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Dennis Dacey, Orin Packer, Jan Verweij, Julie Schnapf; Blue-Yellow opponent receptive field structure of primate S-cones. Journal of Vision 2007;7(15):5. doi: 10.1167/7.15.5.
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© ARVO (1962-2015); The Authors (2016-present)
Previous recordings from primate long (L) and middle (M) wavelength cones reveal a receptive field surround that transmits a mixed L and M cone signal to both cone types. Thus for L and M cones there is no basis for cone type selective wiring at the level of the cone synapse. In this study we targeted the sparse S cones to test the hypothesis that S cones receive negative feedback from L and M cones. S cones were reliably identified in vitro by small inner segment diameters and physiologically with stimuli that modulated light absorption in L, M, or S cone photopigment. S cone receptive fields were characterized from spots, annuli, and drifting sinusoidal gratings that modulated either S or L+M cone responses. Under voltage clamp S cones showed not only the expected inward current (hyperpolarization) to S cone isolating stimuli but also showed an outward current (depolarization) to L+M cone modulation. The spatial structure of the L+M cone surround is currently being investigated but preliminary data suggest a diam. circa 300 microns indicating that the S cone is both spatially and spectrally opponent and that the critical locus for S vs L+M cone opponency resides at the photoreceptor synapse.
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