title: Akinetic-rigid and tremor-dominant Parkinson's disease patients show different patterns of intrinsic brain activity.
abstract: BACKGROUND
  Parkinson's disease (PD) is a surprisingly heterogeneous neurodegenerative disorder. It is well established that different subtypes of PD present with different clinical courses and prognoses. However, the neural mechanism underlying these disparate presentations is uncertain.
  
  
  METHODS
  Here we used resting-state fMRI (rs-fMRI) and the regional homogeneity (ReHo) method to determine neural activity patterns in the two main clinical subgroups of PD (akinetic-rigid and tremor-dominant).
  
  
  RESULTS
  Compared with healthy controls, akinetic-rigid (AR) subjects had increased ReHo mainly in right amygdala, left putamen, bilateral angular gyrus, bilateral medial prefrontal cortex (MPFC), and decreased ReHo in left post cingulate gyrus/precuneus (PCC/PCu) and bilateral thalamus. In contrast, tremor-dominant (TD) patients showed higher ReHo mostly in bilateral angular gyrus, left PCC, cerebellum_crus1, and cerebellum_6, while ReHo was decreased in right putamen, primary sensory cortex (S1), vermis_3, and cerebellum_4_5. These results indicate that AR and TD subgroups both represent altered spontaneous neural activity in default-mode regions and striatum, and AR subjects exhibit more changed neural activity in the mesolimbic cortex (amygdala) but TD in the cerebellar regions. Of note, direct comparison of the two subgroups revealed a distinct ReHo pattern primarily located in the striatal-thalamo-cortical (STC) and cerebello-thalamo-cortical (CTC) loops.
  
  
  CONCLUSIONS
  Overall, our findings highlight the involvement of default mode network (DMN) and STC circuit both in AR and TD subtypes, but also underscore the importance of integrating mesolimbic-striatal and CTC loops in understanding neural systems of akinesia and rigidity, as well as resting tremor in PD. This study provides improved understanding of the pathophysiological models of different subtypes of PD.
authors.affiliation: Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China.
authors.forename: Jiuquan
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China. Electronic address: weiluqing1212@gmail.com.
authors.forename: Luqing
authors.initials: L
authors.lastname: Wei
authors.affiliation: Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China.
authors.forename: Bing
authors.initials: B
authors.lastname: Xie
authors.affiliation: Department of Neurology, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Personality and Cognition, Faculty of Psychology, Southwest University, Beibei, Chongqing 400715, PR China; Faculty of Psychology and Educational Sciences, Department of Data Analysis, Ghent University, Henri Dunantlaan 1, B-9000 Ghent, Belgium.
authors.forename: Guo-Rong
authors.initials: GR
authors.lastname: Wu
authors.affiliation: Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China. Electronic address: wangjian811@gmail.com.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
mesh_terms: D000368:Aged; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D009127:Muscle Rigidity / Q000209:etiology*; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010300:Parkinson Disease / Q000150:complications*; D012146:Rest; D014202:Tremor / Q000209:etiology* / Q000473:pathology*
chemical_list: D010100:Oxygen
keywords: Akinetic-rigid; Parkinson's disease; Regional homogeneity; Resting-state fMRI; Tremor-dominant