Synaptic contacts between red-sensitive cones and triphasic chromaticity horizontal cells in the turtle retina.

Using combined physiological and anatomical methods, we have shown that triphasic chromaticity horizontal cells (THC) in the turtle retina make ribbon synaptic contacts with about 20 cones, two-thirds were red-sensitive, while the rest were blue-sensitive. The response of THC to red flashes appeared to be generated via synapses from red-sensitive cones; this interpretation differs from those of the previous studies where only blue-sensitive cones were thought to make synaptic contacts with the THC.