Consolidation and reconsolidation share behavioral and neurochemical mechanisms.

Abstract

After encoding, memory traces are fragile and easily disrupted by new learning until they are stabilized through a process termed consolidation1,2. However, several studies have suggested that consolidation does not make memory traces permanently stable. The results of these studies support the theory that the retrieval of previously consolidated memory, termed reactivation, renders the memory traces labile again and subject to disruption by new learning unless they go through a further consolidation process, termed reconsolidation3–8. However, it remains controversial whether reactivation and reconsolidation occur at a human behavioural level9–11 and whether consolidation and reconsolidation have common mechanisms12,13. Here, we found that reconsolidation does occur after reactivation in visual perceptual learning14–25, a type of skill learning, in humans. Moreover, changes in behavioural performance, as well as in concentrations in the excitatory neurotransmitter glutamate and in the inhibitory neurotransmitter GABA (γ-aminobutyric acid), as measured by magnetic resonance spectroscopy, in early visual areas exhibit similar time courses during consolidation and reconsolidation. These results indicate that reconsolidation after reactivation and consolidation in humans share common behavioural and neurochemical mechanisms. Shortly after retrieval, memory undergoes a labile period during which it can be modified. This study shows that this reconsolidation phase shows the same behavioural and neural characteristics as the initial learning phase.