Hemispheric asymmetries in resting-state connectivity: insights from healthy controls and implications for neurological disorders

The human brain exhibits intricate hemispheric asymmetries at both structural and functional levels. Recent research highlights the significance of these asymmetries in various neurological diseases, with left-sided pathologies often associated with worse clinical outcomes. This study aims to unravel the lateralisation of resting-state network connectivity in the human brain using rs-fMRI, exploring its implications for the pathophysiology of neurological disorders. In this study, we utilized a multifaceted analytical approach with seven graph-theoretical measures, three voxel-based metrics, and the laterality index. The study was conducted on two independent datasets: a Local cohort comprising 102 right-handed healthy control participants, and a comparative cohort of 86 right-handed healthy control participants from the ADNI database.Our results reveal significant lateralisation of resting-state functional network connectivity in several brain regions across both datasets. The following regions exhibited consistent significant left-sided lateralisation in both cohorts, even when using different metrics: Cerebellum (10, Crus2, 6), Frontal (Orbital, Inferior Triangular, Superior), Supramarginal (posterior), Lateral Occipital, Inferior Temporal (posterior). Right lateralisation: Cerebellum 7b, Frontal Pole, Supracalcarine, Juxtapositional Lobule. The consistency of lateralisation patterns across multiple analytical methods and independent cohorts underscores the importance of our findings. The observed lateralisation phenomena might have important implications for the pathophysiology of various neurological diseases, potentially offering insights into disease progression and prognosis.