KAR antagonism lowers the threshold for induction of theta-burst LTP. A, Graph of pooled data to determine the threshold for induction of theta-burst LTP of fEPSPs recorded in naive slices. TBS paradigm consisted of four-pulse bursts at 50 Hz repeated either two (black; n = 9), three (dark gray; n = 5), or five times (light gray; n = 5) at a theta frequency of 5 Hz, as illustrated. B, Graph of pooled data comparing the effects of a subthreshold TBS (4 shocks at 50 Hz repeated twice at 5 Hz) under control conditions (n = 9) in the presence of 200 nm ACET (n = 8) and 10 μm LY382884 (n = 6) in naive slices. In this and Figure 2, pooled data are accompanied by traces from a single representative example from time points indicated.