Role of the default mode network in cognitive transitions

Abstract

A frequently repeated finding is that the default mode network (DMN) shows activa-tion decreases during externally-focused tasks. This finding has led to an emphasis in DMN research on internally-focused self-relevant thought processes. A recent study, in contrast, implicates the DMN in substantial externally-focused task switch-es. Using functional magnetic resonance imaging, we scanned 24 participants per-forming a task switch experiment. Whilst replicating previous DMN task switch ef-fects, we also found large DMN increases for brief rests as well as task restarts after rest. Our findings are difficult to explain using theories strictly linked to internal or self-directed cognition. In line with principal results from the literature, we suggest that the DMN encodes scene, episode or context, by integrating spatial, self-referential and temporal information. Context representations are strong at rest, but re-reference to context also occurs at major cognitive transitions.