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
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
It usually appears as gradually raised areas of inflated skin covered with silvery-white scaly skin, while the top upper cortical layers peel easily, the lower ones are much more cohesive, this explains the reason behind the severe dryness, itching, swelling, and pain which most of patients' experience.
Phosphorylated tau aggregates in cortical layers II and III and hippocampal CA2 and CA4 regions are supportive of diagnosis of CTE.
To investigate which cortical layers of V1 are responsible for this regulation, we performed immunohistological stainings with the neuronal activity marker c-fos [29-31] in V1.
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., 1993; Hwang et al, 2000; Smolka et al.; de Souza Fernandes et al.).
NPY+-derived cells could be found in all cortical layers; transcription factor FOXA2 is critical for midbrain DA neuron development while coexpressions of the floor plate (FP) marker FOXA2 and the roof plate marker LMX1A are as well required.
After, all 3D-reconstructed sections were stained with the Nissl method to reveal the architecture of cortical layers. The devices were connected to a desktop computer running the Neurolucida software (MBF Bioscience, USA), thereby allowing for the recording and analysis of x, y, and z coordinates of digitized points.
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.
Here it was shown that the number of GFAP- immunoreactive astrocytes was increased in all cortical layers upon ethanol exposure, which was especially obvious in layers III and V, corresponding to the loss of neurons in these layers.