Enhanced individual difference of functional brain network induced by volitional eyes closing.

Volitional eyes closing (EC) can promote the interoceptive thoughts that vary considerably among individuals. Although this behavior is known to recruit a large-scale brain network as its neural underpinning, individual variability in such network recruitment remains unexplored. Here, we compared the intersubject variability in functional connectivity (IVFC) between the EC and eyes opening conditions. It was found that the IVFC significantly increased during the EC condition, which could be replicated in different public datasets and multi-resolution parcellations. Moreover, the EC-enhanced IVFC focused on selective subsets of FCs, with predominant impact on the default-mode, dorsal attention, and visual networks. Finally, a positive relationship was discovered between EC-enhanced IVFC and deep involvement in the task-unrelated thoughts that was measured with an additional dataset. Collectively, these results suggested that enhanced individual difference characterize the functional network of volitional EC, with widespread impact on cognitive systems and potential connection to task-unrelated thoughts.