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Orientation column
About: Orientation column is a research topic. Over the lifetime, 1142 publications have been published within this topic receiving 130169 citations.
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TL;DR: It is reported here that ganglion cells near the fovea were allocated 3.3 to 5.9 times more cortical tissue than more peripheral ones, and it is concluded that the cortical representation of the most central retina is much greater than expected from the density of its ganglions.
Abstract: The retinal fovea, which corresponds to the central degree or so of vision, is spatially over-represented in the visual cortex. It is about 0.01% of retina area, but at least 8% of the striate cortex. Does this simply reflect an equivalently uneven distribution of ganglion cells in the retina, or is the cortical representation of the fovea preferentially expanded? The answer hinges on the resolution of long-standing discrepancies between the retinal and cortical magnification factors. We approached the problem in a different way, using a retrograde transneuronal tracer from cortex to retina to relate directly the number of ganglion cells projecting to marked areas of striate cortex. We report here that ganglion cells near the fovea were allocated 3.3 to 5.9 times more cortical tissue than more peripheral ones, and conclude that the cortical representation of the most central retina is much greater than expected from the density of its ganglion cells.
181 citations
TL;DR: It is concluded that, since simple cells are unresponsive to noise, they cannot provide the sole input to complex cells, and tells against the hypothesis that they act as a second stage in the abstraction of edge-orientation in cortical information-processing.
Abstract: The responsiveness of 254 simple and complex striate cortical cells to various forms of static and dynamic textured visual stimuli was studied in cats, lightly anaesthetised with N2O/O2 mixtures supplemented with pentobarbitone.
180 citations
TL;DR: The estimates confirmed previous reports suggesting that the ensembles of spiny L4 and thick-tufted pyramidal neurons emit the major fraction of APs of a column, and derived the layer-specific action potential output of a projection column.
Abstract: This is the second article in a series of three studies that investigate the anatomical determinants of thalamocortical (TC) input to excitatory neurons in a cortical column of rat primary somatosensory cortex (S1). Here, we report the number and distribution of NeuN-positive neurons within the C2, D2, and D3 TC projection columns in P27 rat somatosensory barrel cortex based on an exhaustive identification of 89,834 somata in a 1.15 mm(3) volume of cortex. A single column contained 19,109 ± 444 neurons (17,560 ± 399 when normalized to a standard-size projection column). Neuron density differences along the vertical column axis delineated "cytoarchitectonic" layers. The resulting neuron numbers per layer in the average column were 63 ± 10 (L1), 2039 ± 524 (L2), 3735 ± 905 (L3), 4447 ± 439 (L4), 1737 ± 251 (L5A), 2235 ± 99 (L5B), 3786 ± 168 (L6A), and 1066 ± 170 (L6B). These data were then used to derive the layer-specific action potential (AP) output of a projection column. The estimates confirmed previous reports suggesting that the ensembles of spiny L4 and thick-tufted pyramidal neurons emit the major fraction of APs of a column. The number of APs evoked in a column by a sensory stimulus (principal whisker deflection) was estimated as 4441 within 100 ms post-stimulus.
180 citations
TL;DR: It is reported that in the squirrel monkey, as in the cat, pairs of cells < or = 5 mm apart can show correlated firing, and this suggests that the correlations reflect not only permanent connections between cells with similar receptive fields, but in addition may encode information that the activating stimuli are continuous or part of a single object.
Abstract: 1. This work explores a mechanism that the brain may use for linking related percepts. It has been proposed that temporal relationships in the firing of neurons may be important in indicating how t...
180 citations
TL;DR: The inferior temporal cortex of 6 macaques was injected with horseradish peroxidase and HRP-labeled cells were found throughout IT cortex itself and in the regions of posterior prestriate cortex that receive direct projections from striate cortex.
179 citations