Cone mechanisms and their colour-opponent interaction in monkeys and cat

Cone mechanisms and colour opponency were investigated in 108 recordings from tonic ganglion cells of the rhesus monkey retina and 265 recordings from ganglion cells of the cat retina. Colour-opponent cells input from short and longer wavelength sensitive cones can be found in both species in about equal proportions (6-8%). Although cells with opponency between middle and long-wavelength sensitive cones are very common in monkey (49%), they are rare in the cat (4%); usually the opponency of the latter can only be detected with strong chromatic adapting lights suppressing the dominant mechanism, while in monkey colour opponency is usually revealed under neutral adapting conditions. These differences between both species in processing chromatic stimuli can help to explain certain types of colour vision deficiencies in man.