Consolidation and reconsolidation share behavioural and neurochemical mechanisms

After encoding, memory traces are fragile and easily disrupted by new learning until they are stabilized through a process termed consolidation(1,2). 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 reconsolidation(3-8). However, it remains controversial whether reactivation and reconsolidation occur at a human behavioural level(9-11) and whether consolidation and reconsolidation have common mechanisms(12,13). Here, we found that reconsolidation does occur after reactivation in visual perceptual learning(14-25), 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 (gamma-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.