Origins of Cross-Orientation Suppression in the Visual Cortex.

Citation Info

BW Li, JK Thompson, T Duong, MR Peterson, RD Freeman (2006)
Origins of Cross-Orientation Suppression in the Visual Cortex.
Journal of Neurophysiology. 96: 1755-1764

 

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Abstract

The response of a neuron in striate cortex to an optimally oriented stimulusis suppressed by a superimposed orthogonal stimulus. The neuralmechanism underlying this cross-orientation suppression (COS) mayarise from intracortical or subcortical processes or from both. Recentstudies of the temporal frequency and adaptation properties of COSsuggest that depression at thalamo-cortical synapses may be theprincipal mechanism. To examine the possible role of synaptic depression in relation to COS, we measured the recovery time course ofCOS. We find it too rapid to be explained by synaptic depression. Wealso studied potential subcortical processes by measuring single cellcontrast response functions for a population of LGN neurons. Ingeneral, contrast saturation is a consistent property of LGN neurons.Combined with rectifying nonlinearities in the LGN and spike threshold nonlinearities in visual cortex, contrast saturation in the LGN canaccount for most of the COS that is observed in the visual cortex.