Brain–body interactions associated with the transition from mind wandering to awareness of its occurrence

Our thoughts are inherently dynamic and often wander far from our current situation (mind wandering, MW). Although previous research revealed that brain regions involved in arousal regulation modulate neural dynamics to facilitate the transition from MW to the awareness of its occurrence, the specific physiological states and afferent signals underlying this process remain unclear. In this study, we examined electroencephalography, electrocardiography, and respiration data before participants were aware of MW during a task in which they focused on external or internal stimuli (tones or their breath). We showed that the transition to awareness of MW was characterized by decreased alpha and beta activity and a suppression of the parietal later component of the heartbeat-evoked potential (HEP), a modulation pattern identified in this study as a marker of enhanced central processing based on its consistent appearance across internal attention conditions. Furthermore, when participants were instructed to focus on their breath, they were more likely to be in the exhalation phase during the transition to awareness of MW and in the inhalation phase when MW was reported. This respiratory pattern was accompanied by changes in cardiac activity and HEP amplitudes. Based on these findings, we propose that the transition from MW to the awareness of its occurrence is associated with diverse neural activity, including the enhanced processing of bodily signals that co-occurs with specific cardiac and respiratory dynamics.