Figure 4.

Tuning characteristics to sinusoidal AM stimuli. A, Probability distributions of firing rates (FRs) during each stimulus (colors) and silence (gray area), for RS cells (left) and NS cells (right). For each group, data were fit with a log-normal distribution. NS FRs are higher than RS cells (ANOVA p = 1.31e⁻¹³⁴; overall medians for each group are denoted by black diamonds: RS cells = 2.35 spikes per second, NS cells = 11.08 spikes per second). Within RS cells, 32 and 16 Hz (yellow and dark gray lines) yielded firing rates significantly lower than one irregular stimulus (green line; Kruskal–Wallis p = 0.007, Bonferroni post hoc correction). For NS cells, none of the stimulus FR distributions significantly differed (Kruskal–Wallis, p = 0.073). B, Proportion of RS and NS populations responsive to each periodic AM stimulus as measured by change in average FR. The proportion of units in which FR significantly increased from spontaneous rate is shown by the blue area for each AM rate, and the proportion of units with decreased FR from spontaneous is shown in yellow (significance determined by Wilcoxon rank-sum, p < 0.01, Bonferroni corrected). C, Proportion of RS and NS cells that were significantly synchronized is shown in orange for each AM rate (significance determined by Rayleigh statistic, p < 0.01, Bonferroni corrected).