Figure 3.

The αCaMKII^T286A+/– mutation interferes with new learning mechanisms for fear memory extinction. (A) αCaMKII^T286A+/– mice (n = 19) and wild-type littermates (n = 22) were trained with one CS–US pairing for contextual fear conditioning. Mice were subjected to a single 30-min re-exposure to the conditioning context 24 h after training. Levels of freezing are plotted every 6 min through the 30-min extinction session. Wild-type mice, but not αCaMKII^T286A+/– mutants, exhibited significant reductions in freezing within the 30-min extinction session. (B) In wild-type control mice, levels of contextual freezing were significantly reduced during the last 6-min period compared with the first 6 min of the extinction session, and spontaneous recovery of the extinguished fear memory was observed 21 d later. (*) P < 0.05 vs. the first 6 min and 21 d after extinction. Note that αCaMKII^T286A+/– mutants showed no significant changes in freezing throughout testing and exhibited significantly higher levels of contextual freezing during the last 6 min of extinction as compared with those of wild-type controls ([^#] P < 0.05 vs. wild-type). All data are presented as mean ± SEM.