Population data showing the effect of carbachol on corticothalamic responses. A, Population corticothalamic responses (n = 8) evoked by each of the 10 stimuli in trains at 2, 5, 10, 20, and 40 Hz during control conditions and during carbachol. Responses were measured by summing the spikes evoked during a 20 ms time window after each thalamic radiation stimulus. Also displayed is the mean ± SD level of spontaneous firing during the different conditions, as spikes per 20 ms and as spikes per second (in Hertz). B, Population PSTHs (n = 8) of corticothalamic responses at 0.1, 2, 5, 10, 20, and 40 Hz during control conditions and during application of carbachol in the thalamus. The PSTHs correspond to the 10th stimulus in the train.