Transcranial direct current stimulation of the medial prefrontal cortex dampens mind-wandering in men

Elena Bertossi,Alessio Avenanti,Elisa Ciaramelli,Ludovica Peccenini,Andrea Solmi

doi:10.1038/s41598-017-17267-4

Abstract

Mind-wandering, the mind’s capacity to stray from external events and generate task-unrelated thought, has been associated with activity in the brain default network. To date, little is understood about the contribution of individual nodes of this network to mind-wandering. Here, we investigated the role of medial prefrontal cortex (mPFC) in mind-wandering, by perturbing this region with transcranial direct current stimulation (tDCS). Young healthy participants performed a choice reaction time task both before and after receiving cathodal tDCS over mPFC, and had their thoughts periodically sampled. We found that tDCS over mPFC - but not occipital or sham tDCS - decreased the propensity to mind-wander. The tDCS-induced reduction in mind-wandering occurred in men, but not in women, and was accompanied by a change in the content of task-unrelated though, which became more related to other people (as opposed to the self) following tDCS. These findings indicate that mPFC is crucial for mind-wandering, possibly by helping construction of self-relevant scenarios capable to divert attention inward, away from perceptual reality. Gender-related differences in tDCS-induced changes suggest that mPFC controls mind-wandering differently in men and women, which may depend on differences in the structural and functional organization of distributed brain networks governing mind-wandering, including mPFC.

Highlights

Mind-wandering occurs when attention shifts away from an ongoing task or events in the external environment towards self-generated thoughts unrelated to perceptual reality, and centered instead on current concerns, memories, and future experiences[1]
In the current experiment we investigated the role of medial prefrontal cortex (mPFC) in mind-wandering, by comparing the propensity to mind-wander of young healthy individuals before and after receiving 2 mA cathodal monopolar transcranial direct current stimulation (tDCS) over mPFC, a control site in the occipital cortex, or sham tDCS
We found that tDCS over mPFC reduced the tendency to mind-wander significantly compared to tDCS over the occipital cortex or sham tDCS, but only in men; it had no such effect in women

Summary

Introduction

Mind-wandering occurs when attention shifts away from an ongoing task or events in the external environment towards self-generated thoughts unrelated to perceptual reality, and centered instead on current concerns, memories, and future experiences[1]. Activity in the default network has been linked to the production of mental contents that generally populate mind-wandering episodes, such as remembered or simulated experiences involving the self and others[1,13,14,15]. Kajimura and Nomura administered tDCS (at 1.5 mA for 20 min) with the cathodal electrode over left dlPFC (i.e., over the AF7 electrode) and the anodal electrode over right parietal regions (i.e., over the P4 electrode)[20] This stimulation decreased the propensity to mind-wander relative to the reverse montage (cathodal-parietal/anodal-frontal)[20]. Together, these studies indicate that left dlPFC plays a crucial role in mind-wandering. The use of a cephalic reference over the right hemisphere may have caused a possible contribution of interhemispheric imbalance to the observed behavioral effects

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Conclusion