Figure 1

Imaging and visual stimuli setup for mapping retinotopy and color in the mouse V1. (a) Opsin sensitivity functions for 3 different types of opsins found in rod and cone photoreceptors. Rhodopsin peaks at 498 nm, while cone S-opsin and M-opsin peak at 360 nm and 508 nm, respectively. 2 mouse genotypes were used: wild-type and Gnat1^−/−, which is a rod-deficient transgenic strain. (b) Illustration of cone S/M-opsin expression gradient in mouse retina (left) versus rhodopsin expression (right). Ventral retina (upper visual field) expresses predominantly S-opsin while dorsal retina (lower visual field) expresses predominantly M-opsin. Rods are uniformly expressed throughout retina. (c) Rear projection of visual stimuli using two monochromatic projectors, near-UV (nUV) and green. Screen color depicts corresponding S/M-opsin expression in mouse’s retina. (d) Measures of the display’s spectral radiance at three viewing angles. Uniformity is required for controlled light adaptation across the retinotopy. Below are the stimuli used to map retinotopy. (e) A total of 6 background light levels were used to adapt the retina, with each level scaling the spectral radiance by a factor of 2. Below is an illustration of the adaptation paradigm. Prior to a block of test trials with drifting gratings, the retina was adapted for 10 min by the midpoint (i.e. “gray level”) of the test trials. (f) Drifting gratings were calibrated to oscillate along one of three axes in S and M cone-opsin space: S, M, and S + M. The sine-wave insets indicate relative green and nUV LED amplitude and phase used for each of the three color axes. Below is an illustration of a stimulus paradigm for measuring color preference, where each trial showed a different color at a given adaptation level.