Synaptic protein degradation as a mechanism in memory reorganization.

An accumulating body of evidence shows that reactivated long-term memory undergoes a dynamic process called reconsolidation, in which de novo protein synthesis is required to maintain the memory. These findings open up a new dimension in the field of memory research. However, few studies have shown how once-consolidated memory becomes labile. The authors' recent findings have demonstrated that pre-existing long-term memory becomes unstable via the ubiquitin/ proteasome-dependent protein degradation pathway and that this labile state is required for the reorganization of fear memory. Here, the authors review this finding and focus on the labile state that is critical for the reorganization of memory triggered after memory retrieval.