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
electronic flashabout 5600
tungsten-halogen lamp3000
tungsten filament lamp2600
candle flame2000

Table C6 Prevalence (%) and classification of colour vision defects
anomalous trichromats
colour responseslight green deficiencyred deficiencyblue deficiency
colour responsegreen deficiency insensitive to redblue deficiency
neutral point498 nm 493 nm570 nm
cone monochromatrod monochromat
References in periodicals archive ?
Sparse and fine TH(+) nerve fibers in the NS group were scattered in the cortical layers, mainly in layer IV.
For a long time, scientists used to believe the mammalian cerebral cortex to be the anatomical cause of cognitive ability; it is made up of six cortical layers," said Sara Letzner from Ruhr-Universitat Bochum in Germany.
Because of the thickness of the cortical layers of this calvarial bone, graft material can be harvested from the external cortex leaving the structures inside the cranial cavity intact (Pensler & McCarthy, 1985; Cannella & Hopkins, 1990; Frodel et al.
Prior postmortem studies have led to the hypothesis that most cartridges across cortical layers 25 have a decreased level of GABA reuptake, presumably a compensatory mechanism for lower GABA signaling associated with the disorder.
Semaphorin 3A, which is expressed in descending gradients across cortical layers, was shown to serve as an attractant for newborn cortical neurons, guiding them to the upper cortical layers.
01) but a greater number of GFAP-positive astrocytes in all cortical layers as compared to control- treated animals (P less than 0.
Although most focuses of tissue rarefaction were located in the medial cortex, occasional focuses of tissue rare faction were observed in all the cortical layers.
Stoner and his colleagues used gene expression to examine cellular markers in each of the cortical layers as well as genes that are associated with autism.
4] Of the 3 cortical layers, zona fasciculata and glomerulosa predominate.
The remaining 3 cases of focal cortical dysplasia were marked by an absence of layer II, occasional large pyramidal-type neurons (neuronal cytomegaly) malpositioned in cortical layer I or superficial layer III, and a malalignment of pyramidal-type neurons within cortical layers III and V.
1--This drug has inhibitory activity on cell proliferation and differentiation of cerebellar cortical layers.