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INTRA-AMYGDALA ANISOMYCIN BLOCKS THE RECONSOLIDATION OF BRIEFLY REACTIVATED OR EXTINGUISHED AUDITORY FEAR MEMORIES.

J.E.LeDoux¹; S.Duvarci¹; K.Nader^2*

1. Ctr. for Neural Sci., NYU, NY, NY, USA

2. Psychology, McGill Univ., Montreal, PQ, Canada

We have previously demonstrated that inhibition of protein synthesis with anisomycin after the reactivation of a consolidated auditory fear memory caused amnesia on subsequent long term tests. This and other findings suggested that we had blocked the reconsolidation of that memory(Nader et al., 2000). In contrast, post-reactivation anisomycin infusions have also been demonstrated to promote performance by blocking the consolidation of extinction in a conditioned taste aversion paradigm (Berman & Dudai, 2001). One discrepancy that could explain the differential results is that reactivation was sufficient to induce extinction only in the study that demonstrated blockade of extinction consolidation and not in the study that blocked reconsolidation. Thus, it is possible that molecular competition exists between these two separate memory processes, such that the dominant memory process after reactivation will be the one affected by protein synthesis inhibition (Nader, 2003). To evaluate this possibility, we used a within-group fully counterbalanced design in which each rat was trained with two different tones. 24 hr after the end of training, one CS was briefly reactivated for 30 s, and then presented with a 600 s presentation of the other CS (which leads to extensive extinction of freezing). Following the reactivation and extinction of the CSs rats were infused with either anisomycin or vehicle into the lateral-basal amygdala. The next day rats were tested for their post-reactivation long-term memories for the two CSs. The results showed that protein synthesis inhibition blocked the reconsolidation of the reactivated tone and decreased the freezing of the extinguished tone further. Thus, the most parsimonious explanation of the findings is that the dominant memory process in the amygdala is reconsolidation.
Support Contributed By: HFS, VW, to KN and JEL and NIMH to JEL

Citation:
J.E. LeDoux, S. Duvarci, K. Nader. INTRA-AMYGDALA ANISOMYCIN BLOCKS THE RECONSOLIDATION OF BRIEFLY REACTIVATED OR EXTINGUISHED AUDITORY FEAR MEMORIES. Program No. 623.11. 2003 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2003. Online.