Spectral opponency of on-type ganglion cells and the blue preference of Rana pipiens.

Spectrally opponent processes of ON-type retinal ganglion cells and the blue preference behavior were identified by parallel physiological and behavioral experiments in Rana pipiens. Spectral opponency of retinal ON-units was measured by recording from optic nerve terminals in the anterior thalamus, while the retina was stimulated by combinations of monochromatic stimuli. Spectral opponency of the blue preference was determined in a Y-maze, using similar combinations of monochromatic stimuli. The opponent processes of the ON-units and blue preference are similar in the spectral ranges of excitatory and inhibitory effects. In both cases the spectral opponency can be described as short wavelength excitation and long wavelength inhibition. The data suggest that the short wavelength excitation is based, at least in part, on the green rod (P432) channel, while the long wavelength inhibition is caused, at least in part, by stimulation of the principal and/or single cone (P580) channel. A model is presented to show how receptor interactions may encode this spectrally opponent process. The results support the hypothesis that the blue preference is dependent on information supplied to the anterior thalamus by ON-type retinal ganglion cells.