Disorganized functional architecture of hippocampal subregional networks in major depressive disorder

Motivation: Different methods of subdividing hippocampus lead to inconsistencies in neuroimaging studies of major depressive disorder (MDD). Currently, data-driven functional connectivity of hippocampal subregions has not been reported in MDD. Goal(s): To determine the most appropriate hippocampal subdivisions and investigate intrinsic connectivity changes in hippocampal networks related to MDD. Approach: We applied a data-driven connectivity-based parcellation to determine optimal hippocampal subdivisions, assess hippocampal functional connectivity, and explore its relationship with clinical symptoms in MDD. Results: The data was best represented by a two-cluster model of rostral and caudal subregions. The rostral hippocampus exhibited enhanced connectivity in MDD patients, which was associated with clinical symptoms. Impact: Our results of connectivity architectures of hippocampal subregions demonstrate the functional segregation of the hippocampus along its long axis and provide insights into the functional connectivity alterations within hippocampal subregions associated with MDD.