The default mode network (DMN), a set of brain regions traditionally linked to off-task or mind-wandering states, actually contributes to detailed, task-relevant cognition during active tasks. Using fMRI, participants performed working-memory tasks while reporting their thoughts. Patterns of neural activity showed that distinctions between on- and off-task thought involved regions near sensory and motor cortex, not the DMN. However, the level of detail in ongoing thought corresponded to activity patterns within the DMN during memory maintenance. These findings indicate the DMN supports detailed cognition under active task conditions, challenging the view that it is solely task-negative.
The default mode network supports cognition independent of immediate environment and higher-order conceptual representations. A novel paradigm manipulated perceptual information availability and representational complexity during decision-making. Brain regions including left and right angular gyri and left middle temporal gyrus responded when cognition combined stimulus independence with multi-modal information. These default mode network sites showed stronger response to demanding memory judgments than easier perceptual tasks, contradicting the view they support automatic cognition. These regions were at the extreme end of a macroscale gradient from sensorimotor to transmodal cortex, suggesting functional distance from sensory input enables conceptually rich cognitive states in absence of input.
When a task is undemanding, people often let their minds wander to personally relevant thoughts. The dorsolateral prefrontal cortex (DLPFC), a brain region known for maintaining goal representations, also helps prioritize off-task thinking. Neural activity in the DLPFC was high both when people were on-task under demanding conditions and off-task during a non-demanding task. Individuals who increased off-task thought when external demands decreased showed weaker correlation between neural signals linked to external tasks and lateral default mode network regions within the DLPFC, and had less cortical grey matter in regions sensitive to those external signals. The findings suggest that humans use the DLPFC to align cognition with personal goals when environmental demands drop, prioritizing daydreaming.
Mind-wandering involves cognition detached from the immediate environment. The default mode network (DMN), a set of brain regions far from sensory and motor areas, is implicated but its exact role is unclear. This study examined how individual differences in resting-state DMN connectivity relate to performance on memory, social, and planning tasks and to variability in spontaneous thought. Poor external engagement was linked to stronger coupling between medial and dorsal DMN subsystems, while decoupling of the core from the cerebellum predicted detailed memory retrieval. Both patterns predicted off-task future thoughts. The DMN supports stimulus-independent cognition through strong subsystem coupling and allows memory representations to form conscious experience.