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.
4-Zoology-Organ-Nerve-Brain-Cerebrum
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Date Modified: 2022.0225