Memory consolidation during rest forms shortcuts in a cognitive map

Abstract

Rest and sleep not only strengthen existing memories but also reorganise memories to generate new knowledge that extends beyond direct experience. It remains unclear how this reorganisation affects behaviour. Here, to investigate the behavioural consequences of reorganising memories, we designed a novel protocol to promote memory consolidation during rest using awake, contextual targeted memory reactivation (TMR). We found that promoting memory consolidation during rest improves the ability to make novel inferences by forming 'shortcuts' between memories which have not been experienced together. These shortcuts in memory extend beyond direct experience to facilitate inference. However, these shortcuts impair our ability to flexibly update memories in response to changes in the environment. These findings demonstrate how memories are reorganised during awake rest to construct a cognitive map of our environment that sets a trade-off between efficient and flexible behaviour.