Figure 2.

Induction of LTP reduced the NMDAR-mediated component of synaptic responses but did not affect paired-pulse ratios. A, APV infused continuously before the delivery of HFS blocked induction of LTP. B, Effects of APV when infused after HFS and the induction of LTP. C, Baseline measurements and magnitude of LTP were recorded in slices perfused with ACSF containing 2 mm Ca²⁺ and 2 mm Mg²⁺; HFS delivered at the end of 5 min infusion of 5 mm Ca²⁺ and 0 mm Mg²⁺ (black bar) produced potentiation that remained in place when lower calcium conditions were restored. D, Five minutes of high calcium increased the EPSC amplitude (amp) and reliably reduced the PPR (**p < 0.01). Applied at the end of high-calcium infusion, HFS further increased the EPSC amplitude (amp) without measurably affecting the PPR (n.s. denotes p > 0.60 vs baseline). Plots show means ± SEM for 5–7 slices/group.