Stimulus dependent colour specificity of monkey lateral geniculate neurones

From six flaxedilized rhesus monkeys neuronal activity of 75 cells in the dorsal, and 45 cells in the ventral layers of the lateral geniculate body was recorded. Responses to large fields switched on and off, to moving slits, and to moving spots were obtained for several wavelengths. In the dorsal layers, colour selectivity was strong for large field stimuli but weak for moving spots. Residual colour selectivity for spots was more evident for smaller eccentricities. In comparison, ventral layer cells were less colour selective for all stimuli used. Large field responses were weak, they often consisted of a sequence of excitation and inhibition. The subdivision of the dorsal cells into different colour opponency types based on large field responses is compared to the subdivision based on centre and surround functions. Results are compared to colour responses in retina and visual cortex, and the tonic and phasic cell type subdivision is discussed.