Ganglion cells of a short-wavelength-sensitive cone pathway in New World monkeys: Morphology and physiology
We have studied the morphology and physiology of retinal ganglion cells of a short-wavelength-sensitive cone (SWS-cone) pathway in dichromatic and trichromatic New World anthropoids, the capuchin monkey (Cebus apella) and tufted-ear marmoset (Callithrix jacchus). In Old World anthropoids, in which males and females are both trichromats, blue-ON/yellow-OFF retinal ganglion cells have excitatory SWS-cone and inhibitory middle- and long-wavelength-sensitive (MWS- and LWS-) cone inputs, and have been anatomically identified as small-field bistratified ganglion cells (SB-cells) (Dacey & Lee, 1994). Among retinal ganglion cells of New World monkeys, we find SB-cells which have very similar morphology to such cells in macaque and human; for example, the inner dendritic tree is larger and denser than the outer dendritic tree. We also find blue-on retinal ganglion cells of the capuchin to have physiological responses strongly resembling such cells of the macaque monkey retina; for example, responses were more sustained, with a gentler low frequency roll-off than MC-cells, and no evidence of contrast gain control. There was no difference between dichromatic and trichromatic individuals. The results support the view that SWS-cone pathways are similarly organized in New and Old World primates, consistent with the hypothesis that these pathways form a phylogenetically ancient color system.(Received December 18 1997)
(Accepted August 31 1998)
Key Words: Small-field bistratified ganglion cells; Blue-on ganglion cells; SWS-cones; Cebus apella; Callithrix jacchus.
c1 Correspondence and reprint requests to: Luiz Carlos de Lima Silveira, Universidade Federal do Pará, Centro de Ciências Biológicas, Departamento de Fisiologia, 66075-900 Belém, Pará, Brazil.