Receptive field properties of color opponent neurons in the cat lateral geniculate nucleus.
Most nonprimate mammals possess dichromatic ("red-green color blind") color vision based on short-wavelength-sensitive (S) and medium/long-wavelength-sensitive (ML) cone photoreceptor classes. However, the neural pathways carrying signals underlying the primitive "blue-yellow" axis of color vision in nonprimate mammals are largely unexplored. Here, we have characterized a population of color opponent (blue-ON) cells in recordings from the dorsal lateral geniculate nucleus of anesthetized cats. We found five points of similarity to previous descriptions of primate blue-ON cells. First, cat blue-ON cells receive ON-type excitation from S-cones, and OFF-type excitation from ML-cones. We found no blue-OFF cells. Second, the S- and ML-cone-driven receptive field regions of cat blue-ON cells are closely matched in size, consistent with specialization for detecting color contrast. Third, the receptive field center diameter of cat blue-ON cells is approximately three times larger than the center diameter of non-color opponent receptive fields at any eccentricity. Fourth, S- and ML-cones contribute weak surround inhibition to cat blue-ON cells. These data show that blue-ON receptive fields in cats are functionally very similar to blue-ON type receptive fields previously described in macaque and marmoset monkeys. Finally, cat blue-ON cells are found in the same layers as W-cells, which are thought to be homologous to the primate koniocellular system. Based on these data, we suggest that cat blue-ON cells are part of a "blue-yellow" color opponent system that is the evolutionary homolog of the blue-ON division of the koniocellular pathway in primates.
Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary. peter.buzas@aok.pte.hu
Péter
P
Buzás
Péter
P
Kóbor
Zoltán
Z
Petykó
Ildikó
I
Telkes
Paul R
PR
Martin
László
L
Lénárd
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001931:Brain Mapping; D002415:Cats; D003118:Color Perception / Q000502:physiology*; D004594:Electrophysiology; D005260:Female; D005829:Geniculate Bodies / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation