Sex difference in the neural correlates of volitional eyes closing.

Volitional eyes closing (EC), which shifts brain's information processing modes from the "exteroceptive" to "interoceptive" state, can promote behaviors (such as episodic memory) that exhibit significant sex difference. Although this act is known to reconfigure a large-scale brain network as its neural correlates, sex difference in such network reconfiguration remains unexplored. Here, we compared between genders the EC-effects on functional network, focusing on the intersubject variability in functional connectivity (IVFC), modularity index, local efficiency, and clustering coefficient. While reliable EC-effects were observed in both genders, females demonstrated greater alterations in IVFC and modularity index than males. Moreover, the female-biased effects of EC were supported by a large-scale cortical basis, primarily affecting the default-mode and visual networks. Finally, a positive relationship was discovered between the sex difference of EC-effects and that of brain anatomy. Jointly, our findings suggested that biological sex serves as a potential factor influencing EC's neural correlates, with widespread impacts on cognitive systems and close link to brain anatomy.