Color Processing in the Retina
We’ve looked at lateral interactions mediated by horizontal cells in the OPL and amacrine cells in the IPL. There is a straight-through pathway with less lateral interaction and this pathway tends to code for color. A cone photoreceptor will synapse extensively onto a so-called cone bipolar (also carrying the evocative name “midget bipolar”) which in turn passes information to the dendrites of a ganglion cell.
Ganglion cells which receive information via bipolar cells from cone photoreceptors have color-opponent receptive fields. That is, if the receptive field center depolarizes to red light, the receptive field surround hyperpolarizes to green light. If the receptive field center hyperpolarizes to yellow light, then the surround depolarizes to blue light.