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.
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Date Modified: 2022.0225