Cortical representation of color is binocular.

It is widely believed that the cortical mechanisms of color vision are monocular because stereopsis is poor for isoluminant patterns. By measuring and comparing the chromatic tuning of binocular and monocular neurons in cortical areas V1 and V2 of macaque, we show that this is not the case. Not only are many color-preferring cells in early visual cortex well-driven binocularly, but their color preferences are unusually well-matched in the two eyes. The receptive fields of these neurons are well equipped to convey information about binocular surface color, but because they are insensitive to local spatial contrast they are ill-suited to convey information about stereoscopic depth. Our observations suggest that in early cortical processing, binocular depth and binocular surface color are represented by two different groups of neurons: one that encodes binocular spatial detail at the expense of binocular chromatic detail and another that does the reverse.