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.
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Date Modified: 2022.0225