The initial slope of the fEPSP (mV/ms) was measured within the first two milliseconds of the response immediately after the negative peak of the fiber volley. To standardize responses across experimental conditions, all slope measurements within a given experiment were divided by the average baseline response (10 or 15 min). Then, individual experiments within each condition were averaged across each time point. For statistical analyses, the mean baseline value (last 5 min; fifteen consecutive responses) and the mean experimental value (last 5 min; fifteen consecutive responses) were computed. Statistical comparisons were performed using one-way ANOVAs, repeated measures MANOVAs and student t-tests, p = 0.05 (SPSS).
