Figure 4.

Block of thalamic firing decelerates EEG slow waves during anesthesia. A, Spike raster plots (top three traces; *bursts) from 3 VB TC neurons and EEG from S1 (bottom trace) show the effects of 50 μm TTX and 300 μm TTA-P2 dialysis in the VB. The predominant burst firing during aCSF is virtually abolished by TTX and TTA-P2, an effect accompanied by slowing of the EEG rhythm. B, Event-triggered averages of raw EEG traces centered on the middle point of DOWN to UP state transitions were calculated after 1 h of aCSF, TTX, and TTA-P2 dialysis (n = 438, 243, and 222 transitions, respectively). C, Normalized (to predrug period), time-dependent decrease of slow waves by TTX (n = 5) and TTA-P2 (n = 5) (drug dialysis starts at 0). D, EEG power spectra 60 min after start of drug dialysis. E, Normalized (to predrug period), time-dependent reduction of spindle waves by TTX and TTA-P2. C–E, Solid lines indicate the mean; color shadings indicate SEM. In this and the following figures, illustrated drug concentrations during microdialysis are those of the inlet dialysis tube (for brain concentration delivered by dialysis probes, see Fig. 3E). In this experiment and those depicted in Figures 5, 6, and 7, the dialysis probes were inserted in a fully vertical position.