title: Unidirectionally affected causal connectivity of cortico-limbic-cerebellar circuit by structural deficits in drug-naive major depressive disorder.
abstract: BACKGROUND
  Structural deficits and resting-state functional connectivity (FC) alterations in the cortico-limbic-cerebellar circuit have been implicated in the neurobiology of major depressive disorder (MDD). This study was conducted to examine the causal connectivity biased by structural deficits in MDD patients.
  
  
  METHODS
  Resting-state functional magnetic resonance imaging data were acquired from 44 drug-naive MDD patients and 44 healthy controls. Granger causality analysis (GCA) was used to analyze the functional data.
  
  
  RESULTS
  We previously observed two brain regions, the left angular gyrus (AG) and the right inferior temporal gyrus (ITG), with reduced gray matter volume (GMV), which were selected as seeds. Compared with healthy controls, the patients showed inhibitory effect from the left AG to the left superior temporal gyrus (STG) and the left inferior frontal gyrus (IFG, opercular part), and from the right ITG to bilateral cerebellum 6. In contrast, the right ITG exhibited excitatory effect to the right insula. However, no abnormal feedback effect was observed in patients. There was no significant correlation between abnormal causal effect and clinical variables, such as HRSD scores, illness duration, and episode number.
  
  
  CONCLUSIONS
  Brain regions within the cortico-limbic-cerebellar circuit showed unidirectionally affected causal connectivities driven by structural deficits in MDD. The findings suggest that the causal topology of the cortico-limbic-cerebellar circuit may be disrupted unidirectionally by structural deficits in MDD.
authors.affiliation: Mental Health Center, the First Affiliated Hospital, Guangxi Medical University, Guangxi, Nanning 530021, China. Electronic address: guowenbin76@163.com.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Guo
authors.affiliation: Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Sichuan, Chengdu, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.affiliation: Mental Health Center, the First Affiliated Hospital, Guangxi Medical University, Guangxi, Nanning 530021, China.
authors.forename: Zhikun
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Mental Health Center, the First Affiliated Hospital, Guangxi Medical University, Guangxi, Nanning 530021, China.
authors.forename: Jianrong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Mental Health Center, the First Affiliated Hospital, Guangxi Medical University, Guangxi, Nanning 530021, China.
authors.forename: Miaoyu
authors.initials: M
authors.lastname: Yu
authors.affiliation: Mental Health Center, the First Affiliated Hospital, Guangxi Medical University, Guangxi, Nanning 530021, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Mental Health Center, the First Affiliated Hospital, Guangxi Medical University, Guangxi, Nanning 530021, China.
authors.forename: Changqing
authors.initials: C
authors.lastname: Xiao
authors.affiliation: Mental Health Institute of the Second Xiangya Hospital, Key Laboratory of Psychiatry and Mental Health of Hunan Province, Central South University, Hunan, Changsha 410011, China.
authors.forename: Jingping
authors.initials: J
authors.lastname: Zhao
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002531:Cerebellum / Q000473:pathology* / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology*; D003865:Major Depressive Disorder / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D066128:Gray Matter / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008032:Limbic System / Q000473:pathology* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged
keywords: Causal effect; Functional connectivity; Granger causality analysis; Major depressive disorder; Structural deficits