Decreased contrast sensitivity in nob mice. A: responses to 6 different contrasts of example cells in WT and nob mice. Black, solid lines indicate a Naka-Rushton fit. B: average of normalized contrast tuning curves, showing a rightward shift in nob mice (WT, n = 30, nob, n = 50 cells). C: larger half-saturation contrast in nob compared with WT. D: slope of the contrast response curve (determined at 20% of max response) is lower in nob mice. All bars indicate means + SE. ***P < 0.001.