Figure 8. Dependence of LTP on frequency of PF stimulation.

A, absence of LTP after 60 BSs repetitively applied at 0.25 Hz. Mean ± s.e.m. (n = 4). B, LTP was not induced after 60 BSs applied at 4 Hz, but was rescued in the presence of the CB1 receptor antagonist AM281 (2 μm). Right panel, averaged amplitudes of PF-EPSC during 21–30 min after 4 Hz BS in the absence and presence of AM281. Mean ± s.e.m. (n = 5). C, summary of the BS frequency dependence of LTP. Mean ± s.e.m. (n = 4–5).