title: Altered spontaneous activity in the default-mode network and cognitive decline in chronic subcortical stroke.
abstract: OBJECTIVE
  The resting-state functional connectivity (rsFC) has been reported to be impaired in the default-mode network (DMN) in stroke patients. However, it remains unclear whether the regional homogeneity (ReHo) of spontaneous activity and gray matter volume (GMV) are also altered in the DMN in these patients. Here we investigated ReHo, rsFC and GMV changes in the DMN and their functional correlations in stroke patients.
  
  
  METHODS
  Eighteen patients with chronic subcortical stroke and 20 healthy controls underwent multi-modality MRI examinations to extract the DMN and to calculate the ReHo, rsFC and GMV. The ReHo difference in the DMN was compared between groups and brain regions with significant group differences in ReHo were extracted to calculate rsFC and GMV of these regions. Correlations of the cognitive or depressive scores with the imaging indices of the DMN that exhibit group differences were also investigated in stroke patients.
  
  
  RESULTS
  Compared with healthy controls, patients with stroke exhibited decreased ReHo in the posterior cingulate cortex (PCC) and decreased rsFC between the PCC and anterior cingulate cortex (ACC). There were no significant volumetric differences in the PCC or the whole DMN between the two groups. The ReHo (not the rsFC) of the PCC was correlated with cognitive decline even after controlling for depressive scores. Neither ReHo nor rsFC of the PCC was correlated with depressive severity in these patients.
  
  
  CONCLUSIONS
  These findings suggest that both regional spontaneous activity and their interactions are impaired in stroke patients and that the reduced ReHo of the PCC may underlie post-stroke cognitive decline.
authors.affiliation: Department of Radiology, Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Jingchun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Radiology, Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Qin
authors.affiliation: Department of Neurology, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Radiology, Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Neurology, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Xue
authors.affiliation: School of Medical Imaging, Tianjin Medical University, Tianjin 300070, China. Electronic address: ydzhangxj@126.com.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin 300052, China; School of Medical Imaging, Tianjin Medical University, Tianjin 300070, China. Electronic address: chunshuiyu@tijmu.edu.cn.
authors.forename: Chunshui
authors.initials: C
authors.lastname: Yu
mesh_terms: D000368:Aged; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods*; D016022:Case-Control Studies; D003071:Cognition; D003627:Data Interpretation, Statistical; D003863:Depression; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000503:physiopathology*
keywords: Cognition; Gray matter volume; Ischemic stroke; Regional homogeneity; Resting-state functional connectivity; fMRI