Mental navigation as a default computational mode in human cognition

The ability to mentally navigate beyond observed experience is a defining feature of human cognition. Converging evidence now indicates that the neural codes supporting physical navigation also underpin goal-directed navigation in nonphysical domains. In this review, I argue that the default mode network (DMN), together with the hippocampal-entorhinal circuitry, constitutes a domain-general system for the organization and mental navigation of relational knowledge. Recent studies demonstrate navigational neural codes not only in the medial temporal lobe, but also across key DMN regions during navigation of both physical and abstract spaces, including social hierarchies, conceptual knowledge, and value-based decision-making. Based on these findings, I propose that the DMN facilitates mental navigation through three interrelated operations, including association, abstraction, and anticipation, that collectively enable the construction and deployment of topologically structured abstract cognitive maps across multiple domains of knowledge. This framework reconciles the diverse functional associations and clinical vulnerabilities of the DMN under a unifying principle: mental navigation as a default computational mode in human cognition.