Why can recalling an established memory make it fragile again?

Details

Memory formation and storage are highly dynamic processes. Understanding memory formation requires clarifying the biological changes that accompany encoding, storage, and retrieval, and how those changes develop over time.

For explicit memories, or memories dependent on the medial temporal lobe, that form after a discrete event and are stored for a long time, the physical changes underlying information encoding and processing—the memory trace, or engram—remain fragile for a time. As time passes, a new memory becomes increasingly resistant to disruption until it is consolidated.

Retrieval or reactivation can make an apparently consolidated memory fragile again; reconsolidation is the process that mediates its restabilization. Reconsolidation also changes with the age of the memory: young memories are sensitive to disruption after reactivation, whereas older memories are more resistant.

Why should retrieval or reactivation make a memory fragile again? In this conceptual discussion, the author proposes that reconsolidation mainly contributes to the ongoing consolidation process and mediates memory strengthening. The author also discusses the literature and results concerning how the passage of time influences memory reconsolidation; the abstract does not describe an original experiment. These points have important implications for using reconsolidation in therapeutic settings.