Impaired STD-LTP is associated with elevated Pr in the cortical inputs to LA in Rap1 KO mice. WT (W) and KO (K) slices. A, STD-LTP protocol. B, LTP in cortical input to LA. Insets represent EPSP before (1) and after (2) induction. Calibration: 10 mV, 10 ms. C, PPR before and after LTP induction in cortical input to LA. **p < 0.01. D, CV of EPSP slopes before and after LTP induction in cortical input to LA. *p < 0.05. E, Plot of CV−2 against percentage LTP in slices from WT mice (r = 0.647; n = 11). F, The progressive blockade of NMDA currents by MK-801 during cortical input stimulation. Each point represents averaged normalized currents from eight WT and seven KO neurons.