FIG. 6.
Peristimulus background activity has an influence on the amplitude of evoked slow waves. A: triggered single-trial responses in the left frontal derivation after the right frontal derivation was stimulated (200 trials from one representative rat) sorted as a function of the latency to the preceding spontaneous high-amplitude slow wave (> mean +1 SD). Voltage is color-coded (red, positive; blue, negative). Note that the proximity of the preceding spontaneous slow wave to the trigger resulted in a failure of the electrical pulse to trigger slow waves in ∼40 cases. B: typical individual traces depicting slow waves triggered on the background of low-amplitude activity (top trace) and triggered immediately after spontaneous slow wave (bottom trace) from 1 representative animal. Positivity - upward. Vertical bar denotes the timing of the trigger. C and D: mean amplitude of spontaneous slow waves, preceding the trigger, and their latency prior to the trigger, were computed separately for those cases where full-fledged high-amplitude evoked slow waves was induced, and for those cases where the induction was not successful. Specifically, for this analysis all individual trials were sorted based on the maximal value of the signal within the 1st 250 ms after the trigger. Subsequently, the mean amplitude and the latency of the closest immediately preceding spontaneous slow wave were computed for the top and bottom 100 trials, corresponding to the “biggest” and “smallest” 100 evoked slow waves (mean ± SE, n = 6; *, P < 0.05, paired t-test).