Reactivation of neural patterns during memory reinstatement supports encoding specificity.

Encoding specificity states that encoding and retrieving items in the same modality benefits memory, compared to encoding and retrieving in different modalities. In neural terms, this can be expressed as memory cues resonating with stored engrams; the more they overlap the better memory performance. We used temporal pattern analysis in MEG in a sensory match/mismatch memory paradigm (i.e., items presented aurally or visually) to track this resonance process. A computational model predicted that reactivation of encoding-related sensory patterns has opposing effects depending on the match or mismatch between memory cue and encoding modality. Behavioral performance was better in the match than the mismatch condition. Neural pattern reinstatement of MEG activity-benefitted memory only in the match condition, but impaired memory in the mismatch condition. These effects were only obtained for aurally but not visually encoded words. The results suggest that reactivation of encoding-related neural patterns underlies encoding specificity.