cortical column


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column, cortical 

In the visual cortex, neurons with similar properties are arranged in columns (about 2 mm high) perpendicular to the surface of the cortex. The columns traverse the six cortical layers until they reach the white matter. Neurons throughout a column respond either to stimuli oriented at the same angle (orientation column) or to the inputs from the same eye (ocular dominance column, ocular dominance slab). A neighbouring column will then have neurons responding to a slightly different orientation from the one next to it and perhaps the same eye or the other eye. Neurons in layer 4 represent an exception, as they may respond to any orientation or to one eye only. Strabismus in early childhood disrupts the development of ocular dominance columns, thus preventing the development of depth perception. See visual area; blobs; hypercolumn.
Table C5 Approximate colour temperature (in K) of some light sources
clear blue sky12000-26000
overcast sky6600
sun5000-6000
electronic flashabout 5600
moonlight4000
tungsten-halogen lamp3000
tungsten filament lamp2600
candle flame2000

Table C6 Prevalence (%) and classification of colour vision defects
anomalous trichromats
deuteranomalprotanomaltritanomal
male4.6%1%0.0001%
female0.35%0.03%unknown
colour responseslight green deficiencyred deficiencyblue deficiency
dichromats
deuteranopeprotanopetritanope
male1%1.1%0.005%
female0.01%0.01%0.003%
colour responsegreen deficiency insensitive to redblue deficiency
neutral point498 nm 493 nm570 nm
monochromats
cone monochromatrod monochromat
unknown0.003%
References in periodicals archive ?
A vertically organized series of connected neurons that form a brain circuit, the cortical column is considered the elementary building block of the cortex, the part of the brain that is responsible for many of its higher functions.
This is the first complete 3D reconstruction of a realistic model of a cortical column," said Marcel Oberlaender, PhD, first author on the study.
In addition to recreating the structure of the cortical column, the study also sheds significant light on the function of its constituent neurons, and the relationship between their functionality and structure.