Figure 1.

Progressive deficits in pupillary responses to light in R6/2 mice. A single light exposure (10 s, 470 nm) was tested at five different irradiances (9.3, 10.5, 11.7, 12.9 and 14.6 log quanta/cm²/s) to test consensual pupillary responses. (A–E) Phase response curves to light irradiance are shown from wild type (WT, black symbols and solid line) and R6/2 (white symbols and dashed line) mice at 9, 12, 15, 18 and 20 weeks. (F) Representative images of pupil size from R6/2 and WT mice at 20 weeks, recorded before the light stimulus in total darkness (dark) and at maximal constriction in response to a 10-s light exposure at 9.3, 10.5, 11.7, 12.9 and 14.6 log quanta/cm²/s, and 10 min after application of carbachol (Carb). Data shown in A-E are the mean maximal pupil constriction observed following light exposure from 19 to 20 mice ± SEM. Curves are fitted to a sigmoid function. Where error bars are not visible, they are obscured by the symbols. *P < 0.05, **P < 0.01.