Sex Differences in Hierarchical and Modular Organization of Functional Brain Networks: Insights from Hierarchical Entropy and Modularity Analysis

TL;DR

This study investigates sex differences in the hierarchical and modular organization of brain networks, revealing distinct patterns in connectivity and hierarchy complexity between females and males, with implications for understanding neural mechanisms.

Contribution

It introduces a novel analysis of hierarchical entropy and modularity to compare sex differences in brain network organization, highlighting distinct interaction patterns.

Findings

Females show stronger within-module connectivity.

Males exhibit more complex hierarchical structures.

Negative correlation between hierarchy complexity and modularity.

Abstract

Existing studies have demonstrated significant sex differences in the neural mechanisms of daily life and neuropsychiatric disorders. The hierarchical organization of the functional brain network is a critical feature for assessing these neural mechanisms. But sex differences on the hierarchical organization is not fully investigated. Here, we explore whether hierarchical structure of brain network differs between females and males. At the group level, we measure the hierarchical entropy and the maximum modularity of each individual, and identify a significant negative correlation between the complexity of hierarchy and modularity in brain networks. On average, female brain networks have stronger connectivity within the module, whereas male brain networks demonstrate more complex hierarchy. At the consensus level, we use co-classification matrix to investigate the detailed differences in the hierarchical organization between sexes and observe that females and males exhibit different interaction patterns of brain regions in the dorsal attention network (DAN) and visual network (VIN). Our finding suggests that females and males employ different network topology to achieve brain functions. In addition, the negative correlation between hierarchy and modularity implies a need to balance the complexity in hierarchical organization of the brain network, which shed light on future studies of brain functions.