Uncovering the embodied dimension of the wandering mind

When at rest, the mind becomes preoccupied with self-generated thoughts, commonly known as mind-wandering. While the social, autobiographical, and temporal features of these thoughts have been extensively studied, little is known about how frequently the wandering mind turns towards the interoceptive and somatic body. To map this under-explored component of "body-wandering," we conducted a large-scale neuroimaging study in 536 healthy participants, expanding a retrospective multidimensional experience sampling approach to include probes targeting visceral and somatomotor thoughts. Our findings reveal a robust inter-individual dimension of body-wandering characterized by negative affect, high autonomic arousal, and a reduction in socially oriented thoughts. Despite this negative tone, individual differences in the propensity for body-wandering were associated with lower self-reported symptoms of ADHD and depression. Multivariate functional connectivity analyses further revealed that affective, body-oriented thoughts are related to a pattern of thalamocortical connectivity interlinking somatomotor and interoceptive-allostatic cortical networks. Collectively, these results demonstrate that self-generated thoughts exhibit core embodied features which are linked to the ongoing physical and emotional milieu of the visceral body. Significance statementNeuroimaging studies often treat the resting state as a purely cognitive baseline, overlooking the participants embodied experience within the scanner. Here we show that individuals robustly vary in their degree of body-wandering, such that a more somatically focused stream of thought is associated with negative affect, higher arousal, and increased thalamocortical-somatomotor connectivity. Paradoxically, while this state is experienced negatively in the moment, the propensity for embodied mind-wandering correlates with reduced trait level symptoms of depression and ADHD. Collectively, these findings indicate that we must account for the embodied nature of the resting mind to fully understand the neural and clinical mechanisms of self-generated thought.