Horizontal cells of the primate retina: cone specificity without spectral opponency.
The chromatic dimensions of human color vision have a neural basis in the retina. Ganglion cells, the output neurons of the retina, exhibit spectral opponency; they are excited by some wavelengths and inhibited by others. The hypothesis that the opponent circuitry emerges from selective connections between horizontal cell interneurons and cone photoreceptors sensitive to long, middle, and short wavelengths (L-, M-, and S-cones) was tested by physiologically and anatomically characterizing cone connections of horizontal cell mosaics in macaque monkeys. H1 horizontal cells received input only from L- and M-cones, whereas H2 horizontal cells received a strong input from S-cones and a weaker input from L- and M-cones. All cone inputs were the same sign, and both horizontal cell types lacked opponency. Despite cone type selectivity, the horizontal cell cannot be the locus of an opponent transformation in primates, including humans.
Dacey
D M
DM
Department of Biological Structure, University of Washington, Seattle 98195-7420, USA.
Lee
B B
BB
Stafford
D K
DK
Pokorny
J
J
Smith
V C
VC
D000818:Animals; D003118:Color Perception / Q000502:physiology*; D003712:Dendrites / Q000648:ultrastructure; D006801:Humans; D007395:Interneurons / Q000166:cytology / Q000502:physiology*; D008252:Macaca fascicularis; D008253:Macaca mulatta; D008254:Macaca nemestrina; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D015398:Signal Transduction; D014795:Visual Pathways