title: Schizophrenic patients and their unaffected siblings share increased resting-state connectivity in the task-negative network but not its anticorrelated task-positive network.
abstract: BACKGROUND
  Abnormal connectivity of the anticorrelated intrinsic networks, the task-negative network (TNN), and the task-positive network (TPN) is implicated in schizophrenia. Comparisons between schizophrenic patients and their unaffected siblings enable further understanding of illness susceptibility and pathophysiology. We examined the resting-state connectivity differences in the intrinsic networks between schizophrenic patients, their unaffected siblings, and healthy controls.
  
  
  METHODS
  Resting-state functional magnetic resonance images were obtained from 25 individuals in each subject group. The posterior cingulate cortex/precuneus and right dorsolateral prefrontal cortex were used as seed regions to identify the TNN and TPN through functional connectivity analysis. Interregional connectivity strengths were analyzed using overlapped intrinsic networks composed of regions common to all subject groups.
  
  
  RESULTS
  Schizophrenic patients and their unaffected siblings showed increased connectivity in the TNN between the bilateral inferior temporal gyri. By contrast, schizophrenic patients alone demonstrated increased connectivity between the posterior cingulate cortex/precuneus and left inferior temporal gyrus and between the ventral medial prefrontal cortex and right lateral parietal cortex in the TNN. Schizophrenic patients exhibited increased connectivity between the left dorsolateral prefrontal cortex and right inferior frontal gyrus in the TPN relative to their unaffected siblings, though this trend only approached statistical significance in comparison to healthy controls.
  
  
  CONCLUSIONS
  Resting-state hyperconnectivity of the intrinsic networks may disrupt network coordination and thereby contribute to the pathophysiology of schizophrenia. Similar, though milder, hyperconnectivity of the TNN in unaffected siblings of schizophrenic patients may contribute to the identification of schizophrenia endophenotypes and ultimately to the determination of schizophrenia risk genes.
authors.affiliation: Mental Health Institute, Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.
authors.forename: Haihong
authors.initials: H
authors.lastname: Liu
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Xuan
authors.initials: X
authors.lastname: Ouyang
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Yihui
authors.initials: Y
authors.lastname: Hao
authors.forename: Eric Y H
authors.initials: EY
authors.lastname: Chen
authors.forename: Tianzi
authors.initials: T
authors.lastname: Jiang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Zhening
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005625:Frontal Lobe / Q000473:pathology* / Q000503:physiopathology; D059907:Functional Neuroimaging; D006179:Gyrus Cinguli / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D010296:Parietal Lobe / Q000473:pathology* / Q000503:physiopathology; D017397:Prefrontal Cortex / Q000473:pathology* / Q000503:physiopathology; D012559:Schizophrenia / Q000473:pathology* / Q000503:physiopathology; D035781:Siblings; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000473:pathology* / Q000503:physiopathology