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.
Biological Sciences>Zoology>Organ>Nerve>Brain>Cerebrum>Occipital Lobe
4-Zoology-Organ-Nerve-Brain-Cerebrum-Occipital Lobe
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Date Modified: 2022.0224