PRINCIPLES UNDERLYING SENSORY MAP TOPOGRAPHY IN PRIMARY VISUAL CORTEX

The primary visual cortex contains a detailed map of the visual scene, which is represented according to multiple stimulus dimensions including spatial location, ocular dominance and orientation. The maps for spatial location and ocular dominance originate from the spatial arrangement of thalamic axons in cortex. However, the origin of the other maps remains unclear. Here we demonstrate that the cortical maps for orientation, direction and retinal disparity are all strongly related to the organization for spatial location of light (ON) and dark (OFF) stimuli, an organization that we show is OFF-dominated, OFF-centric and runs orthogonal to ocular dominance columns. Because this ON/OFF organization originates from the clustering of ON and OFF thalamic afferents in visual cortex, we conclude that all main features of cortical topography, including orientation, direction and retinal disparity, follow a common organizing principle that arranges thalamic axons with similar retinotopy and ON/OFF polarity in neighboring cortical regions.