The default mode network: where spontaneous thought meets memory consolidation.

The default mode network (DMN), a set of brain regions active during wakeful rest, supports spontaneous thoughts and memory reactivation. Emerging evidence suggests that DMN activity during spontaneous thought provides a neural context that helps propagate recently learned information to aid long-term memory consolidation. The review highlights links between spontaneous thought and improved memory performance, describes how DMN subsystems coordinate with the hippocampus during reactivation, and connects spontaneous thought content to memory reactivations. Future directions are outlined to clarify the mechanistic role of spontaneous thought in memory consolidation through interactions between the DMN, hippocampus, and broader cortical networks.

Study at a glance

Abstract

The default mode network (DMN) is a distributed set of brain regions engaged during wakeful rest. Spontaneous thoughts - internally directed mental experiences that arise with relative freedom and few constraints on their content or transitions - are ubiquitous during wakeful rest. Spontaneous memory reactivation - neural events in which recently learned information is reinstated - also occurs at rest and has a fundamental role in long-term memory consolidation. Here, we synthesize emerging behavioral, theoretical, and neurophysiological evidence suggesting that DMN activity associated with spontaneous thought provides a neural context that promotes the propagation of reactivated information to aid consolidation. We highlight findings linking spontaneous thought to improved memory performance, discuss how specific DMN subsystems coordinate with the hippocampus during reactivation, and highlight recent studies that connect spontaneous thought content to memory reactivations. We conclude by outlining future directions to clarify the mechanistic role of spontaneous thought in memory consolidation mediated by the complex interplay between the DMN, hippocampus, and broader cortical networks.