In the primate retina, H1 horizontal cells form an electrically coupled network and receive convergent input from long- (L-) and middle- (M-) wavelength-sensitive cones. Using an <i>in vitro</i> preparation of the intact retina to record the light-evoked voltage responses of H1 cells, we systematically varied the L- and M-cone stimulus contrast and measured the relative L- and M-cone input strength for 137 cells across 33 retinas from three Old World species (<i>Macaca nemestrina, M. fascicularis</i>, and <i>Papio anubis</i>). We found that the L- and the M-cone inputs were summed by the H1 cell in proportion to the stimulus cone contrast, which yielded a measure of what we term L- and M-cone contrast gain. The proportion of L-cone contrast gain was highly variable, ranging from 25% to 90% [mean ± standard deviation, (60±14)%]. This variability was accounted for by retinal location within an individual, with the temporal retina showing a consistently higher percentage of L-cone gain, and by large overall variation across individuals, with the mean percentage of L-cone gain ranging from 32% to 80%. We hypothesize that the relative L- and M-cone contrast gain is determined simply by the relative number of L and M cones in the H1 cell’s receptive field and that the variability in L- and M-cone contrast gain reflects a corresponding variability in the mosaic of L and M cones.
© 2000 Optical Society of America
(330.0330) Vision, color, and visual optics : Vision, color, and visual optics
(330.1720) Vision, color, and visual optics : Color vision
(330.4270) Vision, color, and visual optics : Vision system neurophysiology
(330.5310) Vision, color, and visual optics : Vision - photoreceptors
(330.5380) Vision, color, and visual optics : Physiology
Dennis M. Dacey, Lisa C. Diller, Jan Verweij, and David R. Williams, "Physiology of L- and M-cone inputs to H1 horizontal cells in the primate retina," J. Opt. Soc. Am. A 17, 589-596 (2000)