Conditional Mef2c knockouts have unimpaired long term potentiation. (A) LTP in the hippocampus induced by theta burst was normal in conditional Mef2c KO mice in comparison to control mice. (B) Input-output curves were measured in hippocampal slices from CTL and Mef2c KO mice. Field potential slopes were plotted as a function of presynaptic volley at 0.01, 0.025, 0.075, 0.125 mV stimulation intensities. (C) Paired pulse ratio of the first 2 responses elicited by various stimulation frequencies at Schaeffer collateral synapses. Mef2c KO mice exhibited significantly augmented PPF at Interstimulus intervals of 20 ms (t(22) = 1.9, p < 0.05), 30 ms (t(22) = 2.1, p < 0.05) and 50 ms (t(22) = 2.9, p < 0.05), indicating decreased probability of neurotransmitter release (CTL, n=11; KO, n=13 for all the experiments)(*p < 0.05).