Consolidated fear memories, when reactivated with a non-reinforced trial, return to a labile state that requires protein synthesis in order to persist. We tested whether the ability of a consolidated trace to undergo reconsolidation is contingent on the reactivation session being an extinction trial. Animals were given 1 tone-footshock pairing per day for 2 days and were tested under extinction conditions on day 3. Rats received injections of either anisomycin (A) or vehicle (V) into the lateral and basal amygdala after each trial resulting in 4 groups; V/V, A/A, A/V, V/A (1st & 2nd letters denote the treatments for 1st & 2nd trials, respectively). Consolidation and Reconsolidation make opposite predictions for group V/A. Consolidation theory predicts the A should only block the acquisition of the new memory on the 2nd trial and have no effect on the trial 1 memory which remains consolidated. Thus, group V/A should show comparable behavior to group A/V. Reconsolidation predicts that the conditioning session should return the memory for the 1st trial to a labile state. Thus, A should block the reconsolidation of the 1st trial memory and the consolidation of the new 2nd trial. This group should be comparable to group A/A, in which the consolidation of both trials has been blocked. On test day 3, group V/A was no different than group A/A, consistent with the predictions of Reconsolidation. Thus, reconsolidation occurs regardless of whether the memory has been reactivated during an extinction or conditioning trial.
Supported by: MH 46516, 38774, 00956, 58911 to JEL and, VW I/77 376 and HSFP RGP0094/2001-B to KN and JEL.