Human reconsolidation: a reactivation and update.

The reconsolidation hypothesis states that memories, when reactivated, enter a transient, labile state followed by a re-stabilization termed reconsolidation. By affecting the reconsolidation process, memory persistence can be influenced, leading to memory enhancement or decrement. This is a time-dependent process and the result of modulating reconsolidation is present only after the reconsolidation process is completed. Historically, reconsolidation research has been performed on non-human animals, since the methods originally used for reconsolidation disruption are not safe. However, there now exist several techniques safe for humans, and consequently, in recent years, papers on human reconsolidation have emerged. Here, the existing literature on human reconsolidation is reviewed and discussed, including studies on fear memories, appetitive memories, procedural memories, and declarative memories. Methods of memory reactivation are compared between studies, and the consistency and lack of consistency in results over reactivation methods and memory types are discussed. These results provide future challenges, both experimental and clinical, in defining the boundary conditions and mechanisms governing the reconsolidation phenomenon. This article is part of a Special Issue entitled 'Memory Enhancement'.