The ‘task’ of mind-wandering splits both multiple demand and default mode regions and ramps-up the deactivating regions

The activation of multiple demand (MD) regions to diverse tasks has been linked to the demands of making task-related cognitive control changes – keeping it focussed on task, controlling attention and working memory, organizing and maintaining a task model that will control the sequence and identity of what is to be done when, etc. Demanding tasks that require such control are also accompanied by a deliberative cognition whereby cognitive changes do not occur automatically and have to be made deliberately. We investigated whether the deliberativeness of cognition activates MD regions regardless of task-related demands. When not engaged in demanding tasks, the mind wanders. We asked participants to do the same during task periods, and to differentiate from rests, we asked them to deliberately and intensely wander their minds across random thoughts. We found that a set of MD regions – pre-supplementary motor area (preSMA), anterior insula, and posterior part of the middle frontal gyrus – activated during these periods, and another set – intraparietal sulcus, right anterior prefrontal cortex – deactivated. In fact, some of the activating regions (e.g., preSMA) activated more during this task than in response to robust working memory updating demands. Dissociations were also present in the Default Mode Network (DMN). Parts of the temporoparietal junction deactivated while posterior cingulate and medial prefrontal regions activated. Lastly, we found that the deactivating regions ramped-up their activity across the ‘task’ duration, showing that this ramp-up, previously linked to demands of sequentially organizing extended tasks, occurs during any construed task, including those without such demands.