Supplementary Figure 1: Features of narrowband high and low gamma power in awake mice.

a) Plot of normalized high gamma power versus visual stimulus size (n = 25 mice, significant effect of size on center-frequency power, p < 0.001, Kruskal-Wallis ANOVA). Error bars are s.e.m. b) As for a) but for increasing visual stimulus contrast and fixed size of 12 degrees (n = 8 mice, significant effect of contrast on center-frequency power, p = 0.002, Kruskal-Wallis ANOVA). c) As for a) but for increasing luminance at 0% contrast (significant effect of luminance on high gamma power, p = 0.003, Kruskal-Wallis ANOVA, n = 4 mice). d) Example power spectra for increasing luminance and 0% contrast. e) Histogram of the center frequency of the narrowband high gamma peak across 25 mice. f) Representative power spectrum in a mouse while running and while still, in the absence of any visual stimulus (grey screen). Line width denotes mean ± s.e.m. g) Plot of the high gamma power between running and still conditions (p < 0.001, n = 22 mice, signed rank test). h) Example power spectra for visually-induced gamma across several stimulus sizes demonstrated a decrease in peak frequency with grating diameter. i) Population data for peak gamma frequency versus stimulus size (p = 0.014, n = 32 mice, significant effect of stimulus size on peak frequency, Kruskal-Wallis ANOVA, error bars are s.e.m).