Figure 3.

EPSP induction has long-lasting, site-specific effects on subsequent oscillatory events. All stimuli were two-site, threshold tetani (con) other than indicated by arrows (see below). (A) Between-site correlations (at 0 ms) for the last 200 ms of post-tetanic oscillation. A two-site tetanus at 2× threshold (arrow, •) generated a marked increase in synchrony at beta frequencies, which was maintained for >90 min (•, n = 4, P < 0.01, two-way ANOVA for the first 30 min). A single-site, 2× threshold tetanus (arrow, ○) produced no effect on the lack of synchrony at the end of the oscillation observed in the control situation (○, n = 5). (B) Between-site correlations (at 0 ms) for the first 200 ms of post-tetanic oscillation. A single-site, 2× threshold tetanus (arrow, ○) produced a lasting (>30 min) decrease in between-site synchrony or an anticorrelation (○, n = 5, P < 0.05, two-way ANOVA for the first 30 min). Two-site, 2× threshold tetani (arrow, •) did not alter synchrony during the gamma oscillation.