title: Altered Effective Connectivity of Hippocampus-Dependent Episodic Memory Network in mTBI Survivors.
abstract: Traumatic brain injuries (TBIs) are generally recognized to affect episodic memory. However, less is known regarding how external force altered the way functionally connected brain structures of the episodic memory system interact. To address this issue, we adopted an effective connectivity based analysis, namely, multivariate Granger causality approach, to explore causal interactions within the brain network of interest. Results presented that TBI induced increased bilateral and decreased ipsilateral effective connectivity in the episodic memory network in comparison with that of normal controls. Moreover, the left anterior superior temporal gyrus (aSTG, the concept forming hub), left hippocampus (the personal experience binding hub), and left parahippocampal gyrus (the contextual association hub) were no longer network hubs in TBI survivors, who compensated for hippocampal deficits by relying more on the right hippocampus (underlying perceptual memory) and the right medial frontal gyrus (MeFG) in the anterior prefrontal cortex (PFC). We postulated that the overrecruitment of the right anterior PFC caused dysfunction of the strategic component of episodic memory, which caused deteriorating episodic memory in mTBI survivors. Our findings also suggested that the pattern of brain network changes in TBI survivors presented similar functional consequences to normal aging.
authors.affiliation: Neuroimaging Laboratory, School of Biomedical Engineering, Shenzhen University Health Science Center, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; Departments of Linguistics and Psychology, Xidian University, Xi'an 710071, China.
authors.forename: Hao
authors.identifier: 0000-0002-1854-786X
authors.initials: H
authors.lastname: Yan
authors.affiliation: Departments of Linguistics and Psychology, Xidian University, Xi'an 710071, China.
authors.forename: Yanqin
authors.identifier: 0000-0003-0791-5257
authors.initials: Y
authors.lastname: Feng
authors.affiliation: School of Foreign Languages, Northwestern Polytechnical University, Xi'an 710029, China.
authors.forename: Qian
authors.identifier: 0000-0002-2009-4644
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D000070642:Brain Injuries, Traumatic / Q000473:pathology / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000503:physiopathology; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D061212:Memory, Episodic; D008875:Middle Aged; D009415:Nerve Net / Q000473:pathology / Q000503:physiopathology; D017741:Survivors; D013702:Temporal Lobe / Q000473:pathology / Q000503:physiopathology