Abstract
Three cell types account for 95% of ganglion cells which form the optic nerve. Each of these cell types is presumably specialized to carry specific information about the visual stimulus. There is agreement that three opponent circuits (blue/yellow, red/green, and black/white) underlie human color vision. One logical hypothesis is that each of the three ganglion cell types is responsible for one of the three opponent circuits. However, a number of observations seem inconsistent with this theory. Alternatively, we propose that midget ganglion cells are responsible for all three opponent circuits. Midget ganglion cells in the center of the retina have well defined differences in their connectivity to cones when compared to midget cells in the periphery, while small bistratified ganglion cells have stereotyped chromatic connectivity at all retinal eccentricities. Thus, if midgets are the basis for blue/yellow color vision, there should be predictable changes in hue perception when comparing an object viewed straight on to one seen in peripheral vision. The World Color Survey (WCS) consists of 320 chips with 40 different hues of eight different lightness values. Subjects viewed all 320 chips twice, once in the periphery and once in the central retina. In the periphery many more chips were perceived as white, fewer chips were viewed as green or purple, and the position in color space that is neither blue nor yellow was shifted. The results are consistent with the hypothesis that midget cells and not small bistratified ganglion cells may be the neural substrate for blue/yellow color vision.
Supported by the National Institutes of Health grants R03EY014056, EY09303, EY09620, T32EY014537, an NEI Core Grant for Vision Research EY01981, the Harry J. Heeb Foundation, and Research to Prevent Blindness.