Figure 13.

Retinal circadian clock increases receptive field size and sensitivity of cones to dim light by enhancing rod-cone coupling at night. (A) Under dark-adapted conditions, the average cone light response threshold (log intensity required to elicit a 0.5 mV response) was significantly higher during the day and subjective day than during the night and subjective night. (B) Average normalized response amplitudes of dark-adapted cones plotted against stimulus radius for a stimulus of intensity -5 logI_o, indicates that the receptive field size of cones is larger at night (filled circles) than in the day (open circles). Error bars indicate SEM. Modified from Ribelayga et al. (2008).