Topic
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 demonstrated that the integration of local flanking elements with a central stimulus can occur as early as 80 ms in human visual cortex, but this includes processes occurring at longer latencies and appears to involve both striate and extrastriate visual areas.
36 citations
TL;DR: This progression in ocular dominance from ipsilateral to contralateral visual field agrees well with the distribution of X-cells about the nasotemporal division and the dynamic pattern of visual stimulation around a moving animal, the optic flow field.
Abstract: 1. Binocularity and receptive-field type of cortical neurons were assessed relative to the cortical layer in which the neurons were recorded and to receptive-field position in the visual field. 2. ...
36 citations
TL;DR: It is demonstrated that functions that oscillate more than once do not produce maps closely resembling those seen biologically, which strongly suggests that local lateral connections in visual cortex oscillate only once and have the form of a Mexican hat.
Abstract: Maps of ocular dominance and orientation in primary visual cortex have a highly characteristic structure. The factors that determine this structure are still largely unknown. In particular, it is unclear how short-range excitatory and inhibitory connections between nearby neurons influence structure both within and between maps. Using a generalized version of a well-known computational model of visual cortical map development, we show that the number of excitatory and inhibitory oscillations in this interaction function critically influences map structure. Specifically, we demonstrate that functions that oscillate more than once do not produce maps closely resembling those seen biologically. This strongly suggests that local lateral connections in visual cortex oscillate only once and have the form of a Mexican hat.
36 citations
TL;DR: It is concluded that, once stimulation parameters are adjusted for the small volume of the rat brain, the use of antidromic techniques may be an effective strategy to differentiate among projection neurons comprising different local circuits in supra- and infragranular circuits.
Abstract: Physiological studies of the rodent somatosensory cortex have consistently described considerable heterogeneity in receptive field properties of neurons outside of layer IV, particularly those in layers V and VI. One such approach for distinguishing among different local circuits in these layers may be to identify the projection target of neurons whose axon collaterals contribute to the local network. In vivo, this can be accomplished using antidromic stimulation methods. Using this approach, the axonal conduction properties of cortical efferent neurons are described. Four projection sites were activated using electrical stimulation: (1) vibrissal motor cortex, (2) ventrobasal thalamus (VB), (3) posteromedial thalamic nucleus (POm), and (4) cerebral peduncle. Extracellular recordings were obtained from a total of 169 units in 21 animals. Results demonstrate a close correspondence between the laminar location of the antidromically identified neurons and their anatomically known layer of origin. Axonal properties were most distinct for corticofugal axons projecting through the crus cerebri. Corticothalamic axons projecting to either VB or POm were more similar to each other in terms of laminar location and conduction properties, but could be distinguished using focal electrical stimulation. It is concluded that, once stimulation parameters are adjusted for the small volume of the rat brain, the use of antidromic techniques may be an effective strategy to differentiate among projection neurons comprising different local circuits in supra- and infragranular circuits.
36 citations
TL;DR: Three computational rules are sufficient to generate model cortical maps that simulate the interrelated structure of cortical ocular dominance and orientation columns: a noise input, a spatial band pass filter, and competitive normalization across all feature dimensions.
35 citations