Figure 4. 5-HT5A antagonist evokes postsynaptic reduction in M-cell input resistance. A, At top, voltage traces recorded during current injection experiments in control conditions with no prepulse (black), with 50 ms prepulse (red), and with 50 ms prepulse after treatment with SB-699551 (blue). Middle trace shows sound stimulus used for prepulse. Bottom trace shows time course of current injection. B, I/V traces show M-cell depolarization during current injection with no prepulse (black) and 50 ms prepulse (red) in control conditions and no prepulse (blue) and with 50 ms prepulse (green) after SB-699551 treatment. The depicted range shows depolarization from RMP to AP threshold (dashed line). Slope 1 and slope 2 (gray boxes) indicate where linear fits were applied to I/V plots to quantify slope (input resistance). C, Plots of mean ± SEM input resistance for the initial state (slope 1) of M-cell depolarization (control, n = 12, black line; SB-699551, n = 9, blue line) with no prepulse and prepulses at varying ISIs in drug control and SB-699551 treatment conditions. Letters and numbers indicate significant differences (GLMM, post hoc, α = 0.05) between stimulus conditions (numbers) and drug treatment (letters), respectively. D, Plots of mean ± SEM input resistance for the depolarized-state M-cell (control, n = 12, black line; SB-699551, n = 9, blue line) during PPI and drug treatment conditions. Letters and numbers (e.g., A,1, B,2) indicate significant differences (post hoc, α = 0.05) between stimulus (numbers) and treatment (letters) conditions as in C.