Fear extinction increases CP-AMPARs in IL synapses. A, Examples of EPSCs recorded at −60 mV and +60 mV in neurons from each group. Data are from the same neurons as in Figure 1. Vertical line indicates when AMPA EPSCs were measured. B, Average AMPAR rectification index of EPSCs from Naive (n = 24 neurons), Con (n = 22 neurons), and Ext (n = 24 neurons) groups. C, The average AMPAR rectification index for each rat (Ext, blue circles; Cond, black circles) showed a significant negative correlation with the percentage freezing at test. D, The AMPA to NMDA ratio for each neuron showed a significant positive correlation with the AMPAR rectification index. E, Behavior of rats used to test percentage blockade by Naspm. F, Time course showing that Naspm (red bar) reduced the AMPAR EPSCs recorded at −60 mV in the Ext, Naive, and Cond groups. G, Group data showing percentage blockade of AMPAR EPSCs by Naspm (50 μm) in Ext (n = 10), Cond (n = 7), and Naive (n = 11) groups. *p < 0.05.