elastic, horny material makes fringed plates {baleen} {whalebone} down from upper jaws.
baleen whale, arctic {right whale}.
Large marine filter-feeder baleen whales {rorqual whale} include finback whale, blue whale, and humpback whale.
large, baleen whale, rorqual whale {blue whale}.
baleen whale, large, flat head, throat furrows, rorqual whale {finback whale}.
baleen whale, rorqual whale {humpback whale}.
Simple hooved mammals {simple hooved mammal} (Artiodactyla) have hooves with even number of digits. They are herbivores. They include camel, hippopotamus, whales, cow, sheep, pig, giraffe, deer, wildebeest, antelope, and bighorn sheep. They include ruminants. Hippos evolved from swamp-dwelling anthracotheres. Artiodactyla have hooves and were formerly in Ungulata order.
Artiodactyla and Perissodactyla have hooves and formerly were an order {ungulate}| (Ungulata).
Ferungulates {ferungulate} are simple hooved mammals like cow and whale, hooved mammals like horse and rhinoceros, and carnivores like cats and seals.
Mammals {ruminant} (Ruminantia) can have stomachs with four parts and chew regurgitated cud. They have hooves with even-numbered toes. Males have horns. They include cows, sheep, goats, deer, and giraffes.
deer, elk, moose, reindeer, and caribou {cervid}| (Cervidae).
cow, buffalo, sheep, goat, and antelope {bovid}| (Bovidae).
Africa, ruminant, long neck, long legs, tan with brown spots {giraffe} (Giraffa camelopardalis) (Giraffidae).
very large, thick skin, herbivorous, river, tropical Africa {hippopotamus} (Hippopotamus amphibius) (Hippopotamidae).
brown or gray, two-toe hooves, unbranched horns, fast, Africa and Asia {antelope}.
African antelope {eland}.
small, antelope, Africa and Asia, spiral horns, large eyes {gazelle}.
large, Africa, antelope, horns, long tufted tail {gnu}.
America {pronghorn antelope}.
South Africa, gazelle, springs {springbok}.
gnu {wildebeest}.
one or two humps, long neck, ruminant, Asia {camel, animal} (Camelus).
llama {alpaca llama}.
two humps, central Asia {Bactrian camel}.
single hump, large, even-toed, ungulate {dromedary camel} (Camelus).
small camel-like mammal {llama, animal} (Lama) (Camelidae).
domesticated cattle {cow, animal} (Bovidae).
baby cow {calf, cow}.
cow being herded {dogie}.
young cow {heifer}.
milk cow {milch cow}.
male cattle {steer}.
domesticated, meat {Aberdeen Angus cattle}.
buffalo {bison}.
large-shouldered bull for bull riding {Brahma bull}.
large, shaggy, brown, bison, North American plains {buffalo, mammal} (Bison bison).
domesticated, milk {Guernsey cow}.
domesticated {Hereford cattle}.
domesticated, milk {Jersey cow}.
domesticated, meat {longhorn cattle}.
arctic, bovid, thick coat {musk-ox}. It is not an ox.
Asian buffalo, typically domesticated draft animal {water buffalo, animal} (Bubalus bubalis).
adult castrated bull {ox} (Bos), or cattle-family draft animal.
large ox, shaggy hair, ox, central Asian mountains {yak, mammal} (Bos grunniens).
Asian and east African ox {zebu} can have a large hump and loose dewlap hanging under throat and neck.
Deer {deer, animal} are similar to Bovidae, but male has solid deciduous horns {antler}.
male deer {buck}.
female deer {doe}.
North America, arctic, same as reindeer {caribou}. Both sexes have large antlers.
largest deer, north Europe, broad antlers on bulls, same as moose {elk}.
male deer or male red deer over five years old {hart}.
female red deer {hind}.
largest deer, north America and Canada, broad antlers on bulls, same as elk {moose} (Alces alces).
Europe and Asia, arctic, same as caribou {reindeer}. Both sexes have large antlers.
adult male deer {stag, mammal}.
large, North America, large and branched antlers {wapiti}.
ruminant, beard, straight horns, related to sheep {goat, animal}.
goat {Angora goat}.
male goat {billy goat}.
large, ridged, curved-over horns {ibex}.
young goat {kid}.
female goat {nanny goat}.
short legs, cloven hooves, bristly hair, cartilaginous snout {pig, animal} (Suidae).
young pig {shoat}.
female pig {sow}.
pig {swine}.
wild pig, narrow body, tusks, snout bristles {boar}.
pig {hog}.
Africa, face warts, large tusks {warthog}.
boar {wild boar}.
wool, horns, ruminant, related to goat {sheep}.
female sheep {ewe}.
young sheep {lamb, mammal}.
male sheep {ram}.
north Africa {aoudad} {Barbary sheep}.
light color, large curled horns, Canadian mountains {bighorn sheep}.
Hooved mammals {hooved mammal} (Perissodactyla) have hooves with odd number of digits, are herbivores, and include horse, zebra, tapir, and rhinoceros.
very large, herbivorous, ungulate, southeast Asia and Africa, thick skin, one or two snout horns {rhinoceros} (Rhinocerotidae).
herbivorous, related to rhinoceros, large, nocturnal, ungulate, tropical {tapir}.
solid hoof, herbivorous, short hair, mane, long tail {horse} (Equus caballus) (Equidae).
horse used in war {charger}.
young horse {colt}.
horse used for racing {courser}.
farm horse {dobbin}.
horse used to pull load {draft horse}.
young female horse {filly}.
first-year horse {foal}.
emasculated horse {gelding}.
female horse {mare}.
horse used for riding {mount, horse}.
old horse {nag}.
Horse with large brown patches or black and white patches {pinto} {paint, horse}.
small horse {pony, horse}.
riding horse {saddle horse}.
male horse {stallion}.
horse used for riding {steed}.
strong horse {wheelhorse}.
first-year horse {yearling}.
medium size, various colors {appaloosa horse}.
large {Arabian horse}.
small horse-like mammal, donkey or wild ass {ass, horse-like}.
small donkey {burro}.
large horse used to pull wagons {clydesdale}.
domesticated ass {donkey} (Equus asinus).
female-horse and male-donkey sterile son or daughter {mule, mammal}.
small feral horse, North American west {mustang}.
gold, white mane, white tail {palomino}.
small, stocky, short head, small muzzle, gold, white mane, white tail {quarter horse}.
small horse {Shetland pony}.
horse-like, Africa, black and white vertical stripes {zebra}.
Burrowing domesticated rodents {rabbit} (Leporidae) can have long ears and short tails.
European rabbit {coney}.
rabbit {cottontail}.
long ear, larger than rabbit, divided upper lip, long hind legs {hare} (Lepus).
large hare, west North America {jackrabbit}.
northern hare {snowshoe hare}.
Rodents {rodent, animal}| (Rodentia) have sharp, chisel-like incisor teeth. They include squirrel, chipmunk, beaver, rat, mouse, porcupine, hamster, guinea pig, and chinchilla.
large, aquatic, thick brown fur, webbed hind feet, flat tail {beaver} (Castor).
squirrel-like, South American mountains, silver-gray fur {chinchilla} (Chinchilla laniger).
small, striped, ground, squirrel {chipmunk} (Tamias) (Eutamias).
small, Asian, burrowing, desert, long fur, light color, long hind legs {gerbil} (Gerbillus).
burrowing, small, short tail, furry cheek pouches {gopher}.
woodchuck {ground hog}.
small, short ears, no tail {guinea pig, animal} (Cavia).
small, Europe and Asia, large cheek pouches, short tail {hamster} (Mesocricetus auratus) (Cricetinae).
large, insectivore, sharp erectile bristles {hedgehog} (Erinaceidae).
small, short tail, furry, moves in group {lemming} (Lemmus).
coarse fur, burrowing, short legs, small ears, short bushy tail, thick body {marmot} (Marmota).
eusocial, tropical {mole-rat} (Bathyergidae).
small size, long hard tail {mouse, mammal}.
large, flat scaly tail, aquatic {muskrat}.
small, North America, nest filled with small items {pack rat} (Neotoma).
large, sharp erectile bristles {porcupine} (Erethizon dorsatum) (Erethizontidae).
North America, prairie, burrowing, squirrel, light brown, warning call, large colony {prairie dog} (Cynomys).
medium size, long hard tail {rat}.
arboreal, long bushy tail {squirrel} (Sciurus).
red-brown, burrowing, north and east North America, short legs, thick body, marmot {groundhog} {woodchuck} (Marmota monax).
150 million years ago to 100 million years ago, mammals {insectivore}| (Insectivora) evolved that ate insects. Early ones {primitive insectivores} look like tree shrews.
vision
Insectivores have forward vision, with eyes facing front rather than on side, allowing stereoscopic vision and space for larger frontal lobes.
hand
Insectivores have grasping hands, with opposing thumb across from fingers, for more eye-hand coordination and precise hand and arm movements.
evolution
Primitive insectivores evolved from placental mammals. Primates evolved from primitive insectivores.
types
Insectivores include mole, hedgehog, and shrew.
Mammals {mole, mammal} (Phacoschoerus) (Talpidae) (Chrysochloridae) can live underground, be nocturnal, and have front digging paws. Star-nosed moles have quickly moving touch organ in front. 22 arms have 25,000 Eimer's organs, which are similar to Pacinian corpuscles and contain touch receptors. Free-nerve-ending touch receptors are for vibration and contact. Merkel-cell touch receptors are for pressure. Both are in all mammals. Moles have free nerve endings in a circle, used for detecting texture. The most-sensitive arm matures first and is larger in embryos. Skin surfaces probably had such strips in mammal predecessors.
Small mouse-like mammals {shrew, primate} {tree shrew} (Soricidae) can have a long pointed snout.
Insectivore mammals {primate} include prosiminan, New World monkey, Old World monkey, ape, and human. Primates can learn new behaviors, are curious, are vigilant, have short attention span, easily distract, and have many stereotypical activities that last for long periods.
evolution
Primates arose from primitive insectivores in early Eocene, 65 million years ago.
Strepsirhines arose 60 million years ago. They include loris, lemur, and galago.
Haplorhines {anthropoid apes} arose 55 million years ago. They include tarsiers, bush babies, monkeys, apes, and humans.
Prosimians include Strepsirhines and early Haplorhines.
Haplorhine monkeys became Old World monkeys {Catarrhini} and New World monkeys {Platyrrhini} 40 million years ago. New World monkeys include spider monkeys. Old World monkeys (Cercopithecidae) include rhesus monkeys, capuchins, macaques, and baboons.
Old World monkeys and gibbons (Hylobates) separated 30 million years ago.
Gibbons and anthropoid apes (great apes) (hominids) (Hominidae) separated 17 to 19 million years ago. Anthropoid apes include Pongo pan with orangutans, Gorilla with gorillas, Pan troglodytes with chimpanzees, Pan paniscus {pygmy chimpanzee}, and Homo with humans. Note: An older classification put humans into a hominid family (Hominidae) and all hominids except humans into pongid family (Pongidae).
Orangutans began 16 million years ago.
Gorillas separated from orangutans 8 to 9 million years ago.
Chimpanzees separated from gorillas 6.2 to 6.7 million years ago.
A family (hominins) (Homininae) with genuses Australopithecus, Paranthropus, Ardipithecus, and Homo began 6 million years ago.
Genus Homo began 2 million years ago.
food
Primates were predators, but some are now savanna vegetarians.
society
Primates live in territorial groups of 100 or less, with males dominating females. The six species vary greatly in social organization. Primates have long maternal care of young. All primate societies have aggressive dominance systems, scaling in behavior, socialization, matrilineal social organization, and game playing.
society: signals
Social organization depends on signaling. Primates have rudimentary vocal-signal languages. For example, gibbons have 12 standardized, meaningful calls.
hands and feet
Primates can have prehensile hands and feet. They have opposing thumb and can have opposing toe. They have nails instead of claws. They have grasping hands. They developed better hand movements and hand-eye-body coordination.
movement control
In primates, posterior parietal lobe is for movement control.
DNA transposition
Primate DNA-transposition rate is lower than mice rate.
brain
Neocortex has enlarged occipital and temporal lobes.
senses
Primates have olfactory systems similar to those in other placental mammals.
senses: vision
Primates have large eyes in front in large bony sockets. They have fovea high ganglion-cell concentration.
Optic tectums see only visual-field contralateral half, unlike other vertebrates. Primates integrate binocular input in optic tectum, laminated dorsal lateral geniculate nucleus, and primary visual cortex maps.
Primates have dorsolateral visual area (DL), adjacent to medial temporal lobe. They have fusiform gyrus on occipital-lobe underside.
Nocturnal visual predators, such as owls and cats, orient body so prey is in front and then move forward, using forelimbs and jaws to attack. Stereoscopic vision detects prey distance and discriminates camouflaged prey from background.
Primates have lateral prefrontal cortex {lateral prefrontal cortex}, but lower mammals do not.
Strepsirhines have furless, moist, mucous tissue {rhinarium, primate} with cleft down middle between upper lip and nostrils, as in most mammals.
Alu repeats {DNA repeat, primate} are only in primates, repeat million times in different locations, are 10% of DNA, have internal promoter, and are similar in sequence to ribosome gene.
Prosimians {prosimian}| include tarsiers, bush babies, lorises, lemurs, and galagos. They are small, live in fine-branch niches, eat fruit and/or insects, have short muzzles and short noses, have fingernails, have large and widely spaced eyes, and have more than 32 teeth.
smell
They have scent glands, like most primitive mammals, and use scent-marking behaviors for social communication.
vision
Optic tectums receive only from visual-field left or right half, whereas in lower mammals optic tectums receive from left and right.
evolution
Prosimians developed from primitive insectivores.
First primate family {Strepsirhines} includes lorises, lemurs, and galagos but not bush babies or tarsiers. They have furless, moist, mucous tissue with cleft down middle between upper lip and nostrils {rhinarium, Strepsirhines}, as in most mammals. They have simple social organization. In Strepsirhines and primitive mammals, main input to amygdala is from olfactory bulb.
Second primate family {Haplorhines} includes tarsiers, monkeys, apes, and humans. It has furry rhinarium {rhinarium, Haplorhines} and movable upper lip for facial expressions. It uses gestures and has complex social organization. In Haplorhines, main input to amygdala is from visual inferotemporal cortex.
moist nose {bush baby}.
Madagascar, arboreal, mostly nocturnal {lemur} (Lemuridae).
nocturnal, Indonesia, dry nose {tarsier}.
Monkeys {monkey} include New World monkeys and Old World monkeys. Monkeys evolved from prosimians. First monkeys were like New World monkeys.
ape or monkey {simian}.
Smaller monkeys are diurnal and eat leaves {folivore}.
Monkeys can be larger, be active day and night, and eat fruit {frugivore}|. Primate frugivores have larger brains with more neocortex than same-size primate folivores. Fruit supply and type always varies, because different plants bear fruit at different times and locations in tropical forest. Frugivores require better visual perception and memory.
Marmosets, tamarins, squirrel monkeys, and spider monkeys {New World monkey}| were first monkeys.
evolution
New World monkeys came from Africa to South America on floating vegetation. Parapithecus was ancestor of Old World monkeys.
habitat
New World monkeys live in trees.
anatomy: tail
New World monkeys have prehensile tails.
anatomy: nostrils
New World monkeys have upward-pointing nostrils (Platyrrhini) and broad flat noses.
brain: striate cortex
Primate striate cortex can differ from motor cortex {giant Betz cell} in laminar organization, cell number, cell types, and general connectivity patterns.
brain: ventral premotor area
Ventral premotor area aids visually guided hand movements and learning by watching.
brain: Wernicke's area
Monkeys have Wernicke's area at vision, audition, and somaesthetic cortical junction.
senses
In monkeys, object perception uses one sense pathway involving all senses. Humans use this pathway only at birth.
senses: vision
Fovea allows sharp vision in visual-field center. Brain pathway for shapes and brain pathway for movement and contrast evolved. Brain area V1 has blobs and interblobs. V4, V8, and MT brain areas evolved.
self
Tamarin monkeys are curious about their bodies and movements they see in mirrors, unlike cats and dogs. Monkeys can have sense of self [Hauser, 2000].
mother
Monkeys normally cling to mothers for contact and security. If mother was absent from monkey infants, infants stayed afraid of strange objects and did not explore them. Later, the monkeys had sexual and mothering problems. If monkeys have no play and no mother, they have more aggression and wariness. Baby monkeys cling to cloth monkeys as mother substitutes [Harlow and Harlow, 1949].
suffering
Monkeys can suffer, because they can do something about conditions that make them suffer [Povinelli, 1998].
signal
Vervet monkeys make different alarm calls for eagles, leopards, and snakes and use grunts in social interactions [Cheney and Seyfarth, 1990] [Seyfarth and Cheney, 1992].
Putty-nosed monkeys make alarm calls for crowned eagles that make other monkeys stand still. Calls for leopards cause them look at ground. They can combine the calls to signal group to leave place.
Marmosets, tamarins, squirrel monkeys, and spider monkeys live in trees {arboreal}| and have prehensile tails.
Small monkeys {marmoset} have soft fur, come from South America and Central America, and have claws instead of nails.
monkey {rhesus monkey}.
monkey {spider monkey}.
monkey {squirrel monkey}.
African monkeys {Old World monkey} include capuchin, macaque, baboon, and mandrill. Macaques include rhesus monkeys (Macaca mulatta) and crab-eating monkeys (Macaca fascicularis). Old World monkeys are arboreal.
nostrils
Old World monkeys (Cercopithecidae) have down-pointing nostrils and short narrow noses (Catarrhini), allowing better vision and more space for frontal lobes.
sitting pads
Old World monkeys sit upright on sometimes colored buttock sitting pads.
tailless
Old World monkeys have no prehensile tails.
reproduction
Old World monkeys have sexual dimorphism and male rivalry.
digestion
Old World monkeys ate fruit and had 32 teeth.
senses
Short narrow noses had nose openings pointed down (Catarrhini), for better vision and more space available for frontal lobes. They had three cone types and full color vision. Postorbital septum isolated eyes from temporal muscles.
evolution
Old World monkeys differentiated from New World monkeys in Oligocene epoch.
types
Xenopithecus was ancient Old World Monkey. Aegyptopithecus was Old-World monkey in Fayum deposits in Egypt.
Apes {ape, animal} came from Old World monkeys.
cognition: causation
Apes understand that acting on one object can cause connected-object motion.
cognition: deception
Apes practice deception by distracting attention, so they can steal food or mates [Byrne and Whiten, 1988] [Whiten and Byrne, 1997].
cognition: laughing
Only humans laugh, but young chimpanzees puff air when they play, similar to laughing. Apes can also appear happy. Chimpanzees smile when submitting, but not from happiness. Perhaps, laughter is for alliance making.
cognition: mirror
Some apes can touch body spots they see in mirrors. Some apes seem to recognize themselves in mirrors after a while. Chimpanzees, orangutans, bonobos, and humans over two years old can use their reflections in mirrors to perceive body and direct actions. They can recognize themselves and have sense of self. Gorillas, monkeys, and children less than two years old do not [Gallup, 1970] [Gallup, 1998]. Chimps, bonobos, and orangutans can recognize themselves in mirrors immediately or after several-days experience, but gorillas, baboons, and most other primates cannot [Napier, 1976] [Napier, 1977].
cognition: play
Apes like to play.
cognition: self
Chimpanzees have no sense of self and no consciousness of mental states, though they can inspect their bodies using mirrors [Heyes and Galef, 1996] [Heyes, 1998].
cognition: suffering
Apes can suffer, because they can do something about conditions that make them suffer.
biology: parental care
Apes have parental care over long childhoods.
biology: palm walking
Apes used palm walking, not knuckle walking as in monkeys.
biology: reflex
Adult apes have Babiniski reflex, to grasp tree branches with toes.
biology: one sense pathway
In apes, object perception uses one sense pathway involving all senses, as humans do at birth.
biology: pheromone and sex
Sex-hormone-derived pheromones are in skin secretions [Savic et al., 2001] [Savic, 2002] [Sobel et al., 1999].
biology: pheromone receptivity
Baboons secrete female pheromones during receptivity. Community living can synchronize ovulation through olfactory signal. Small pheromone amounts work [Gangestad et al., 2002] [McClintock, 1998] [Schank, 2001] [Stern and McClintock, 1998] [Weller et al., 1999] [Pantages and Dulac, 2000].
biology: serotonin reuptake
Anthropoid apes have different promoter sequence for serotonin reuptake transport gene than humans do.
biology: evolution
Proconsul was lesser ape and was hominid ancestor. It was ape-like in shoulder, elbow, cranium, and teeth dentition. It was monkey-like in long trunk, backbone, pelvis, arm, and hand. At least four species weighed from 10 to 80 kilograms.
communication: sign language
After four years of training, the chimpanzee Washoe acquired over 100 American Sign Language signs. It heard no other language. Some signs were for general classes, rather than just objects and events. Some signs changed or extended. Washoe used sign order. Washoe substituted signs with similar meanings or shapes.
However, no primates develop signing themselves. Humans have to teach them. Humans cue chimpanzees to make signs, and chimpanzees sign to get rewards. Chimpanzees sign to each other socially but not for rewards [Gardner and Gardner, 1969].
communication: signals
Chimpanzees and gorillas cannot learn to use expressions with interruptions. Animal communications always repeat. Behavior, display, or signal redundancy and ritualization increase communication efficiency. Animals often use opposite signals, such as high and low, or loud and soft, for opposite intentions or behavior. Animals can modify signals in different contexts, but they do not rearrange symbol order deliberately nor assign meaning to signal order.
communication: symbol
Apes have 150 to 200 non-linguistic symbols, such as facial expressions, danger and location calls, courtship rituals and displays, grooming, group or family signals, and personal communication between individuals. Humans have 150 to 200 non-linguistic symbols.
communication: word
The bonobo Kanzi used and understood 150 words, typically to express desires or refer to present objects. Learning was instrumental association, with no grammar. Perhaps, it was not referential [Savage-Rumbaugh, 1986].
society
Ape societies have 10 to 100 animals.
Human ancestors {missing link}| can fill fossil gap between apes and humans.
Male orangutans have cheek pads {flanges}.
Australopithecus were not always robust {gracile}|.
Dryopithecus had face that tilted down {klinorhynchy, face}. Orangutans, gibbons, and siamangs have airorhynchy.
Orangutans, gibbons, and siamangs have faces that tilt up {airorhynchy, face}. Dryopithecus had klinorhynchy.
Lesser apes {ape, lesser} {lesser ape} {pongid}| {hylobatid} (Hylobates) separated from Old World monkeys [-22000000]. Proconsul in Kenya, Afropithecus in Kenya, Kenyapithecus in Kenya, and Morotopithecus in Uganda lived in early Miocene. Early lesser apes were like siamang and gibbon, except they walked on all fours on branch tops. Apes have broad chests and large brains. They weigh from 3 to 80 kilograms.
development
Apes grow more slowly than monkeys.
reproduction
Apes reproduced less than monkeys.
skeleton
Apes have more flexible hips, shoulders, wrists, ankles, hands, and feet than monkeys.
digestion
Some apes eat leaves. Some apes eat fruit and nuts.
tailless
Having no tail allows sitting, more sexual intercourse positions, and new spinal shapes.
posture
Apes have semi-erect posture. Apes can hold arms above heads and so hang, using opposing thumbs.
face
Apes have movable upper lips, allowing facial expressions.
ape, small, arboreal, muzzle, southeast Asia and East Indies, long arms {gibbon} (Hylobates).
ape, large, black, terrestrial, bare colored buttocks, Africa and Asia {baboon} (Papio) (Cercopithecidae).
west Africa baboon {mandrill}.
Apes {great ape} evolved.
skeleton
Great apes have shoulder blades on back, while lesser apes have shoulder blades on sides. Great apes have shallow ribcages, while lesser apes have deep ribcages. Great apes have flexible hips, while lesser apes have restricted movement.
skeleton: spine
Great apes have short stiff S-shaped spines with two curves, rather than straight or single-curve spines, for more upright posture. S-shaped spine is more flexible, allows running, and aids balance. Great-ape vertebrae projections point out back, while lesser-ape vertebrae projections point to side.
arm
Great apes have big hands, while lesser apes have small hands. Great apes can make rapid arm movements similar to hammering, clubbing, and throwing. Great apes can extend elbow joint fully, while lesser apes cannot make arm straight. Great apes have arms longer than legs, while lesser apes have equal lengths.
tools
Great apes make and use tools.
hunting
Great apes hunt, but not with tools.
society
Great apes live in societies, which increase opportunities for learning, experience, and knowledge.
senses
Great apes do not correlate senses.
evolution
Apes and great apes split 15 million years ago. Great apes evolved from Proconsul-like lesser apes.
Pongo pygmaeus {orangutan} are great apes, are solitary, have no tail, live in trees in nest, and are in Borneo and Sumatra rain forests. They are safe in treetops. They can live for 60 years.
sex
Males become mature at 12 to 14 years, are twice as big as females, have flanges, have throat sac for yelling {long call}, and have long orange hair. Puberty is at age 7 to 9. If group has dominant male, young males can stay pubescent.
tools
In swamp forests of Sumatra and Borneo, where food is abundant, they can learn to use tools at 7 years old.
Anthropoid apes {anthropoid ape} (hominids), such as gorillas and chimpanzees, differentiated from apes in hands, feet, arms, and legs.
types
Propliopithecus was first anthropoid ape and direct ancestor of all hominids.
hand
Anthropoid apes have grasping hands.
walking
Anthropoid apes walk upright, requiring mechanisms for balance, allowing farther and greater lateral vision, and requiring learned gait. Anthropoid apes have wider territory and shared or secured territory.
habitat
Gorillas live on ground, and others live in trees.
communication
Anthropoid apes communicate, using dozens of meaningful sounds, about objects but do not have mental states.
vision
Color vision can see ripe fruits in forest and recognize faces.
brain
Delay system in frontal lobe between senses and motor nerves possibly allows decision-making. Anthropoid apes are curious, reason, have emotions, have social instincts, and imitate. Great apes have neurons in anterior cingulate that have apical dendrite and dendrite near axon and look like spindles.
largest anthropoid ape, black, terrestrial, vegetarian, equatorial West Africa {gorilla} (Gorilla gorilla).
Genus Pan apes {Pan, ape} split from gorillas and was like chimpanzee, pygmy chimpanzee, or bonobo. Pan apes weigh 30 to 60 kilograms. They eat fruit and have large canine teeth with thin enamel. They have long arms and legs. They are arboreal. They are knuckle walkers on all fours. They are sexually dimorphic and have polygynous social structure. They are hairy.
pygmy chimpanzee {bonobo}|.
Chimpanzees {chimpanzee} are great apes. Chimpanzees can communicate using complex sign or symbol systems and have more than 30 meaningful vocalizations. Chimpanzees can cooperate. Chimpanzees can deceive others. Chimpanzees have concept of self. Chimpanzees use and make tools. Given puzzles, they manipulate pieces, even without reward.
Hominins {hominin}| (Homininae) vary from anthropoid apes (great apes) (hominids) (Hominidae) in locomotion, hands, tools, sight, sociability, and language.
evolution
Hominins differentiated from Pan ancestors six million years ago.
habitat
Australopithecus lived in savannas, rather than forests, and used more animal food than apes. Perhaps, necessity to eat seeds and nuts aided hand evolution. Hominins developed environments, with more energy available for brain maintenance. Free-ranging energetic environments and multiply skilled bodies allowed energy-intensive cortex to vary, grow, and integrate senses.
anatomy: tailless
Hominins had no tail, allowing more variations in intercourse position, sitting, and spinal shape.
anatomy: face
Hominins have nosebridges and nose tips, jutting chins, short canine teeth, and lips with median furrow that rolls outward.
anatomy: arm
Hominins have shorter arms than great apes and throw accurately.
anatomy: foot
Hominins have feet that arch across and lengthwise. They do not have opposed big toes.
anatomy: hair
Hominins are relatively hairless.
anatomy: posture
Hominins have erect posture.
reproduction
Hominins mature sexually earlier than other great apes, as measured by teeth eruption.
senses
Sense integration allows tracking individuals that are not present, mapping environments, and remembering.
nervous system
Brains were two to three times bigger than great-ape brains.
communication
Hominins blend the dozen meaningful ape sounds to produce new sounds related to objects far away in time or place. They possibly use nouns, verbs, and modifiers with simple syntax. They recall memories.
communication: larynx
Larynx became lower and opened throat space {supralaryngeal space}, which allows more speech sounds.
Varied and separated habitats isolated four hominin species {Australopithecus} {australopithecenes}: first Australopithecus afarensis, then gracile Australopithecus africanus, robust Australopithecus robustus, and robust Australopithecus boisei.
habitat
Australopithecus lived on ground in woodlands and savannas. Perhaps, it slept in trees or cliffs.
digestion
Australopithecus ate vegetables and later meat and had ape-like dentition.
behavior
Australopithecus foraged.
tools
Australopithecus used pumice flakes and stone choppers as rooting tools.
arm
Australopithecus had large hands, long fingers, and short arms.
walking
Australopithecus was bipedal, had short stride, ran slowly, and had no knuckle walking.
development
Maturation time was short.
brain
Brain was one-third modern human size.
Early hominins {Australopithecus afarensis} were gracile, weighed 35 kilograms, and were one meter tall.
evolution
Australopithecus afarensis came from Australopithecus anamensis and was Australopithecus-gahri ancestor.
tools
Australopithecus afarensis used pebble tools.
climbing
Australopithecus afarensis had climbing adaptations in fingers, hands, wrists, elbows, and shoulders, with long arms and short legs.
walking
Australopithecus afarensis was bipedal with full striding gait, putting body weight over one leg while other leg moved. It had arched feet and non-opposable big toes, like modern human feet. It had knee valgus angle. It had great pelvic width. Perhaps, width was for pelvic rotation in walking. It had short, broad, backward, extended, iliac blades.
hand
Australopithecus afarensis had shorter thumbs.
society
Perhaps, Australopithecus afarensis had large kin-related and many-male groups, with some non-kin females.
digestion
Australopithecus afarensis had large and flat cheek teeth, suggesting fruit and leaf diet.
face
Australopithecus afarensis had big faces.
brain
Australopithecus afarensis had 400-cc brains, with 3.1 encephalization quotient. It had forward-placed and downward-directed foramen magnum, indicating head was upright on spine. Bipedalism led to an enlarged occipital-marginal-sinus system, which forced new blood hydrostatic pressures on vertebral venous plexus.
Second Australopithecus {Australopithecus africanus} [first found 1924] was gracile, weighed 35 kilograms, and was four feet tall.
evolution
Australopithecus africanus came from Australopithecus anamensis and was Australopithecus-robustus ancestor.
habitat
Australopithecus africanus lived in grasslands, not forests, and probably lived in one place for long periods. Perhaps, it used windbreaks.
hunting
Australopithecus africanus hunted animals, ate raw meat, cut skins, smashed bones, and took meat home.
tools
Australopithecus africanus selected stones, carried them home, and chipped to make hand-held choppers.
hand
Australopithecus africanus had flattened fingertips.
spine
S-shaped spines, with two curves, allowed more back flexibility and so more upright walking, more erect posture, faster running, and better balance. Upright posture allowed wider and farther vision.
digestion
Australopithecus africanus had no canine teeth and lean jaws, like humans, reflecting different diet.
brain
Australopithecus africanus had low skulls, with 500-cc to 800-cc brains. Many anastomotic channels with emissary veins near foramen magnum take blood to vertebral venous plexus. Perhaps, expanded neocortex frontal lobes allowed improved memory, spatial orientation, temporal orientation, and multisensory abilities.
Paranthropus hominins {Australopithecus robustus} (Paranthropus robustus) were not on human line, were 45 kilograms, were heavyset, and were vegetarian. Paranthropus robustus came from Australopithecus africanus. Perhaps, Australopithecus aethiopicus preceded it. Brain was 500 cc.
Paranthropus hominins {Australopithecus boisei} (Paranthropus boisei) were not on human line, were robust, weighed 50 kilograms, and lived in east Africa. Paranthropus had vegetarian diets, as shown by dentition and face. Brain was 500 cc to 530 cc.
Humans {Homo} {human} are vertebrates, mammals, and primates and share their fundamental behaviors.
evolution
Humans evolved from australopithecines. Strong sexual selection, complex social lives, changing environments, cultural effects, social contacts, increased population density, agriculture, food surpluses, and wars emphasize aggression, fitness, and intelligence. Humans evolved faster than apes. Humans evolved through pedomorphism, accounting for greater brain size, because children have relatively bigger brains.
evolution: environment
Early humans had direct competition with similar species and had predators.
development
Human life span is as expected for great apes with human size and brain.
behavior: hand
Hands have opposing thumbs and many available grips. Humans can gesture.
behavior: walking
Humans walk upright on strong legs. Upright walking requires mechanisms for balance, allows farther vision and greater lateral vision, requires learning gait, allows wider territory and means of sharing territory, and allows hand, foot, arm, and leg differentiation.
behavior: society
Humans live in organized groups. They have faces and know facial expression meaning. They perceive others' needs and desires. They know action effects on others. They react to others' behaviors and communications. They can have rapport. They can influence. They kiss.
behavior: language
Human language probably developed from graded primate vocalizations. Humans can pronounce 40 phonemes. They use voice modulation. They express feelings. Speech depends on upright posture, which allows tongue-position shifts and pharyngeal-tract lengthening. Humans use symbolic thought and language to plan and form strategies. Memories allow using and transmitting past knowledge. Humans have music.
senses
Humans use sight as dominant sense.
brain
In evolving to humans, supragranular layer became upper three cortical layers, middle layer thickened, subgranular layer divided into lower two layers, and secondary and tertiary sulci had increased associational areas.
handedness
Right-handedness first appeared in Lower Old Stone Age, when tool making became common. Starting 300,000 years ago, humans probably had cerebral dominance, because skulls are asymmetric and people inherit brain and skull shape. Human skulls mold to brains. Right-handers typically support and orient objects in left hand, without using visual feedback, and perform fine movements with right fingers, using visual feedback. Most people use right hand for gesticulation.
handedness: abilities
Performance by right-handers and left-handers is equal on all tasks. No special ability or disability distinguishes left-handers.
handedness: factors
Handedness inherits. Social pressures or early experience, especially with objects designed for right-handers, affects handedness. Brain damage before or after birth can shift cerebral dominance or prevent hemispheric specialization. Subnormal and epileptic people have more left-handedness.
handedness: anatomy
In right-handers, left cerebral hemisphere has sense and motor connections to both body sides, and right hemisphere connects to only one side. In left-handers, cerebral lateralization is less. In right-handers, left side has fewer skills, poorer timing and coordination, more variability, and more frequent and slower corrections.
handedness: ratio
Left-handers are 4% to 36% of people in different races and cultures.
handedness: mammals
Mammals besides humans show paw preferences but equally to left or right.
First humans {Homo habilis} split from Australopithecus.
size
Homo habilis was 1.35 to 1.5 meters tall and weighed 50 kilograms.
culture
Homo habilis formed Lower-Paleolithic Oldowan Culture. Perhaps, it had labor division, cooperation, and reciprocity.
culture: tools
Homo habilis chipped sharp flakes from larger stone cores. Perhaps, it carved wood tools.
digestion
Homo habilis ate plants and meat.
hunting
Perhaps, Homo habilis scavenged, hunted, and had food sharing.
body
Homo habilis had curved finger bones, long arms, short legs, and modified pelvic and leg bones.
walking
Upright walking on arched feet allowed better running, jumping, balance, and flexibility.
reproduction
No estrus in females allowed continuous sexual receptivity. Intervals between births are shorter for humans than for great apes.
skin
Few body hairs allowed skin sensitivity.
head
Homo habilis had post-orbital septum and thin brow ridges. Skull back was round.
brain
Large left-brain Broca's motor speech area indicates speech. Advanced vocal cords and brain language areas allowed better communication. Bigger frontal and parietal lobes were in 700-cc brains, with 4.0 encephalization quotient. Brain had sulci and gyrus patterns like Homo sapiens. Two more cell layers in neocortex increased processing complexity and information distribution.
senses
Homo habilis had reduced smell sense and integrated senses.
Early African Homo erectus hunter-gatherers {Homo ergaster} ate meat. Homo ergaster weighed three times more and was two times taller than Australopithecus. Homo ergaster came from Homo habilis.
Early Homo species {Homo erectus} was 1.65 meters tall.
evolution
Homo erectus came from Homo habilis and was ancestor of Homo floresiensis and archaic Homo sapiens.
anatomy: body
Homo erectus had narrow bowl-shaped pelvis and conical thorax. Homo sapiens has barrel shaped thorax.
anatomy: head
Homo erectus had heavy eyebrows, no chins, big jaws, and low skulls. Extra bone was on skull midline {sagittal keel}.
anatomy: senses
Homo erectus had sense organs like modern humans. Skull indents behind eyes, so eye sockets protrude.
anatomy: brain
Brains were 1000 cc, two-thirds of modern brains, with six-layer brain cortex, specialized right and left brain hemispheres, and association areas. Encephalization quotient was 5.5.
anatomy: teeth
Perhaps, Homo erectus gripped and tore using front teeth by prognathism.
anatomy: hand
Homo erectus held fingers to palm and had precision grips.
anatomy: arm
Homo erectus had large femoral heads like Homo sapiens.
anatomy: leg
Arched feet allowed better running and jumping, better balance, and more flexible movements. Arched feet had no grasping.
anatomy: sexual dimorphism
Male and female body sizes were more equal than in Homo habilis.
walking
Homo erectus walked fully erect.
reproduction
Homo erectus had sexual intercourse but no longer had estrus, so females were always sexually ready.
development
Babies were immature at birth, like Homo sapiens.
culture
Homo erectus had Acheulean culture of Lower Paleolithic. Groups with social organization lived in caves or later wood or bone houses and had territories. Homo erectus had birth rituals, long childhood with rites of passage to adulthood, and courtship rituals.
culture: communication
Homo erectus signaled and used simple speech. It planned for events far away in space and time. It realized world of individual things and people existed.
culture: fire
Starting 200,000 years ago, Homo erectus used fire for warming, lighting, scaring animals out of caves, hunting, hardening wood, cooking plants, cooking bones for marrow, and building community. It had specialized fire builders.
culture: tools
Homo erectus used flaked stone tools, chipped hand axes from large stone cores [-1500000], and had stone symmetrical hand axes with two sides [-750000]. Homo erectus carved wooden spears and wooden bowls.
culture: hunting
Homo erectus killed large animals, coordinated hunts, and gathered foods. Savanna had enough food to support two people per square mile. Hunting societies had one leader. Males were hunters and dominated life. Male friendship developed. Females did domestic work. Perhaps, aquatic societies lived on fish and shellfish, shared among all, had no leader, and lived near oceans or fresh water.
Homo erectus possibly used gripping and tearing by front teeth {prognathism}.
Archaic Homo sapiens {Homo heidelbergensis} came from Homo erectus. Homo heidelbergensis had larger brains, flatter faces, and smaller brow ridges. It invented prepared-core technique.
Neanderthals {Homo neanderthalensis} were strong.
evolution
Neanderthals came from archaic Homo sapiens [-700000 to -500000]. They became extinct [-35000]. They are not human ancestors, because Neanderthal mitochondrial DNA is not like Homo-sapiens mitochondrial DNA (Svante Pääbo), though genomes are 99.5 percent the same. Interbreeding among humans and Neanderthals stopped by 370,000 years ago.
posture
Neanderthals had same postures and body movements as Homo sapiens.
body
Neanderthals had barrel chests and short and large limb bones.
head
Neanderthals had reduced skull thickness, low skulls, no chins, broad noses, heavy jaws, low and sloped foreheads, and heavy arched brow ridges.
teeth
Neanderthals had human teeth, which they used as clamps or vises.
handedness
Neanderthals had handedness.
brain
Brain was 900 cc to 1100 cc, with expanded parietal lobes. Special brain language areas were on left side, with right-left brain asymmetry.
language
Neanderthals spoke. Perhaps, Neanderthal throat anatomy inhibited good speech.
walking
Neanderthals walked erect.
habitat
Neanderthals lived in caves in cold climates.
culture
Neanderthals had Upper or Late Acheulian Culture of Lower Paleolithic and Mousterian Culture of Middle Paleolithic. They had customs and laws for societies.
culture: hunting
Neanderthals were big-game hunters, used wood spears with fire-hardened points [-50000], used flint weapons, and wore animal skins.
culture: fire
Neanderthals used fire [-500000] in Zhoukoudian cave in north China and had hearths.
culture: burial
Neanderthals buried the dead [-100000].
culture: painting
Neanderthals gathered red ocher.
Advanced humans {Homo sapiens} probably began in Africa 100,000 to 200,000 years ago. African and non-African Homo sapiens then diverged.
habitat
Early Homo sapiens lived in caves.
brain
Early Homo sapiens had brains the same size as now, with 7.6 encephalization quotient. It had new associational-cortex and frontal-lobe development. It had consciousness.
culture: tools
Early Homo sapiens used chipped stone tools and built tools to make tools.
culture: language
Early Homo sapiens probably spoke and knew symbols and language.
culture: clothing
Early Homo sapiens wore clothing.
culture: fire
Homo sapiens used sustained fire [-40000].
culture: domestication
Homo sapiens domesticated plants and animals [-8000]. Homo sapiens used medicinal herbs in Iraq [-8000].
Growth {development} begins at fertilization, continues through embryo and fetus, and includes birth, infant, toddler, child, adolescent, and adult stages.
All body parts can be for, and form by, one organism, and one organism can be for, and form by, all parts {autopoiesis}. Organisms can generate themselves.
Genes can have different effects if they are from mothers or fathers {imprinting, development}|. Imprinting affects at least 75 human genes with imprinting centers, such as genes that make placenta and head. Mouse Nest gene is on X chromosome and causes maternal behavior: nest-building, retrieving babies, and cleaning babies. Imprinting silences mother's Nest gene. Father's Nest gene expresses.
cause
Fertilized egg cells need one male and one female pro-nucleus. Eggs with two male, or two female, pro-nuclei cannot live. CG-site methylation inactivates mother or father genes at imprinting centers. Imprinting ceases several days after conception, then sometimes recurs, and then finishes halfway through gestation.
gene types
Perhaps, father-imprinted genes make muscles, hypothalamus, amygdala, and preoptic region, and mother-imprinted genes make forebrain, cortex, striatum, and hippocampus.
In development, environmental aspects {nurture, development} have equal importance with genes {nature, development} [Carey, 1987] [Winick, 1978].
Animals have two or three embryonic-cell types {germ layer}|: endoderm, mesoderm, and ectoderm. Germ layers develop from coelom tubes.
Outer tube {ectoderm}| becomes senses, nerves, and outer skin.
Cells between ectoderm and endoderm {mesoderm}| become muscles and glands in three-germ-layer animals. Two-germ-layer animals have no mesoderm.
Inner tube {endoderm}| becomes digestive tract.
Brain and nerves develop structures and functions {brain, development} {nervous system, development}. Neurons move by amoeboid motion to final locations, guided by glia. At final locations, special molecules bind neurons together in layers or masses. Neurons send out dendrites and axons, which grow toward targets marked by chemicals, mostly to same-type neurons. Brain makes more dendrites and axons than it can use, so it eliminates many after growth finishes.
multisensory to unimodal development
During maturation, brain transforms multisensory regions to unimodal regions.
topological maps
During development, brain coordinates sense-organ movements and perceptions using attention mechanisms, to align sensory maps in superior colliculus and to maximize sensitivity.
consciousness
During human development, consciousness increases gradually as brain develops structures and functions [Aoki and Siekevitz, 1988] [Borrell and Callaway, 2002] [Carey, 1987] [Schaeffer-Simmern, 1948]. Embryos before three weeks old are unlikely to have sensations, because neurons are just forming. Children older than three can remember sensations.
Head evolved {cephalization} to hold sensors and integrate sense and muscle ganglia.
During development, invertebrates can change actions to opposite actions {reactive inhibition}.
Children develop ideas about their and other minds {theory of mind, development}. Knowing what relation moving or stationary objects have to oneself {intentionality, mind} begins at nine months old. Following another's eye direction toward distant objects begins at nine months old. At age 12 to 24 months, infants realize that people are pointing at or looking at something. Knowing that another person is looking at same object {attention sharing}, so two people attend to same thing, begins at 18 months old.
At age 24 to 36 months, toddlers start talking about goals, feelings, and thoughts. Later, they learn that perceptions from their viewpoint differ from perceptions from other viewpoints. Later, they learn that beliefs can be false and that people can deceive.
By four years old, children know that they and other people have beliefs and goals and that these guide behavior {belief-desire reasoning}.
autism
Autistic children appear to have no theory of mind.
animals
Animals seem to have no theory of mind.
test
False-belief tests can check if people have theories of mind. People can see someone place something at a location and see someone else move it while the first one is not looking. Tests ask people to name place where the first one will look for something.
People with theories of mind realize that the first one does not know that something moved, so the first one will look at the original place. People with no theory of mind will think only that something is now in new position and that everyone knows where it is, so the first one will look in the new place. If people do not know where the first one will look, they are still developing theories of mind.
From neural tube, glial processes extend into outlying regions {glial trail}. Developing neurons move along glial trails to final locations. Neurons that develop near each other in neural tube are near each other in outlying regions.
Axon tips {growth cone} have filopodia that guide axons to correct regions and synapses. Proteoglycans cover dendrites and cell bodies afterward. chABC enzyme cuts proteoglycans and allows more axon connections.
Axon-tip growth cones have cilia-like projections {filopodia} that guide axons to correct regions and synapses.
Development involves cell specialization {differentiation, cell}.
Maturational processes {induction, cell} make cells differentiate and control cell specialization.
During development, structural, functional, and behavioral changes {maturation}| can be due only to physiological growth. Maturational processes include cell induction.
directions
Muscle maturation and control start close to trunk and progress toward limbs. Maturation goes from head to tail {cephalocaudal sequence, maturation}.
enrichment
Enriched environments featuring interactions, not just passive stimulation, can transiently raise brain protein, RNA, and hexokinase levels but not gene-expression amounts. Enriched environments can increase dendritic branching and synapse number but not cell volume [Carey, 1987] [Shatz, 1992].
Cell division and specialization determine later cells and tissues {fate mapping}.
Nucleoproteins {organizer} can determine embryonic regions.
Maturation and muscle control begin at head and progress toward tail {cephalocaudal sequence, development}.
Maturation increases movement precision {mass action to differentiation sequence}.
Proteins {morphogen, protein} can set up concentration gradients across embryos.
Embryos have development stages that correspond to phylogenetic-evolution stages {recapitulation, development} {ontogeny recapitulates phylogeny}. First embryo stage corresponds to simple and ancient ancestor. Following embryo stages are later and more-complex ancestors. Last stage is current species.
Individual development {ontogeny}| continues from conception to death and includes structure, function, and behavior changes. Genes and development processes determine growth, form, and behavior.
Species begin with simple and ancient ancestor species and evolve to become more-complex species {phylogeny}|.
Embryonic development follows taxonomy and reflects organism evolution recorded in fossils {threefold parallelism}>: development, taxonomy, and fossil record.
Development makes body structures by cell division {morphogenesis}|. Cell differentiation decreases cell adhesion, increases cell deformability, and increases cell motility. Morphogenesis increases serine proteinase, cysteine proteinase, aspartic proteinase, and metalloproteinase. Cell receptors for regulated trophoblast implantation, mammary gland involution, embryonic morphogenesis, and tissue remodeling alter.
Development makes body structures by cell specialization {epigenesis}|.
Development stages {development stages} are gestation of embryo and fetus, birth, infant, toddler, child, adolescent, and adult.
Pregnancy {gestation}| has embryonic and fetal stages. Human embryonic and fetal development takes 280 days or 40 weeks [Winick, 1978].
cells
Approximately 50 cell divisions happen from zygote to newborn, making 256 or so cell types and 10^15 cells.
DNA
DNA one-dimensional molecules can encode embryo development in three spatial dimensions and one time dimension, because embryonic development uses relative times and positions.
development genes
Development genes have many and long introns and many regulatory regions. Development genes express in same order as order on chromosome, which is also spatial order of organism tissues and organs. Development genes turn on and off in cascades. Successive stages depend on previous stages. Transcription factors and receptors cause different gene-regulation and gene-expression patterns and so different cell types.
fertilization
At fertilization, maternal-effect genes code transcription factors that establish top-to-bottom embryo polarity. Bicoid morphogen, at one pole, sets up top-to-bottom gradient. Follicle-cell maternal-effect genes code transcription factors that establish front-to-back embryo polarity. Nanos morphogen, at other pole, sets up gradient across embryo.
Dorsal protein transcription factor, similar to rel protein and NF-kappaB, concentrates in cell nucleus ventrally, and cytoplasm dorsally, in all embryo cells. Cactus and Toll genes can partition dorsal protein to cell locations. Perhaps, Toll proteins are receptors.
gap genes
After first cell divisions, gap genes code transcription factors, with zinc fingers, that make bands along embryo by working with maternal-effect genes and by repressing each other. Gap genes are hunchback, Kruppel, knirps, and hunchback-maternal. Gap genes also regulate genes expressed later. Transcription-factor binding sites are high-affinity or low-affinity, so transcription-factor concentration affects which genes transcribe and how much, leading to gradients and bands.
segmentation genes
After gap-gene expression, segmentation genes code transcription factors that make number of segments, pair segments, and give polarity to segments. Segmentation genes work with gap-gene products and interact with each other, using autofeedback, to sharpen segment boundaries. Segmentation genes include pair-rule genes, such as fushi tarazu gene, even-skipped gene, hairy gene, runt gene, and eve gene.
homeotic genes
After segmentation-gene expression, homeotic genes, such as vertebrate HOX genes, code transcription factors that determine body-part type, such as antenna or thorax. Homeotic genes work with pair-rule pairs to make segments differentiate. All homeotic genes evolved from one gene by gene duplication. Homeotic genes have homeoboxes, which make homeodomains, which bind to DNA promoter sequences to control transcription. All animals have homeotic genes.
torso and polehole genes
After segmentation-gene expression, head and tail develop. For transcription factors only in head and tail, torso gene makes protein-tyrosine-kinase membrane receptors. Polehole gene, similar to raf proto-oncogene, makes protein-serine, threonine kinase that acts on head and tail growth-factor receptors.
proneural genes
After head and tail develop, proneural genes, such as daughterless and achaete-scute, code for transcription factors, with helix-loop-helix, that make neural precursor cells to start brain development. da enhances achaete-scute. enc inhibits achaete-scute.
neurogenic genes
Then neurogenic genes, such as notch, split enhancer, big brain, mastermind, and neuralized, make cell-to-cell signal proteins for cell adhesion, signal transduction, membrane channels, and transcription factors. Neurogenic genes develop cells and inhibit nearby cells.
selector genes
Then selector genes, such as cut gene, code for homeobox transcription factors that make neuron types.
neurotrophic genes
After neurons creation, neurotrophic genes code for secreted neurotrophic factors that keep neurons alive, differentiate neurons, and make neurotransmitters, such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), CNTF, and NT-3. Other genes code neurotrophic-factor receptor proteins.
information from mother
Fetus can use information about mother and environment, such as orientation information. Fetus needs to know relation to mother to aid survival.
1 day: Cell division makes egg cell into a many-celled ball {blastomere}, with same volume and mass as egg cell.
1 day: Cell division {cell cleavage} makes egg cell into blastomere.
4 days: Human embryos {morula} have 10 to 30 cells.
5 days: Human embryos have several hundred cells in one layer in a hollow sphere {blastocoel} {blastocyst}, with inside cavity filled with fluid. Human blastocyst has extra cells at one spot.
5 days: Lower-animal embryos have cell spheres {blastula}.
1 week: Embryos several days old have stem cells {embryonic stem cell, gestation}| (ES cell). Embryonic stem cells can uptake and insert genes by homologous recombination. Adding altered stem cells can change mice embryos. Mouse blastocysts have inner cell layer, which can culture with fibroblasts or with leukemia inhibiting factor to prevent further differentiation.
1 week: Cells that will make brain and spinal cord first roll into a hollow cylinder {periventricular germ layer}, then multiply around that cavity, and then migrate outwards to form neuroblasts.
1 week: Cells that will make brain and spinal cord first roll into periventricular germ layer, then multiply around that cavity, and then migrate outwards to form brain nuclei {neuroblast}. Later cells pass through earlier cells, so younger cells are on outside.
1 to 3 weeks: Neuroblasts make cell slab {cortical plate} in embryo upper layer. Two hemispheres form around ventricles.
10 days: Two fluid cavities, yolk sac and amnion sac, develop inside cell sphere {chorion} {gastrula}.
10 days: Two fluid cavities develop inside gastrula. Fluid cavities {amnion sac}| can have ectoderm inside.
10 days: Two fluid cavities develop inside gastrula. Fluid cavities {yolk sac}| can have endoderm inside, to later make primitive gut.
10 days: Yolk sac has endoderm {primitive gut} inside.
10 days: In hard-shell eggs, one cavity {subgerminal space} is away from yolk, under dividing cells.
14 days: Embryo has 800 cells. Ectoderm disk lies under endoderm. Mesoderm grows between endoderm and ectoderm and splits into two sheets, one on ectoderm and one on endoderm, with a fluid cavity {coelom, development}| between sheets.
14 days: Endoderm disk has line {primitive streak}| of cells along longitudinal body-axis top. At anterior end, primitive streak becomes more specialized and has no segments, like notochord.
2 to 3 weeks: Ectoderm above notochord makes first neural plate, then neural groove, then neural folds, and then neural tube {neural tube}|.
2 to 3 weeks: Neural tube has inner ventricular zone {ependyma} around central ventricle, intermediate-zone or mantle-layer gray matter, and marginal-zone or pia white matter. Ependyma becomes CNS neurons and glia.
2 to 3 weeks: Neural-tube mantle layer becomes dorsal sense neurons {alar plate} and ventral-motor-neuron basal plate.
2 to 3 weeks: Neural-tube mantle layer becomes dorsal-sense-neuron alar plate and ventral motor neurons {basal plate}.
2 to 3 weeks: Mesoderm {neural crest}| lies next to neural tube and makes adrenal medulla, sympathetic ganglia, and dorsal-root ganglia.
2 to 9 weeks: Embryo {embryo, animal}| grows first at head and then down sides. First, disk sides curve up and around notochord at head. Then disk sides curve down to tail. Body folding makes digestive-system foregut and hindgut.
2 to 9 weeks: In vertebrates, embryos are cylindrical bodies {neurula}, with ectoderm layer on outside reaching over notochord, mesoderm layer, and inner endoderm tube.
2 to 9 weeks: Ventral-body-wall constriction makes a tube {umbilical cord}| {umbilicus} come out from belly. Tube has outer ectoderm, middle mesoderm, and inner endoderm.
15 days: Egg yolk {yolk, egg}| can be throughout cell {isolecithal}, at one end {telolecithal} or in center {centrolecithal}. Mammalian eggs have little yolk.
3 weeks: Brain interneurons send axons down brainstem to spinal cord and up to forebrain {interneuron development}. Axons transmit messenger chemicals to other neurons to integrate central nervous system. Medulla oblongata appears at neural-tube first flexure. Soon after, diencephalon appears at second flexure. Last neuroblast cells, having left-right asymmetry, migrate.
4 weeks: Forebrain telencephalon and diencephalon, midbrain, and hindbrain pons and medulla differentiate {brain divisions}.
4 weeks: Embryo floats in amniotic sac, connected to uterus wall only by umbilical cord. Embryo has large head, gills, tail, somites on notochord sides, and beating heart {head and heart development}.
4 weeks: Guided by chemical or electrical signals with no learning, brainstem and spinal-cord ventral motor cells grow axons to trunk, limb, and viscera muscles {motor cell and movement}. Fetal birds and mammals have varied movements, even before sense nerves appear.
4 weeks: Embryo has mesoderm muscle precursors {somite}| on notochord sides.
4.5 weeks: Spinal ganglia begin forming {spinal ganglia development}. Pons and cerebellum appear at neural-tube third flexure.
5 weeks: Sensory nerve tracts begin {sense-nerve development}. Epithelial sensory cells project to brainstem and spinal-cord dorsal half, which also receive from head sensory receptors. Old cortex, cerebral medulla, and basal ganglia appear at neural-tube fourth flexure.
6 weeks: Arms and legs appear, reflex-arc elements appear, sympathetic ganglia form segmental masses, hypothalamus and epithalamus begin, and cerebral hemispheres start {hypothalamus development}. Embryo is 12 millimeters long.
7 weeks: Thalamus, corpus striatum, and hippocampus begin {thalamus development}. Y-chromosome stimulates cell division and causes embryonic gonad medulla to differentiate into testis.
7.5 weeks: Spinal reflexes work, and limbic lobe begins {limbic lobe development}.
8 weeks: Embryo is 25 millimeters {cerebral cortex development}. Face has eyes, ears, and nose. Arms and legs have fingers and toes. Embryo has small tail and all internal organs. Brainstem has many projections into cerebral cortex to guide cortical-neuron migration and differentiation. Eight weeks ends embryonic period and begins fetal period.
9 weeks: Anterior commissure appears {anterior commissure development}. Testis secretes androgenic hormones to organize genitalia and brain. Fetus has red, wrinkled skin.
9.5 weeks: Hippocampal commissure appears {hippocampal commissure development}.
10 to 23 weeks: Corpus callosum appears {corpus callosum development}, but, in the next three months, it trims most callosal axons.
10.5 weeks: Spinal cord has internal structure {spinal cord development}. Fetus has localized movements. Neocortex parietal lobe starts.
10.5 weeks: Baby teeth {deciduous teeth}| appear.
12 weeks: Sex differences are present {brain layer development}. Fetus is 75 millimeters. Deepest cortical layers five and six appear.
12.5 weeks: Spinal cord has reached next organization stage {brain connection development}. Connections from neocortex to hippocampus start.
14 weeks: Long sensory tracts appear in spinal cord, and flocculonodular lobe appears {sensory tract development}.
15 to 25 weeks: First neocortical cells are around cerebral-hemisphere cavities and move into cortex {neocortex development}.
16 weeks: Spinal-cord ventral-root myelination begins {myelination development}, old cerebellar vermis is in position, corpora quadrigemina appear, neocortex has first layering stage, and parietal and frontal lobes separate.
18 weeks: Occipital lobe and temporal lobe separate {brain lobe development}.
19.5 weeks: Tract myelination from spinal cord to cerebellum and pons begins, and dorsal-root myelination begins {tract myelination development}.
20 weeks: Pyramidal tracts from cortex begin {pyramidal tract development}. Fetuses have REM sleep, indicating dreaming. Inner neocortex layers mature. Fetuses can have voluntary movements. Fetuses can move eyes, which aids eye development. Hair appears. Fetus is 250 millimeters. Malnutrition, narcotics, and emotional stress raise blood epinephrine level and cause hyperactivity.
22 weeks: Outer neocortical layers mature {outer neocortex development}. Bone ossification and teeth calcification begin.
24 weeks: Some left-temporal-lobe and parietal-lobe regions become asymmetric {brain asymmetry development}. Ventral commissure myelinates. Cranial nerves myelinate through midbrain. All cerebral-hemisphere commissures are complete. Brain has all cortical layers.
26 weeks: Brain areas that will attain mature tissue structure only at adolescence are the last to receive neurons {brain final development}.
28 weeks: Tract from spinal cord to thalamus myelinates through midbrain {brain convolution development}. Tract from spinal cord to cerebellar vermis myelinates. Cerebellum configuration is in place. Cerebral convolutions and fissures start.
32 weeks: Secondary and tertiary sulci start {brain sulci development}.
32 to 40 weeks: Brain weight increases four times during last two gestation months {brain weight development}. It continues to increase during first infancy months, while making more axons, dendrites, and synapses. After that, neuron number is constant. In fetus, sorting, editing, and removing sense and motor connections depends on maternal-environment external-stimuli timing and spatial arrangement.
40 to 41 weeks: Size at birth relates to maternal size, so large women have large babies {birth, development}.
newborn {neonate}| {newborn} {neonatal}.
Newborns can follow slowly moving lights, react to brightness changes, turn in touched-cheek direction, cry, thrash, yell, cough, vomit, turn away from stimuli, lift chin while lying on stomach, smack lips, chew on fingers, flex limbs, extend limbs, react to loud sounds, creep, shiver, jerk, arch back, draw in stomach, and twist {behavior, newborn}. If spoken to, newborns can smile, coo, and make hand gestures. Newborns can find breast in few feedings. At feeding, mothers speak to and smile at newborn girls more than boys.
Almost all central-nervous-system neurons are present at birth {brain development, newborn}. Most brain connections are present at birth in humans. Brainstem, thalamus, amygdala, and deep cerebellum are active. Dendrites are growing, and synapse number is increasing.
cells
After birth, only some neurons can divide and reproduce. During maturation, 80% of neurons die.
learning
Brain growth before birth and during infancy aids learning, and learning aids growth, because both use self-organizing processes.
hormone
In fetus and infancy, sex hormones influence visual cortical areas.
All senses are present {cognition development, newborn}.
sound
If newborns are alert, high sound frequencies cause freezing, but low ones soothe crying and increase motor activity. Rhythmic sounds quiet newborns. Newborns can make vowel sounds and several consonants. In first few days, newborns can discriminate among different speech syllables and emotional tones. Newborns prefer to hear mother's voice.
smell
In first few days, newborns can distinguish people by odor.
vision
Newborns learn mother's face in two or three days. Newborns can detect patterns in recurring events and objects and make rules about perceptual distinctions. Gaze focuses only at 20 centimeters away. Newborns have wide-open eyes that can move stepwise to fixate on bright places or to track stimuli in motion. Newborns turn toward faces that approach closely and speak gently.
cognition
Newborns can record recent-event times and locations. Neonates are conscious and have emotions. Newborns can learn but need longer times for memory consolidation. Newborns express puzzlement, surprise, pleasure, and displeasure. Newborns can try to avoid experiences.
Newborns have random bowel movements {defecation development}. Urination is often but tiny.
Newborns can eat seven to eight times a day {eating development}.
00 to 01 week: Newborn males are 50 centimeters and 3.5 kilograms {first stage of development}. Fat is under skin. Girls have less muscle mass, greater fat proportion, smaller water proportion, faster development rate, and smaller variation. At birth, males are heavier and longer than females. Males are more susceptible to postnatal and perinatal complications. By bone age, newborn girls are like five-week-old boys.
00 to 01 week: Skull has six soft spots {fontanelle}|, which harden to bone by two years old.
Reflexes include ankle clonus, arm reflex, Babiniski reflex, eye reflex, eyelid closing reflex, inner thigh reflex, jaw-jerk, Moro reflex, necking reflex, pupillary reflex, reach-and-grasp reflex, rooting response, newborn traction, voice reflex, and withdrawal reflex {reflex, newborn}.
Newborns sleep 80% of time, with seven to eight short naps per day {sleep, development}.
0 to 1 month: Inadequate eye accommodation and convergence cause infants not to attend to objects within arm reach {cognition development, 0 to 1 month}. During first month, infants can pursue objects with eyes and head. Babies less than a month old can imitate facial expressions. Over first weeks, infants learn to recognize individuals by voice. According to Piaget, infants have reflex schemas, such as sucking and grasping.
0 to 4 months: Infants less than 16 weeks old look at positions, not at objects {vision development, 0 to 4 months}. They do not know size, shape, or color. They can follow movements. They believe that moving objects differ from stationary objects. They believe that objects are solid and permanent.
Breastfeeding {breastfeeding}| {nursing, development} provides nutrients and antibodies but often stops at five months in USA.
In first months, parents tend to handle boys more than girls {handling, development}.
Mutual trust develops between baby and mother {bonding, development}|. Conflicts also happen as baby explores forbidden objects in wrong places or ways, or wants to do one thing while mother wants to do another. Such conflicts start when infants can reach and grasp objects. Such conflicts lead to playfulness, teasing, testing, sharing, games, and understanding. Baby knows mother's attention and emotions through interactions. Infant games have easy patterns in time and space and contribute to curiosity and companionship.
Infants and children are always testing to improve perceptions and reactions {cognition development, 0 to 12 month}. Infants never confuse themselves with objects outside themselves. Infants recognize that other people have motivations and emotions. Traditional nursery songs, chants, and rhymes are in all cultures, so babies know musical communications before they can speak. Baby soon knows mother and father as particular individuals. Infants are most interested in events caused by human movements.
Babies stimulate gentle and questioning talk, which has regular beats and gentle moods. Baby talk has changing intonation and rhythm and has head, eyebrow, and eye movements. Infants watch intently, reply {pre-speech} on beat, smile, and move head and body. Baby pre-speech is developmentally necessary to actual speech.
Infant boys have spontaneous penile erections {sex development, infant}. Infant girls can have spontaneous vaginal lubrication.
0 to 4 years: Children grow rapidly, but growth rate slows from 20 centimeters per year to 6 centimeters per year {physical development, 0 to 4 years}. From age 2, child height relates to average parent height, with equal influence from both. Nutrition is greatest environmental influence on growth. Severe psychological stress can affect growth. Fastest growth is in spring.
0.5 to 2 months: Infants stick up chins, take two to four naps a day, empty bowels three to four times a day usually when awake, eat one liter a day, and coo using tongue {second stage of development}.
1 month: Infants eat five to six times per day, 600 milliliters total {physical development, 1 month}.
1 month: Infants can establish eye contact {vision development, 1 month}. Infants can have gaze aversion.
1 to 4 months: According to Piaget, infants adjust schemas after encountering new stimuli {accommodation, schema}. Infants do not think about their effect on environment yet.
1 to 4 months: According to Piaget, infants join hearing, looking, and smiling to previous schemas {assimilation to schema}.
1 to 4 months: According to Piaget, infants have repeated hearing, looking, and smiling {primary circular reaction}.
1 to 6 months: Infants have two emotions: undifferentiated excitement associated with tension or need and undifferentiated relaxed quiescence {emotion development, 1 to 6 months}. Fear is undifferentiated reaction to strange, unexpected, or dangerous stimuli.
From one to six months after birth, idealized human faces and/or voices cause smiles {smiling response development}.
From 1 to 12 months, babies fear noises, falling, fast movements, light flashes, strange objects, and people and animals associated with pain {emotion development, 1 to 12 months}.
1.5 months: Babies notice objects {cognition development, 1.5 months}.
1.5 months: Reflexes open and close eyes, change pupil size, cry, suck, yawn, frown, sneeze, swallow, vomit, close hand, turn head, arch back, and vocalize {reflex development, 1.5 months}.
1.7 months: Babies can smile {cognition development, 1.7 months}.
2 months: Pyramidal tracts myelinate through medulla oblongata, fibers from spinal cord to cerebellum myelinate, and optic tracts myelinate {brain development, 2 months}.
2 months: Babies can imitate vocalizations, hand opening, and soft clapping {cognition development, 2 months}. Probably perception and motor behavior are together. Imitation behavior involves both imitator and imitated equally. Babies babble when talked to. Legs start growing fast. Visual attention is greatly increased.
2 months: Boy calorie intake is greater {physical development, 2 months}.
2 months: Eye and head movements can predict moving-object future positions, but arm movements do not relate to vision {vision development, 2 months}.
2 to 3 months: Eye accommodation begins. Infants can put chest up. Bowels empty twice a day, usually when waking or eating. Infants can eat solid foods {third stage of development}. Environments affect babbling.
2 to 3 months: Infants visually attend to nearby objects and take visual interest in their arms {vision development, 2 to 3 months}. First visually directed arm-swiping movements develop, but infants grasp objects only if hand touches them.
2 to 6 months: Axon-collateral dendrites branch greatly {brain development, 2 to 6 months}. Most synapses develop several months after birth.
2.5 months: Baby eats three to four times a day, one liter a day {physical development, 2.5 months}.
3 months: Babies have directed arm movements and look back and forth between objects and hands {behavior, infant}. Babies can reach to touch but miss. Babies put objects or hands in mouth. Babies can laugh. Same-stimulus repetition is boring. Babies can sit with support.
3 months: Cortex begins to function, convolutions begin, conscious motor acts begin, and brain controls primitive reflexes {brain development, 3 months}. Cells in cortical layers five and six are functioning but not other cortical cells. Intraorganismic short circuit is present and stable. Parietal lobes are active.
3 to 4 months: Babies can know depth, orientation, size constancy, shape constancy, completion, motion parallax, and binocular parallax {cognition development, 3 to 4 months}. Using three dimensions and depth uses convergence and eye coordination. Babies recognize people as strangers. Infants watch their two hands as they contact and manipulate each other. Infants can distinguish human faces. Infants make sounds in response to internal states.
4 months: Redundant axons are gone, and synaptic fields are complete {brain development, 4 months}. Interhemispheric fibers receive myelin sheaths.
4 months: Laughter first appears {cognition development, 4 months}. It requires safe or playful moods and unexpected situations.
4 months: Grasp reflex ends {reflex development, 4 months}. Infants can have bowel movements at eating time.
4 to 7 months: Eye accommodation is same as for adults, meaning plays role in perception, and babies can eat cereals and vegetables {fourth stage of development}.
4 to 8 months: According to Piaget, infants react to stimuli {secondary circular reaction}, so action repeats. Infants treat objects out of sight as if they are not there.
Five-month-olds seemed surprised that drawbridges can go through boxes {drawbridge study}.
5 months: Babies can use both arms together under visual control and can reach rapidly to grasp objects {physical development, 5 months}. Babies play with toes.
5 months: Reach and touch reflex ends {reflex development, 5 months}.
6 months: Neocortex layers one, two, and three myelinate {brain development, 6 months}. Babies can make all language sounds. Eye acuity is the same as for adults. Frontal lobes become active. Theta waves appear.
6 to 12 months: Babies have strong affection for mother and are afraid of, or distressed by, strangers {cognition development, 6 to 12 months}.
7 months: Delta and alpha waves appear {brain development, 7 months}.
7 months: Babies can sit up without help {physical development, 7 months}. Babies can roll.
7 to 12 months: First tooth appears. Babies express anxiety at surprise, can sit with no support, and can sleep through night with two or three day naps {fifth stage of development}. Babies probably do not dream. Urination can cease for one to two hours.
07 to 24 months: Infants can have acquired fear of separation from mother {emotion development, 7 to 24 months}.
7.5 months: Brain-wave pattern is continuously present {brain development, 7.5 months}.
8 months: Babies can crawl {physical development, 8 months}.
8 to 12 months: According to Piaget, infants coordinate secondary schemas by goal-directed activities, problem solving, and associating actions to future actions {cognition development, 8 to 12 months}. Infants treat hidden objects as if they are still there.
9 months: Layer 3c and layer 4 cortical neurons are functional {brain development, 9 months}. Sensory tracts between thalamus and primary sensorimotor cortex are ready. Motor tracts between motor cortex and cerebellum are ready. Thalamus and lower gyrus-cinguli layers are in intraorganismic short circuit. Brain-wave waking and sleeping patterns are like adult.
9 months: Infants know other's wishes or intentions in shared things, and mother's purposes and experiences become primary {cognition development, 9 months}.
9 months: Forefinger grasping ends {reflex development, 9 months}.
9 to 12 months: Reaching-behavior control allows infants to reach anywhere, not just along sightlines {physical development, 9 to 12 months}.
10 months: Babies can creep {physical development, 10 months}. Babies can walk with help.
Babies produce all speech sounds {babbling}|. Babies can make 90 different language sounds.
12 months: Pyramidal tract has myelin {brain development, 12 months}.
12 months: Attachment to people develops attention and representation {cognition development, 12 months}. One-year-old infants play reciprocal or cooperative games, typically with parents, involving companionship, shared experiences, and symbol use. Babies like familiar playmates. One-year-old infants have short-term memory. Infants are aware that objects are there, though they do not see them.
12 months: Infants want to please parents {emotion development, 12 months}. Infants want to satisfy their wills right away. Conditioned fear reactions correlate with pain.
12 months: Infants can communicate needs, feelings, and motives to other people {language development, 1 year}. Infants make sounds about their experiences, addressed as comments or queries to others for affirmation or complements. Infants create baby words to specify objects to others. Infants understand household-object names. First-year infants imitate sounds, discriminate phonological distinctive features, and develop phoneme boundaries.
12 months: Babies can reach accurately for objects using hands and fingers {physical development, 12 months}. Babies have six teeth. Males are 70 centimeters long and 9.5 kilograms.
12 to 18 months: Toddlers can creep using feet, pull themselves up, and grasp like adults. Toddlers sleep 50% of time, urinate every four hours, eat three times a day, like some foods, and do not like wet diapers {sixth stage of development}.
12 to 18 months: According to Piaget, children actively experiment with environments, using curiosity, trial, error, and close observation {tertiary circular reaction}. Children know object spatial positions.
12 to 24 months: Infants use nouns as substitutes {overextension} for categories, features, or functions {chain complex nucleus} {prototype, noun}. Children do not overextend nouns that they hear.
12 to 24 months: Infants can direct angry expressions, such as having tantrums, kicking, thrashing, screaming, and holding breath, at things or people {emotion development, 12 to 24 months}. Children learn to use aggression. Children fear noises, strange events, falling, dark, being alone, and people and animals associated with pain.
12 to 24 months: Children associate words with sounds, based on context {language development, 12 to 24 months}. Familiar-object or people names are earliest words, but children also learn words expressing feelings and needs, so all word classes are present. For young children, words share features and functions. Word classes used by children do not correspond to classes used by adults.
12.5 months: Children can imitate words {language development, 12.5 months}.
13 months: Children can throw balls {physical development, 13 months}.
14 months: Children can walk sideways and put one cube on another {physical development, 14 months}. Children can stand without help and climb stairs. Attention level increases. First meaningful speech begins.
14.5 months: Children can walk backwards {physical development, 14.5 months}.
15 months: Neocortical layer five and six axons extend tangentially into layer one {brain development, 15 months}.
15 months: Children make two-word phrases {language development, 15 months}.
15 months: Children can walk without help {physical development, 15 months}.
17 months: Children can use stick to get toys {cognition development, 17 months}.
Language areas activate {brain development, 18 months}. Pre-frontal lobes activate, along with self-consciousness.
First life stage {infancy} ends at 18 months.
18 months: Children can say 4 to 50 words, with average of 22 words {language development, 18 months}. Children make two-word phrases. Children have no frustration if not understood.
18 months: First, words stand for whole sentences {syncretic meaning}.
At age 18 months, pre-frontal lobes and language areas become active, and self-consciousness begins {self-consciousness, development}.
18 to 24 months: According to Piaget, children use conceptual and symbolic thought for planning and foresight, imitate after delay, play, use combinations, and have imaginary objects {cognition development, 18 to 24 months}.
19 months: Children can put shapes into boards {cognition development, 19 months}.
19 months: Speech using words that refer to oneself, like "I", "my", "mine", "me", and "myself", or names with verbs, begins at 19 months and is common by 27 months {language development, 19 months}.
19.5 months: Children can follow directions for pointing {cognition development, 19.5 months}.
23.5 months: Children can mend simple breaks in dolls {cognition development, 23.5 months}.
2 years: Fissures between brain lobes are present {brain development, 2 years}. Children have 75% of adult brain. Cerebellum is 80% of adult weight. Vertical exogenous fibers connect cortex with subcortex. Subcortical association fibers, layer-one tangential fibers, and horizontal exogenous fibers develop. Cortex layer 3b is functional and has thalamus and association-area tracts. Association-area outer sections are functional. Cortex motor tracts modify sense pathways.
2 years: Children do not know that minds have beliefs, hopes, and desires {cognition development, 2 years}. Children like to imitate, like to identify, can build towers of 6 to 7 blocks, can repeat two digits, can name doll body parts, and can tell objects by use. Young children first draw heads and then draw legs and arms. Two-year-old children attach arms to largest previous shape. When drawing, young children try to organize all lines into patterns, rather than copying real world.
24 months: Children like to have mother present {emotion development, 24 months}. Personality begins.
24 months: Children acquire grammar {language development, 24 months}. First, children combine verb and noun or adjective. Two-year-olds do not realize that they have thoughts or that speech has words. Vocabulary is 6 to 126 words.
24 months: Children average 0.8 meters and 12.5 kilograms {physical development, 24 months}. Handedness begins.
2 to 3 years: Children identify with parents, usually same-sex parents, and usually have several more role models {emotion development, 2 to 3 years}.
identification
Identification depends on perceived similarities between child and adult. Identification is unconscious and does not involve imitation. Identification is stable. Identification has motives, traits, and behaviors. Identification results in sex typing, conscience, and guilt.
dependence
Children are highly dependent on adults. Children cling, touch, cry, and seek affection {separation anxiety}. Children use aggression, including whining, sulking, and peevishness. Children begin to use defense mechanisms, such as withdrawal, regression, denial, repression, and projection.
2 to 3 years: Children learn tense, number, and other word-association rules and build simple sentences from words {language development, 2 to 3 years}. Two-word sentences, like action-object and actor-action, use main word in one position and another general word to add meaning. Children express locations or desires, not what they think. Children can comment on topics if they can use predicates. Children cannot understand or use metaphors.
2 to 4 years: Abdomen is large, protruding, and round {physical development, 2 to 4 years}.
2 to 4 years: According to Piaget, children can use language and symbolism, play make-believe, distinguish between objects and thoughts, treat feelings and desires as more important than reality, use main object stimuli, manipulate symbols, and imitate in thought {pre-conceptual thought} {pre-operational stage}. They cannot make classes or sets and cannot use other viewpoints.
2 to 5 years: Child independence correlates with achievement {cognition development, 2 to 5 years}. Boys and girls are equally independent. Achievement motive remains at same level until adulthood.
2 to 5 years: Fears of stimuli or actual danger decrease, while fears of accidents, darkness, ghosts, and dreams increase {emotion development, 2 to 5 years}. Fear reactions, such as crying, panic, withdrawal, trembling, and clinging, decrease. Fear correlates with intelligence.
2 to 5 years: Children first play alone, then alongside peers, then cooperate with peers, and then organize play with peers {group play, toddler}. Friendships are first with children of same sex, age, and traits, followed by fewer and stronger friendships.
2 to 5 years: Heart rate slows, blood pressure increases, and respiration is deeper and slower {physical development, 2 to 5 years}.
2 to 8 years: Left-hemisphere damage before age 8 or 9 allows language acquisition, but with several months to three years delay {brain development, 2 to 8 years}.
25 months: Children that receive little affection stay frustrated, have tantrums, and are aggressive {emotion development, 25 months}. If mother goes away for day, children protest loudly but then accept others. If mother goes away longer, children become indifferent to mother.
25 months: Children can walk up and down stairs with no help {physical development, 25 months}.
29 to 30 months: Toddlers can use two nouns together {language development, 29 to 30 months}.
3 years: Children begin to know about minds and mental states {cognition development, 3 years}. Competitiveness starts. Children do not notice stimulus changes or single out stimulus parts.
36 months: Children can repeat words that they hear {echolalia}.
3 years: Children no longer need mother present {emotion development, 3 years}.
36 months: Children can use four-word sentences {language development, 36 months}. Sound articulation improves greatly. Verbal mediation begins. Children have 900-word vocabularies, can use 100 words, have frustration if not understood, use five-word phrases, have good understanding, and have adult grammar.
3 years: Boys and girls are same size, 0.95 meters and 15 kilograms {physical development, 3 years}. All baby teeth are present. Children can run and turn smoothly, jump up 30-centimeter stairs with both feet, stand on one foot for one second, build towers of 9 to 10 cubes, fold paper in half but not diagonally, and draw less repetitively. Children sleep 20% in REM sleep.
3 to 10 years: Average height does not differ between boys and girls {physical development, 3 to 10 years}. However, height variation for 10-year-old boys is 26 centimeters.
3 to 4 years: Children can understand described situations but cannot apply learning to actual situations {cognition development, 3 to 4 years}. They can perform Piaget's class inclusion task if it slightly changes. They can match objects explored by touch or vision. They construct coherent value systems, using model codes or people.
reasoning
They do not necessarily reason as expected, because context is more important to them, and premises can lack enough context. They can reason deductively about spontaneous activities. They can make comparisons that depend on transitive reasoning: if a = b, and if b = c, then a = c.
reality
Children cannot separate appearance, what something looks like, from reality, what it actually is. They know only real world and do not fantasize or pretend.
3 to 5 years: According to Piaget, young children cannot think that objects exist independently of sensory experience {cognition development, 3 to 5 years}. Young children cannot think about several objects simultaneously. Young children have no mental structures representing class hierarchies. Young-children thoughts are successive separate moments, with current one dominant. Children first learn possible viewpoints, then reasoning about relationships, then combining and ordering in physical world, and then combining and ordering mentally.
3 to 5 years: Children learn about narrative and fantasy and build sentence chains and trees {language development, 3 to 5 years}.
3 to 6 years: Hippocampus becomes mature, so memory can be long term {brain development, 3 to 6 years}. Brain growth is earlier than general body growth, so brain is 95% of adult size by age 6 years.
3 to 8 years: Familiar stimulus parts have labels {cognition development, 3 to 8 years}.
Only children older than 3.5 years can pass theory-of-mind tests {false-belief test}.
4 years: Brain is 80% of adult weight {brain development, 4 years}. Vertical exogenous fibers extend to cortex layer 3b. Layer 3a becomes functional. Limbic system begins.
4 years: Children know if other people can and cannot see and hear them {cognition development, 4 years}. Children can pretend. Children can report facts that they see or know. Children know that others have thoughts just as they do. Girls and boys perform the same on verbal, quantitative, and spatial tests. To identify objects requires many details.
4 years: Dependency is high but on peers, not parents {emotion development, 4 years}. Competitiveness is strong, especially among boys and in lower classes. Aggression does not correlate with competitiveness. Jealousy, fear, sensitiveness, and aggressiveness start to decline.
48 months: Children have 1500-word vocabularies {language development, 48 months}. Children can use 5.3 words in sentences and use compound sentences. Word inflection begins. Toddlers know most regular grammar rules but leave auxiliary words out. Children can name several objects from memory, name pictures containing several items, repeat 10-word sentences, count to four, and tell differences between geometric figures. Relative verbal ability stays the same until adulthood.
4 years: Children can run at different speeds with smooth changes, jump forward, skip but not hop, throw with just arm, draw circles and crosses but not diamonds, trace short straight lines, and fold paper diagonally {physical development, 4 years}. Children can detect differences in spatial orientation, such as reverse, tilt, and rotate, but not react to them. Boys and girls are same size, 1.02 meters and 17 kilograms. From four years on, muscles grow faster than other body parts.
4 to 5 years: Half of children stimulate their genitals {sex development, 4 to 5 years}. Children can show sexual play, voyeurism, and exhibitionism.
4 to 6 years: Nightmares peak, because anxiety is high and children cannot handle stress {emotion development, 4 to 6 years}.
4 to 7 years: According to Piaget, children can use intuitive thought, make classes, realize that objects belong in classes, use quantifiers, use no logic, and be still centering {cognition development, 4 to 7 years}. Measurement ability begins at four, and children can make same lengths as objects. At four and a half years old, children can use body to measure. At seven years old, children can use inanimate objects to measure.
4 to 7 years: Children cannot use interaction or no interaction between two variables to determine object properties, such as number, quantity, time, or space {conservation concept}.
4 to 10 years: Before age 10, children form informal groups {group play, 4 to 10 years}.
4 to 10 years: Growth rate slows slowly {physical development, 4 to 10 years}. Average growth is 5 centimeters per year.
5 years: Temporal-pole fissure is complete {brain development, 5 years}.
5 years: Children can organize memories, so they can recover from speaking interruptions {cognition development, 5 years}. Children can draw squares and triangles but not diamonds, trace long straight lines, draw people, recall 4 to 5 numbers immediately, and pick up tiny pellets and place them. Children have good balance, show handedness, act independently, dress themselves, use toilet alone, play alone unsupervised, solve small problems, imitate activities, and talk and think to themselves.
5 years: Children have well-defined personalities {emotion development, 5 years}. Approach-avoidance conflict is common, leading to gratification delay or inhibition. Quarrels are verbal and longer. Seeking attention and approval shows dependency, as do touching and clinging. Dependency in girls stays the same until age 14. Children like nurturance from opposite-sex parent more.
5 years: Children have 2000-word vocabularies {language development, 5 years}.
5 years: Boys and girls are same size, averaging 1.08 meters and 19 kilograms {physical development, 5 years}. Relative height at age five highly correlates with adult relative height. Reaction to infection is at lower temperature but lasts longer.
5 to 10 years: Immediate-memory capacity increases, impulsitivity decreases, and reflectivity increases, because children become more aware and fear making mistakes {cognition development, 5 to 10 years}. Other fears are darkness, aloneness, imaginary creatures, and dangerous animals. Perhaps, these fears relate to parental punishments. Morals and conscience develop.
6 years: Frontal-lobe, parietal-lobe, and occipital-lobe fissurations are mostly complete {brain development, 6 years}. Brain is 90% of adult weight. Parietal-lobe and occipital-lobe surface areas are complete. Layer 2 is functional. Neural connections maximize at age 6, and pruning is later.
6 years: Children learn genital shapes. Children learn ethnic-group identifications {cognition development, 6 years}. Children learn prejudice, mostly from parents. Grade-school children know that minds have beliefs, hopes, and desires. Boys can do mazes better. Girls use verbal strategies for solving such problems more than boys. Young children do not understand false beliefs and unreal photographs, because they cannot represent fantasies yet. More boys than girls have reading difficulties. Boys have more restlessness at school and are more difficult to teach.
6 years: Boys can match colored blocks {Koh's blocks} {Koh blocks} to patterns, and do spatial ability tests, better than girls.
6 years: Children have 2500-word vocabularies and can read {language development, 6 years}.
6 years: Children average 1.15 meters and 21 kilograms {physical development, 6 years}. Abdomen is flat. Brain is 90% of adult brain. First tooth is lost. Children can throw balls well, count up to 9, go through mazes, and react to orientation changes, because they have learned up-down and right-left.
6 to 7 years: Ability to sustain attention increases greatly, in all cultures {cognition development, 6 to 7 years}. Children learn sex as people category.
Children explore and stimulate their bodies and genitals {sex development, 6 years}. Such exploration and stimulation is necessary for normal psychological sexual development. Before puberty, both boys and girls typically masturbate and achieve orgasm.
Some children have fear of school {school phobia}. Children can have little inhibition, behave well, come from intact families, have not experienced long or frequent separations from home, and have parents that express great concern for them. Refusal to go to school is anxiety about leaving home, not fear of school. Children like elementary school up to fourth grade.
6 to 12 years: Attention shifts more often and faster {cognition development, 6 to 12 years}. Expectancies depend on situations. Children have more worries about mistakes. 25% of children have regular nightmares, and some have night terrors.
6 to 12 years: Boys initiate more aggression than girls, and their aggressions are longer {emotion development, 6 to 12 years}. Girls are more nurturing and protective than boys. School-age boys like nurturance from men better than from women. Other children do not like highly dependent children.
6 to 12 years: Limbs lengthen relative to trunk, blood pressure increases, and pulse decreases {physical development, 6 to 12 years}. Before 9 years old, boys are taller than girls, but, after 9, girls are taller. Boys' growth is two years behind girls' growth. Girls are taller than boys until age 15.
Lymphatic organs, such as tonsils and lymph nodes, grow greatly in early childhood. Boys have higher basal metabolism than girls and have greater vital capacity than girls, because androgens cause greater physical activity.
Adults tolerate wider boy behavior range {expectations based on sex, 12 years} {sex development, 12 years}. Parents allow boys to roam neighborhood and encourage girls to stay home. Boys play more outside, are more physically active, and play less with dolls. Boys' rooms contain more educational material and sports equipment than girls' rooms. Most children's books are about boys, men, and male animals. They show that boys are aggressive, constructive, helpful, active, and adventuresome. They show that girls are passive, immobile, and deferential.
7 to 8 years: At age seven, children can recreate mental states and reverse logical processes or transformations {reversibility concept}.
7 to 8 years: Children can notice stimulus parts {cognition development, 7 to 8 years}. Children can separate personal experiences from problem contexts.
7 to 8 years: Children can understand metaphors {language development, 7 to 8 years}. Speech articulation becomes as good as adults. Verbal mediation is well developed. Deaf children use imagery instead of sounds and have same ability to solve problems.
7 to 8 years: Children's morals depend on obedience to orders from adults {values development, 7 to 8 years}.
7 to 11 years: According to Piaget, children can perform concrete operations {serialization, Piaget}, relate objects by scale or quantity, include objects in classes, relate parts to wholes, play using logical rules, use flexible thinking, consider other views, communicate extensively, make mental representations, know relations, and understand relations among relatives {cognition development, 7 to 11 years}.
7 to 11 years: According to Piaget, children at this stage can perform concrete operations {serialization, development}.
8 years: Fear of death or parent death {death phobia}| peaks after children learn that death is irreversible.
8 to 11 years: Morals depend more on right and wrong, justice, equality, groups, and situations {values development, 8 to 11 years}. Conscience develops through identification with others and from fear of love or approval loss. Punishment can reduce moral-standard internalization.
9 to 11 years: Boys do not express interest in girls {sex development, 9 to 11 years}.
9 to 14 years: Adolescence begins earlier for boys than girls {physical development, 9 to 14 years}.
9 to 14 years: In early adolescence {pubescence}|, heart grows more rapidly. Boys lose fat, but girls keep same ratio. Ossification speeds up at puberty. Skin problems begin at pubescence.
9 to 17 years: Girls prefer to have attractive faces, no body hair, small frames, and moderate breasts {sex preference}. Boys prefer tallness, large muscles, and face and body hair.
9 to 17 years: Expectations for boys are strength, courage, activity, sports, ambition, and persistence {expectations based on sex, 9 to 17 years} {sex development, 9 to 17 years}. Parents allow boys more aggression. Expectations for girls are friendliness, good manners, neatness, emotion expression, and demureness. Parents allow girls more dependency and nurturing behavior. Girls use verbal aggression.
10 years: Frontal-lobe surface area is complete, and all fissuration is complete {brain development, 10 years}.
10 years: Vague outlines can suggest objects, and children can recall 6 to 7 numbers immediately {cognition development, 10 years}.
10 to 12 years: Growth rate increases rapidly, before slowing at 15 or 16 and then stopping at 17 or 19 years {physical development, 10 to 12 years}.
10 to 14 years: Same-sex gang behavior predominates {group play, 10 to 14 years}.
10 to 18 years: Groups are more structured but still short-lived {group play, adolescent}. Girls conform more. Low-status people conform more. Younger children conform more than older children. Adolescents like strong relationships. Adolescents have clique talking groups and activity groups. Adolescents have friends of same age, track, class, and interests. Adolescents tend to set up seemingly separate cultures, designed to exclude adults.
11 years: According to Piaget, children at this stage can perform formal operations, think abstractly, analyze, judge, reason, deduce, consider problems not related to reality, apply rules to things, and combine rules and generalize {combinative structure}. They can think about thinking, possibilities, self, future, and things not in experience.
11 years: Boys start to show interest in girls {sex development, 11 years}.
11 to 14 years: Brain-wave pattern is like adult {brain development, 11 to 14 years}.
11 to 15 years: Boys can experience ejaculation {nocturnal emission}| during sleep.
11 to 15 years: At 11, boys are slightly heavier, but, at 15, girls are heavier {physical development, 11 to 15 years}. Bone and muscle growth rate increases.
11 to 15 years: Sex organs mature {sex development, 11 to 15 years}. Puberty averages two and a half years later in males than in females.
boys
Boys typically start at age 13, peak at age 14, and decline at age 15.5. Boys can start as early as 9.5 years or as late as 13.5 years.
girls
Girls typically start at age 11, peak at age 12, and decline at age 13. Girls can start as early as 7.5 or as late as 11.5 years. Breast buds appear at age 11, as areola diameter increases and small mound appears. One or two years before menarche, breast enlarges, nipples project, uterus grows, and pubic hair appears. At age 13, with range from 11 to 15, menarche starts and pigmented pubic hair grows. Climate does not affect menarche time. Menarche time has not decreased much over history. Malnutrition can delay menarche. Fertility is one to three years after puberty.
attitudes
Adolescent sexual attitudes are aggressive, exciting, shameful, dangerous, pleasant, and sharing.
cause
Gonadotropin-releasing-hormone (GnRH) release from hypothalamus triggers puberty, causing pituitary to secrete hormones that affect testes or ovaries. Kiss-1-gene enzyme {kisspeptin} activates GPR54, which also affects puberty.
12 years: Except for prefrontal lobe, layer two functions {brain development, 12 years}. Alpha waves dominate EEG. Central association areas and frontal lobes can function. Reticular formation completes myelination at puberty.
12 years: TV viewing peaks {cognition development, 12 years}.
12 years: Children average 1.50 meters and 38.5 kilograms {physical development, 12 years}. Most permanent teeth are in. Lymphoid tissue grows steadily until 11 or 12, and then growth rate declines.
adolescence
Average boy starts adolescence. Just before puberty, forehead becomes higher and wider, mouth widens, lips become fuller, and chin juts out more.
During adolescence, average male loses subcutaneous fat and increases muscle bulk. Subcutaneous-fat growth rate slows only in girls.
Growth in shoulder width is greater in males. Growth in pelvic breadth is similar between sexes.
rate
Children with fast early growth usually finish growing earlier, while late developers finish growing later. Growth is regular.
12 to 14 years: Adolescents understand metaphors {language development, adolescent}.
Sexual organs and characteristics can mature {puberty}|.
Teenagers {adolescence}| can demand to be independent, adjust to peers, adjust to sex changes, prepare for jobs, and develop philosophies. Adolescents are ready to change themselves and try hard. Adolescent values are honesty, naturalness, tolerance, low activity, materialism, morals, consistency, and heroes. At 18, people choose vocations. Adolescence varies among cultures. Heredity, diet, climate, culture, and emotional influences start adolescence.
12 to 18 years: Girls perform better on verbal tests {cognition development, 12 to 18 years}. Boys perform better on quantitative and spatial tests. Girls do better in school until late adolescence. Adolescents become more curious about world and are eager for knowledge. Adolescents want knowledge based on their experiences.
12 to 18 years: Adolescents have many moods and instabilities, associated with rapid sexual development {emotion development, adolescent}.
13 years: Cerebellum is at adult weight {brain development, 13 years}. Substantia-nigra dark pigmentation is complete.
13 to 16 years: First menstrual period was at 16.5 years in 1840 and is at 13 now {sex development, 13 to 16 years}.
14 years: Prefrontal-lobe lower layers function {brain development, 14 years}. Cortex layers one and two function, except in prefrontal lobe. These layers affect association areas and short-and-long circuit reorganizations. Waking and sleeping EEGs show sudden transitions.
14 to 16 years: Boys experience first seminal-fluid discharge, either through masturbation or through spontaneous nocturnal emission {sex development, 14 to 16 years}. Adolescent girls rarely experience spontaneous orgasm during sleep. Many adolescent girls do not masturbate or feel need.
culture
Reading, adults, and peer groups typically provide information about orgasm and sexual arousal. Dating begins. Sexual consciousness and interest in opposite sex rise.
Boys' sexual interest focuses on overt sexual activity earlier than, and more than, girls' interest. Western society encourages adolescent males to be overtly sexual. It encourages adolescent females to be socially attractive but not overtly sexual.
homosexuality
Homosexual fantasies and/or physical contact can happen, in boys and girls. Boys are more likely to be sexually attracted to younger boys. Girls are more likely to be sexually attracted to older girls. Having juvenile overt physical or sexual homosexual contact does not affect adult homosexual or bisexual behavior.
15 to 18 years: Boys are heavier {physical development, 15 to 18 years}.
15 years: Boys' first orgasm typically happens {sex development, 15 years}. Boys average three orgasms per week from age 16 to 30. 50% of girls have orgasm before age 20, and 90% have orgasm by age 35. Girls average two orgasms per week from age 26 to 30.
17 years: Girls have mature bones {physical development, 17 years}.
17 to 20 years: Prefrontal-lobe layers three, four, five, and six function {brain development, 17 to 20 years}. Association areas are still developing.
18 years: Myelin is still forming in reticular formation and association areas {brain development, 18 years}.
Mature people {adult} are objective about selves, have history sense, know their roles, know others, accept others, have others accept them, have purposes, are self-actualizing, have self-control, and have self-knowledge.
Illiterate or inexperienced adults rely on context, rather than words, to understand communications {language development, adult}.
Speed and ability peak between late teens and late thirties and then gradually decline. Adult appearance depends on appearance at age 5 {physical development, adult}. Adult males average 12 centimeters taller than adult females. In last 150 years, children around world have grown to greater adult heights and have matured earlier. Adult height has increased by approximately 1 centimeter per decade.
At age 35, all brain parts are complete {brain development, adult}. Frontal lobes have myelin.
Growing old {aging, development} changes DNA, protein, hormones, cells, tissues, and organs.
causes
Autoimmunity or immune-system breakdown can cause aging. Pituitary hormone and/or thymosin decrease can cause aging. Thymus thymosin keeps immune system active. Structural-molecule changes, as collagen has more cross-links and stiffens, can cause aging.
effects
Aging impairments typically result from disease, trauma, or disuse, not age itself.
effects: biology
Brain deterioration causes most aging effects. Random brain activity increases. Serum globulin becomes higher. Fracture-healing rate decreases.
effects: behavior
Performance ability peaks at 26 and then slowly declines. Slower decision making, especially for tasks in which responses cause signals for next response, slows activities slightly. Older people pay attention to responses more, rather than to next task.
Older people learn facts and skills more slowly but do not forget more rapidly. Verbal ability peaks at 50 and sharply declines after 70.
effects: senses
Signals from sense organs to brain and among brain parts become weaker. Ability to understand speech does not decrease with age, unless people cannot hear frequencies below 1800 Hz, three octaves above middle C. Trauma causes most hearing loss. Aging causes reduced sensitivity to vibration and pain. Smell loses sensitivity.
Aging causes reduced fine-joint-movement sensitivity, reduced clear-focus distance, reduced resting pupil size, increased yellow eye pigment, reduced overall acuity, slight visual-field narrowing, color-discrimination loss, and increased glare susceptibility.
effects: personality
Personality has few trends with age. Adjusting to aging does not relate to health or wealth.
individual differences
Aging rate and effects differ among individuals, and differences become greater with age.
defenses
Aging defenses are apoptosis, suppressor genes, gene redundancy, DNA editing, RNA editing, DNA repair, anti-oxidant free-radical scavenging, defective-protein removal, and damaged-cell removal by immune system.
long life
Physical fitness, genetic factors, low mental pressure, low-fat diet, low-calorie diet, psychological well-being, and living in highlands can contribute to long life. Lowering body temperature and food-intake rate slows aging in animals.
theories
Mammals, even wild animals in zoos, age after adulthood. Perhaps, genetics determines aging, and childhood, sexual maturity, adulthood, and senescence involve separate genetic programs. Perhaps, aging results from diminished energy, slower repair, and increased damage. Perhaps, aging results from free-radical oxidation.
Species have age limits {age limit}. Age limits and population structure can maximize reproductive fitness. People can live to 130 years.
Oxygen-containing molecules can gain electrons, make free radicals, and react with cell molecules {anti-oxidant theory of aging}. Superoxide dismutase (SOD) returns oxygen-containing molecules to normal. Antioxidant vitamins can scavenge free radicals.
Lifetimes {lifespan} can increase by delaying reproduction.
Human cells can divide up to 50 times {aging, cell} {cell, aging}. All cells, except cancer cells, have programmed lifespans. Gene redundancies can affect cell lifespans.
diseases
Genes or accumulated defects can cause old-age diseases. Defects include frame-shift mutations and nucleic-acid-coding, transcription, translation, microsatellite, gene-expression, and post-translational-modification errors.
cell changes
In aging, neurons have more Nissl bodies, are larger, have more axons, have more synaptic bulbs, have more dendrites, and have more myelination. Nerve-fiber length, size, and compactness increase.
cell death
Cells first deteriorate, then become senescent, then stop dividing, and then die.
telomeres
Telomeres decrease in length with each replication. After telomeres reach threshold length, cells can have senescence.
chemicals
In aging, nucleic-acid-to-protein ratio changes. Somatic-cell DNA mutates. DNA-repair-mechanism efficiency decreases. Oxygen uptake decreases. Anti-oxidants have less effect. Lysosomes increase. Intestine calcium-ion transport decreases. Cholesterol excretion decreases.
chemicals: free radicals
DNA damage affects biological aging and Alzheimer's disease. Free radicals from mitochondria and other chemical reactions can damage DNA, but vitamin E binds free radicals.
chemicals: protein
In aging, enzymes can change. Cell amyloid deposits can increase. In amyloidosis, frame-shift mutations cause protein-folding errors.
chemicals: proteins and slower aging
Sirtuins can slow aging.
Mouse, worm, and fruitfly Daf protein is similar to human insulin. Mouse, worm, and fruitfly TOR gene repression slows aging by decreasing cell growth and regulating glucose metabolism.
Mouse, worm, and fruitfly Fox0 is similar to human IGF-1. Yeast, worm, and fruitfly TOR gene repression slows aging by decreasing cell growth and regulating glucose metabolism.
Fruitfly Methuselah protein is similar to human CD97 protein. Decreased fruitfly Methuselah protein slows aging by resisting stress and increasing neuron signaling.
Worm Clock (clk-1) protein is similar to human CoQ protein. Worm Clock gene repression slows aging by regulating CoenzymeQ synthesis.
Worm Amp-1 protein is similar to human AMPK protein. Increased Amp-1 protein slows aging by regulating stress responses and metabolism.
Decreased mouse and rat growth hormone slows aging by decreasing body size.
Decreased mouse P66Shc protein slows aging by decreasing free-radical creation.
Mouse catalase is similar to human CAT protein. Increased mouse catalase slows aging by changing hydrogen peroxide.
Mouse Prop1 or pit1 protein is similar to human Pou1F1 protein. Decreased mouse Prop1 or pit1 protein slows aging by regulating pituitary gland.
Increased mouse Klotho protein slows aging by regulating insulin, IGF-1, and vitamin D.
Yeast, worm, and fruitfly SIR2 gene makes sir2 protein. Humans SIRT1 gene makes sirt1 protein. Sirtuins {silent information regulators} {sirtuin} slow aging, by mediating stress responses and deacetylating histones to make DNA coil tighter and prevent extra DNA production. Low calorie intake, high salt, high heat, and low nitrogen intake can increase PNC1-gene production, remove nicotinamide, and increase sirtuins. Low calorie intake causes mitochondria to respire instead of ferment, making low NADH and high NAD and increasing sirtuins. Red-wine and knotweed have resveratrol, which increases sirtuins.
Glycosylation make products {advanced glycosylation endproducts} (AGE) that damage DNA, lipids, and proteins.
Small deposits {drusen} can be outside cells.
Species-specific germline genes {gerontogene} can affect aging rates or maximum lifespans.
Fatty proteins {lipofuscin} can be in cells.
Human fibroblasts in culture can only divide 50 times {replicative senescence} {replication limit}. For species, allowed-doubling number is proportional to lifespan.
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Date Modified: 2022.0225