Inhibition of prefrontal protein synthesis following recall does not disrupt memory for trace fear conditioning

Background: The extent of similarity between consolidation and reconsolidation is not yet fully understood. One of the differences noted is that not every brain region involved in consolidation exhibits reconsolidation. In trace fear conditioning, the hippocampus and the medial prefrontal cortex (mPFC) are required for consolidation of long-term memory. We have previously demonstrated that trace fear memory is susceptible to infusion of the protein synthesis inhibitor anisomycin into the hippocampus following recall. In the present study, we examine whether protein synthesis inhibition in the mPFC following recall similarly results in the observation of reconsolidation of trace fear memory. Results: Targeted intra-mPFC infusions of anisomycin or vehicle were performed immediately following recall of trace fear memory at 24 hours, or at 30 days, following training in a one- day or a two-day protocol. The present study demonstrates three key findings: 1) trace fear memory does not undergo protein synthesis dependent reconsolidation in the PFC, regardless of the intensity of the training, and 2) regardless of whether the memory is recent or remote, and 3) intra-mPFC inhibition of protein synthesis immediately following training impaired remote (30 days) memory. Conclusion: These results suggest that not all structures that participate in memory storage are involved in reconsolidation. Alternatively, certain types of memory- related information may reconsolidate, while other components of memory may not.