Ventromedial prefrontal damage reduces mind-wandering and biases its temporal focus

Abstract

Mind-wandering, an ubiquitous expression of humans' mental life, reflects a drift of attention away from the current task towards self-generated thoughts, and has been associated with activity in the brain default network. To date, however, little is understood about the contribution of individual nodes of this network to mind-wandering. Here, we investigated whether the ventromedial prefrontal cortex (vmPFC) is critically involved in mind-wandering, by studying the propensity to mind-wander in patients with lesion to the vmPFC (vmPFC patients), control patients with lesions not involving the vmPFC, and healthy individuals. Participants performed three tasks varying in cognitive demands while their thoughts were periodically sampled, and a self-report scale of daydreaming in daily life. vmPFC patients exhibited reduced mind-wandering rates across tasks, and claimed less frequent daydreaming, than both healthy and brain-damaged controls. vmPFC damage reduced off-task thoughts related to the future, while it promoted those about the present. These results indicate that vmPFC critically supports mind-wandering, possibly by helping to construct future-related scenarios and thoughts that have the potential to draw attention inward, away from the ongoing tasks.

Keywords: default mode network; mental time travel; mind-wandering; ventromedial prefrontal cortex.

Fig. 1.

Extent and overlap of brain lesions. The figure represents vmPFC patients’ lesions projected on the same seven axial slices of the standard Montreal Neurological Institute brain. The white horizontal lines on the sagittal view are the positions of the axial slices, and the white numbers under the axial views are the z-coordinates of each slice. The color bar indicates the number of overlapping lesions. Maximal overlap occurs in BA 10, 11 and 32. The left hemisphere is on the left side.

Fig. 2.

Mean mind-wandering ratings by participant group and ongoing task. Bars represent SEM. * P < 0.05.

Fig. 3.

Mean proportion of thoughts for each content category out of the total number of off-task thoughts claimed (collapsed across tasks) by participant group. Bars represent SEM. * P ≤ 0.05.

Fig. 4.

Daydreaming and night dreaming frequency scores from the IPI by participant group. Bars represent SEM.* P < 0.05.