Made together, replayed together: Memory consolidation during sleep involves context reinstatement in humans

Abstract

New memories arent quarantined from each other when first encoded; rather, they are interlinked with memories that were encoded in temporal proximity or share semantic features. By selectively biasing memory processing during sleep, here we test whether context influences sleep-consolidation. Participants first formed 18 idiosyncratic narratives, each linking four objects together. Before sleep,they also memorized an on-screen position for each object. During sleep, 12 object-specific sounds were unobtrusively presented, thereby cuing the corresponding spatial memories and impacting spatial recall as a function of initial memory strength. As hypothesized, we find that recall for non-cued objects contextually linked with cued objects also changed. Post-cue electrophysiological responses suggest that activity in the sigma band supports context reinstatement and predicts context-related memory benefits. Concurrently, context-specific electrophysiological activity patterns emerge during sleep. We conclude that reactivation of individual memories during sleep evokes reinstatement of their context, thereby impacting consolidation of associated knowledge.