Rites of passage of the engram: reconsolidation and the lingering consolidation hypothesis.

Memory consolidation refers to the progressive stabilization of items in long-term memory as well as to the memory phase(s) during which this stabilization takes place. The textbook account is that, for each item in memory, consolidation starts and ends just once. In recent years, however, the notion that memories reconsolidate upon their reactivation and hence regain sensitivity to amnestic agents has been revitalized. This issue is of marked theoretical and clinical interest. Here we review the recent literature on reconsolidation and infer, on the basis of the majority of the data, that blockade of reconsolidation does not induce permanent amnesia. Further, in several systems, reconsolidation occurs only in relatively fresh memories. We propose a framework model, which interprets reconsolidation as a manifestation of lingering consolidation, rather than recapitulation of a process that had already come to a closure. This model reflects on the nature of consolidation in general and makes predictions that could guide further research.