Invited Session II: Retinal mechanisms mediating vision: The S-cone connectome of the primate retina

Abstract

Trichromatic humans have three types of cone photoreceptor: L-, M- and S-cones, which are tuned to long-, medium- and short-wavelength light, respectively. We know the least about the pathways carrying signals from S-cones because they are very rare and make up less than 10% of all cones. Past research has focused primarily on small bistratified ganglion cells that compare the outputs of S-cones to the summed outputs of L- and M-cones (S vs. L+M). I will review our recent efforts to comprehensively map S-cone circuitry within the macaque central retina using serial block-face scanning electron microscopy. We identified a surprising diversity of S-cone ON and OFF pathways, each with the same spectral signature: S vs. L+M. In total, the primate retina conveys this one spectral signal to the brain along at least five parallel pathways. Our results challenge classic color vision models that can only account for a single S vs. L+M pathway and demonstrate how our visual systems use color information for far more than just color perception.