Orientation Contrast Sensitivity from Long-range Interactions in Visual Cortex

Recently Sillito and coworkers (Nature 378, pp. 492, 1995) demonstrated that stimulation beyond the classical receptive field (cRF) can not only modulate, but radically change a neuron's response to oriented stimuli. They revealed that patch-suppressed cells when stimulated with contrasting orientations inside and outside their cRF can strongly respond to stimuli oriented orthogonal to their nominal preferred orientation. Here we analyze the emergence of such complex response patterns in a simple model of primary visual cortex. We show that the observed sensitivity for orientation contrast can be explained by a delicate interplay between local isotropic interactions and patchy long-range connectivity between distant iso-orientation domains. In particular we demonstrate that the observed properties might arise without specific connections between sites with cross-oriented cRFs.