Challenging the notion of a task-negative network: default mode network involvement under varying levels of cognitive effort
Sarah Weber, André Aleman, Kenneth Hugdahl preprint
The brain's default mode network (DMN), traditionally considered a task-negative network active during rest, and the extrinsic mode network (EMN), active during demanding tasks, both contribute to low-effort cognitive processing. Using fMRI with a Stroop task, participants alternated between rest, low effort (word reading), and high effort (color naming). The DMN was more active during low effort than high effort, showing gradual regulation based on demand. The typical anti-correlation between DMN and EMN occurred only during low effort, not rest or high effort. This challenges the view of the DMN as solely task-negative, suggesting both networks support low-effort cognition, while rest and high effort are dominated by DMN and EMN respectively.