Fig. 2.

Dose-dependent effects of muscimol on afferent vs. intracortical responses in layer 4 demonstrate selective inhibition of latter with optimal dose (100 μM). A: muscimol (100 μM) inhibited spontaneous LFP fluctuations in example traces from predrug and muscimol conditions (top, left and center). Fluctuations were quantified as the SD of the mean LFP for twenty-five 100-ms prestimulus epochs, normalized to predrug values and averaged across animals (histogram, top right; n = 9). A similar analysis at each dose (graph, bottom) showed no effect for ≤50 μM and reduced fluctuations at 100 μM (*; see results). B: effects of muscimol on CF-evoked current sinks are shown in example traces (top) and group data (bottom) and reveal a differential effect at 100 μM on initial (first 5 ms from onset) and peak (20–50 ms from onset) current sinks, each normalized to predrug values. C: effect of muscimol on CF-evoked multiunit activity (MUA). Example of average rectified MUA (left; tone onset at 0 ms) and group data (right; normalized to predrug MUA amplitude) show significant reduction of MUA by 100 μM muscimol.