Memory consolidation is a category of processes that stabilize a memory trace after its initial acquisition. Consolidation is distinguished into two specific processes, synaptic consolidation, which is synonymous with late-phase long-term potentiation and occurs within the first few hours after learning, and systems consolidation, where hippocampus-dependent memories become independent of the hippocampus over a period of weeks to years. Recently, a third process has become the focus of research, reconsolidation, in which previously-consolidated memories can be made labile again through reactivation of the memory trace.
Memory consolidation was first referred to in the writings of the renowned Roman teacher of rhetoric Quintillian. He noted the “curious fact… that the interval of a single night will greatly increase the strength of the memory,” and presented the possibility that “… the power of recollection … undergoes a process of ripening and maturing during the time which intervenes.” The process of consolidation was later proposed based on clinical data illustrated in 1882 by Ribot’s Law of Regression, “progressive destruction advances progressively from the unstable to the stable”. This idea was elaborated on by William H. Burnham a few years later in a paper on amnesia integrating findings from experimental psychology and neurology. Coining of the term “consolidation” is credited to the German researchers Müller and Alfons Pilzecker who rediscovered the concept that memory takes time to fixate or undergo “Konsolidierung” in their studies conducted between 1892 and 1900. The two proposed the perseveration-consolidation hypothesis after they found that new information learned could disrupt information previously learnt if not enough time had passed to allow the old information to be consolidated. This led to the suggestion that new memories are fragile in nature but as time passes they become solidified