The default mode network, typically linked to internally-directed thoughts like mind wandering, shows reduced activity during many cognitive tasks. However, this network can become more active during a large and demanding switch in task set. Using multivoxel pattern analysis, the authors found that regions within the default mode network encode task-relevant information during task performance. Activity in this network may be driven by major revisions of cognitive context, whether internally or externally focused.
The default mode network (DMN) is typically thought to support internally focused thought, but a new brain imaging study shows it also activates during certain external task switches. Using fMRI, 24 participants performed a task-switching experiment. The DMN increased activity not only during task switches, replicating prior findings, but also during brief rests and task restarts after rest. These results challenge theories that restrict DMN function to internal or self-directed cognition. The authors propose 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.
Core Default Mode Network (DMN) activity increases during switches between externally-focused tasks, but this response depends on how tasks are grouped by the order they were learned, not on the number of tasks. In an fMRI study, participants performed tasks while the number of relevant tasks varied, but DMN activation at switches was unaffected by task count. Instead, multivariate decoding showed the Core DMN hierarchically represents individual tasks, task domains, and higher-order groupings based on instruction order. The findings suggest that as instruction complexity increases, rules are organized into higher-level chunks, and Core DMN activity peaks at switches between those chunks.