(A) Stimulus-induced change in slow (top row) and fast (bottom row) gamma power for three spatial frequencies (1, 2, and 4 cpd) and four orientations (0°, 45°, 90°, and 135°). Gray dots represent data for each of the 227 healthy subjects. SEM is indicated as black vertical lines on the bars. Because of a large variability in gamma power across subjects, the SEMs are barely visible. Therefore, for clarity, we have plotted these means and SEM (error bars) separately in the insets. We statistically quantified differences in these means across orientations using one-way ANOVA at each spatial frequency. We found that these were not significant for any gamma at any spatial frequency, except for slow gamma at 2 cpd (for slow gamma, 1/2/4 cpd: F(3,904) = 0.63/5.81/1.37, p=0.59/0.0006/0.25; for fast gamma, 1/2/4 cpd: F(3,904) = 0.27/0.96/0.83, p=0.84/0.41/0.48). Specifically, for 2 cpd, change in slow gamma power was 0.92 ± 0.06, 1.31 ± 0.07, 1.01 ± 0.08, and 1.21 ± 0.08 dB (mean ± SEM) for 0°, 45°, 90°, and 135° orientations, respectively, as seen in the insets. (B) Scatter plots showing orientation selectivity for slow gamma (on ordinate) and fast gamma (on abscissa) for 227 healthy subjects at 1, 2, and 4 cpd (top, middle, and bottom rows). Mean ± SEM orientation selectivity for slow and fast gamma are mentioned in the plots in pink and orange, respectively. Mean orientation selectivity is also indicated as a red cross in the plots.