Studies of color perception have led to mechanistic models of how signals from cone-opponent retinal ganglion cells are integrated to generate color appearance. But it is not known where or how these hypothesized mechanisms occur in the brain. Here we show that cone opponent signals transmitted from the retina to primary visual cortex (V1) are integrated through highly organized circuits within V1 to generate the color opponent mechanisms that underlie color appearance. Combining intrinsic signal optical imaging (ISI) and 2-photon calcium imaging (2PCI) at single cell resolution, we demonstrate cone-opponent functional domains (COFDs) that combine L/M cone-opponent and S/L+M cone-opponent signals in precisely the combinations predicted from psychophysical studies of color perception. These give rise to an orderly organization of hue preferences of the neurons within the COFDs and the generation of hue "pinwheels". COFDs occupy regions corresponding to both high and low cytochrome oxidase intensity ("blobs" and "interblobs") but have a bias toward blobs. Thus, neural circuits in the primary visual cortex establish the boundary conditions for color opponency and unique hues.
bioRxiv Subject Collection: Neuroscience