The relationship between simple and double opponent cells.

Little is known about the formation of double opponent cells (DOCs) from geniculate afferents. Three LGN cell types have been considered as DOC precursors. No simple wiring scheme based on these cell types is consistent with the available evidence. The color and luminance multiplexed signal of P beta ganglion cells (Type I receptive fields) contains the information necessary to construct DOCs, provided that filtering operations can separate the two signals. Electrophysiological and anatomical evidence is consistent with Type I cells being filtered prior to the formation of DOCs. Cortical Type II and Type III cells can also be created by filtering.