Theory of orientation tuning in visual cortex.

AUTOR(ES)

Ben-Yishai, R

RESUMO

The role of intrinsic cortical connections in processing sensory input and in generating behavioral output is poorly understood. We have examined this issue in the context of the tuning of neuronal responses in cortex to the orientation of a visual stimulus. We analytically study a simple network model that incorporates both orientation-selective input from the lateral geniculate nucleus and orientation-specific cortical interactions. Depending on the model parameters, the network exhibits orientation selectivity that originates from within the cortex, by a symmetry-breaking mechanism. In this case, the width of the orientation tuning can be sharp even if the lateral geniculate nucleus inputs are only weakly anisotropic. By using our model, several experimental consequences of this cortical mechanism of orientation tuning are derived. The tuning width is relatively independent of the contrast and angular anisotropy of the visual stimulus. The transient population response to changing of the stimulus orientation exhibits a slow "virtual rotation." Neuronal cross-correlations exhibit long time tails, the sign of which depends on the preferred orientations of the cells and the stimulus orientation.

Documentos Relacionados

• Stimulus-specific neuronal oscillations in orientation columns of cat visual cortex.
• A linear model fails to predict orientation selectivity of cells in the cat visual cortex.
• Continuity of orientation columns between superficial and deep laminae of the cat primary visual cortex.
• Mechanisms of inhibition in cat visual cortex.
• Spatial frequency tuning of single units in macaque supragranular striate cortex.