Fig. 6.

LTP is unimpaired by cannabinoid receptor activation when the postsynaptic membrane is depolarized during tetanus. a, Bottom, Summary of control and 1 μm WIN55,212-2 whole-cell experiments. Data are expressed as normalized EPSC amplitudes (± SEM). The amplitudes of EPSCs were normalized to the baseline value preceding the induction of LTP. Testing stimuli were given every 20 sec. Mean values of LTP 25–35 min after tetanus when the postsynaptic cell was depolarized to −20 mV were 1.56 ± 0.11 for controls (n = 8;gray circles) and 1.62 ± 0.27 in the presence of 1 μm WIN55,212-2 (n = 7; black squares). Top, Sample tracesshowing EPSCs recorded in the presence of WIN55,212-2 before (left) and after (right) the induction of LTP. b, Cumulative probability histogram of the magnitude of whole-cell LTP 25–35 min after tetanus. Cumulative probability distributions are shown for control EPSCs (solid gray), EPSCs recorded in the presence of 1 μmWIN55,212-2 (solid black), and EPSCs recorded in the presence of 50 μm AP-5 (dotted black). The control and 1 μm WIN55,212-2 distributions were not significantly different (Kolmogorov–Smirnov two-sample test,p > 0.05).