title: Effective connectivity of the posterior cingulate and medial prefrontal cortices relates to working memory impairment in schizophrenic and bipolar patients.
abstract: BACKGROUND
  Schizophrenia (SZ) and bipolar I disorder (BD) share many overlapping clinical features, confounding the current diagnostic systems. Recent studies suggest the posterior cingulate (PCC) and medial prefrontal (MPFC) cortices that are involved in SZ and BD pathophysiology. However, the roles of PCC and MPFC in providing specific distinctive and shared neural substrates between these two disorders remain largely unknown. Examining the neurophysiologic mechanism of these diseases may help explain the clinical observations and differentiate the two disorders.
  
  
  METHODS
  We used the Dynamic Casual Modeling (DCM), which is capable of eliciting hidden neuronal dynamics and reveal cross-regulation of multiple neuronal systems, to characterize the pattern of disrupted effective connectivity in the left PCC-MPFC circuit during working memory tasks in 36 SZ and 20 BD patients as well as 29 healthy controls.
  
  
  RESULTS
  Compared to the healthy controls, both SZ and BD patient groups exhibited significant negative effective connectivity from the left MPFC to PCC. The negative effective connectivity was more remarkable in schizophrenic patients. Only patients with BD differed from healthy controls with positive effective connectivity from the left PCC to MPFC.
  
  
  CONCLUSIONS
  Whole brain analysis revealed deactivation of the left PCC and MPFC across all patient groups. This study provides new insight that changes in effective connectivity of the left MPFC to left PCC circuit during working memory processing may be a core pathophysiological feature distinguishing SZ from BD.
authors.affiliation: Institute of Mental Health, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Wu
authors.affiliation: Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Institute of Mental Health, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China; College of Health Sciences, University of Dodoma, P.O. Box 395, Dodoma, Tanzania.
authors.forename: Tumbwene E
authors.initials: TE
authors.lastname: Mwansisya
authors.affiliation: Institute of Mental Health, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China.
authors.forename: Weidan
authors.initials: W
authors.lastname: Pu
authors.affiliation: Institute of Mental Health, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China.
authors.forename: Huiran
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute of Mental Health, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Psychiatry, Yale School of Medicine, New Haven, CT 06520, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Department of Psychiatry, University of Hong Kong, Hong Kong, China.
authors.forename: Eric Y H
authors.initials: EY
authors.lastname: Chen
authors.affiliation: Institute of Mental Health, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Xue
authors.affiliation: Institute of Mental Health, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China; State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan 410011, China. Electronic address: zningl@163.com.
authors.forename: Zhening
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing 100049, China. Electronic address: shanbc@ihep.ac.cn.
authors.forename: Baoci
authors.initials: B
authors.lastname: Shan
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000188:drug therapy / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006179:Gyrus Cinguli / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000503:physiopathology*; D008570:Memory, Short-Term / Q000502:physiology*; D008959:Models, Neurological; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D017397:Prefrontal Cortex / Q000503:physiopathology*; D012559:Schizophrenia / Q000188:drug therapy / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
keywords: Bipolar disorder; Cognition; Dynamic causal modeling; Effective connectivity; Schizophrenia