Figure 6. Intra-CA1 injection of cholinergic antagonists blocks learning-enhanced synaptic plasticity.

(a) Experimental design of unilateral drug infusion into CA1 region and subsequent behavioural test and electrophysiological assay. (b) Uilateral intra-CA1 injection of Sco, Prz or Mla did not impair learning. One-way factorial ANOVA. (c) Unilateral intra-CA1 injection of Sco or muscarinic M₁ receptor antagonist (Prz) blocked the learning-dependent increase in the amplitude and frequency of the mEPSC but not of the mIPSC. In contrast, unilateral intra-CA1 injection of a nicotinic α7 receptor antagonist (Mla) blocked the learning-dependent increase in mIPSC amplitude. **P<0.01 versus untrained (untrained: n=43, Sal+IA trained: n=22 Sco+IA trained: n=25, Prz+IA trained: n=49, Mla+IA trained: n=48, one-way factorial ANOVA followed by post hoc analysis with the Fisher’s PLSD test). These data are collected from the injected henisphere. Control experiments without drugs were collected from saline-injected animals. (d) Experimental design of bilateral drug infusion into CA1 region and subsequent behavioural test. (e) Bilateral intra-CA1 injection of Sco, Prz or Mla impaired learning. **P<0.01 versus saline (Sal: n=6, Sco: n=5, Prz: n=8, Mla: n=5, one-way factorial ANOVA followed by post hoc analysis with the Fisher’s PLSD test). The number of cells (c) or animals (b,e) is shown at the bottom of the bars. Error bars indicate ±s.e.m.