Figure 5.

Evidence for reinstatement of CS fear following immediate or delayed extinction in rats. (A) Mean freezing during the post-extinction test (left, Post-Ext. test) and the post-reinstatement test (right, Post-Reinst. test) for all rats in the immediate extinction condition. (B) Mean freezing during the post-extinction test (left, Post-Ext. test) and the post-reinstatement test (right, Post-Reinst. test) for all rats in the delayed extinction condition. Reinstatement of CS fear during the post-reinstatement test was evident regardless of whether extinction occurred 12 min or 3 d following fear acquisition. Note also that summation of CS and context fear does not account for return of CS-elicited fear in the ext.–reinst. group; summation was minimal (compare CS-elicited freezing in the no-ext.–reinst. groups between the post-extinction test and the post-reinstatement test). (Hatched bars) No extinction–reinstatement; (open bars) extinction–no reinstatement; (solid bars) extinction–reinstatement. *P < 0.05 vs. ext.–no-reinst. group, ⁺P < 0.05 vs. no-ext.–reinst. group.