A, Dim flash ERG responses. Mice were dark adapted overnight, and ERGs were recorded. Thin curve, G38D/Tα−/− mice; medium curve, G38D/Tα+/− mice; bold curve, wild-type mice. Flashes were estimated to produce between 4 × 10−1 (dimmest) to 4 × 102 (brightest) photoisomerisations per rod. B, Recovery after a bright flash. Paired flash analysis was used to measure recovery of the rod photocurrent after a bright conditioning flash that caused ∼2 × 105 photoisomerisations per rod. The probe flash was identical to the conditioning flash. C, Recovery after a very bright flash. Paired flash analysis was used to measure recovery of the rod photocurrent after a bright conditioning flash that bleached 10–20% of rhodopsin in the retina. The probe flash stimulated ∼2 × 105 photoisomerisations per rod. WT, Wild type.