A More Female-Characterized Resting-State Brain: Graph Similarity Analyses of Sex Influence on the Human Brain Intrinsic Functional Network.

It remains unclear whether human species exhibits sexual dimorphism in brain activities, and how the dimorphisms associated with sex-characterized behaviors. Here, in a large dataset from Human Connectome Project, we investigated sex differences of resting-state network structure by using local and global network graph similarity analysis. The "typical male" and "typical female" resting-state networks were highly similar. However, we found significant inter-sex difference in all local brain networks compared with sex-label permutations. The global and many local network topologies showed significant higher intra-female similarity, while males' network topologies were more dissimilar to each other. Additionally, by using global graph similarity analysis, we found that female individuals whose brain network were more similar to the average pattern present lower social-related anger, lower social distress and better companionships, while similar effects were not detected for males. Our study confirms the existence of sex-related resting-state network topology. Female's intrinsic brain is closer to a typical pattern than male's, and they may more fulfill the "similarity breeds connection" principle in building social ties.