Gender-Related and Hemispheric Effects in Cortical Thickness-Based Hemispheric Brain Morphological Network.

Yong-Ho Choi,Je-Yeon Yun,Jong-Min Lee,Min-Ho Lee,Sa-Kwang Song,Bo-Hyun Kim

doi:10.1155/2020/3560259

Abstract

Objective The current study examined gender-related differences in hemispheric asymmetries of graph metrics, calculated from a cortical thickness-based brain structural covariance network named hemispheric morphological network. Methods Using the T1-weighted magnetic resonance imaging scans of 285 participants (150 females, 135 males) retrieved from the Human Connectome Project (HCP), hemispheric morphological networks were constructed per participant. In these hemispheric morphologic networks, the degree of similarity between two different brain regions in terms of the distributed patterns of cortical thickness values (the Jensen–Shannon divergence) was defined as weight of network edge that connects two different brain regions. After the calculation and summation of global and local graph metrics (across the network sparsity levels K = 0.10‐0.36), asymmetry indexes of these graph metrics were derived. Results Hemispheric morphological networks satisfied small-worldness and global efficiency for the network sparsity ranges of K = 0.10–0.36. Between-group comparisons (female versus male) of asymmetry indexes revealed opposite directionality of asymmetries (leftward versus rightward) for global metrics of normalized clustering coefficient, normalized characteristic path length, and global efficiency (all p < 0.05). For the local graph metrics, larger rightward asymmetries of cingulate-superior parietal gyri for nodal efficiency in male compared to female, larger leftward asymmetry of temporal pole for degree centrality in female compared to male, and opposite directionality of interhemispheric asymmetry of rectal gyrus for degree centrality between female (rightward) and male (leftward) were shown (all p < 0.05). Conclusion Patterns of interhemispheric asymmetries for cingulate, superior parietal gyrus, temporal pole, and rectal gyrus are different between male and female for the similarities of the cortical thickness distribution with other brain regions. Accordingly, possible effect of gender-by-hemispheric interaction has to be considered in future studies of brain morphology and brain structural covariance networks.

Highlights

Structural MRI has been used in attempts to construct group brain networks by detecting whole-brain morphological connectivity patterns based on the interregional morphological similarities or “brain structural covariance” across participants [1] or per individual [2]
Zhong et al investigated how topological asymmetries evolve from adolescence to young adulthood and determined that rightward asymmetry in both global and local network efficiencies was consistently observed in adolescents and young adults and that the degree of asymmetry was significantly decreased in young adults [22]
The overall results of this study indicate that brain network analysis using morphological features provides insights into the understanding of hemispheric asymmetry related to gender

Summary

Introduction

Structural MRI (sMRI) has been used in attempts to construct group brain networks by detecting whole-brain morphological connectivity patterns based on the interregional morphological similarities or “brain structural covariance” across participants (interindividual) [1] or per individual (intraindividual) [2]. MRI (fMRI) have been commonly used for constructing the individual brain networks connected by way of the axonal pathways (in DTI) or coupled changes of brain functional activations (in fMRI), respectively [3, 4]. The hemispheric asymmetry of the structural and functional networks has been studied because it could be an important aspect in understanding the organization of the human brain [12,13,14]. Tian et al investigated the difference in the topologies of the hemispheric functional networks in healthy right-handed adults. Zhong et al investigated how topological asymmetries evolve from adolescence to young adulthood and determined that rightward asymmetry in both global and local network efficiencies was consistently observed in adolescents and young adults and that the degree of asymmetry was significantly decreased in young adults [22]

Methods

Results

Conclusion