title: Neural correlates of progressive reduction of bradykinesia in de novo Parkinson's disease.
abstract: BACKGROUND
  A progressive reduction in the speed and amplitude of repetitive action is an essential component of bradykinesia, which is called sequence effect (SE). Because SE is specific to Parkinson's disease (PD) and is suggested to be associated with motor arrest, its features are of great interest. The aim of this study was, for the first time, to find the neural correlates of SE and to demonstrate whether dopaminergic deficit is correlated with SE.
  
  
  METHODS
  We enrolled 12 patients with de novo PD at a tertiary referral hospital. Correlations between SE severity and alterations in gray and white matter were studied. The association between severity of the SE and striatal dopaminergic deficits was also analyzed.
  
  
  RESULTS
  There was a significant negative correlation between the volumetric changes in the anterior cingulate cortex (ACC) and the inferior semilunar lobule of the cerebellum and the degree of SE. There was a significant correlation between the long association fibers (the superior longitudinal fasciculus, the uncinate fasciculus, and the inferior fronto-occipital fasciculus) connecting the frontal lobes to the temporal, parietal, and occipital lobes and SE. There was a significant negative correlation between SE in the more affected hand and the caudate dopamine transporter binding in the more affected hemisphere.
  
  
  CONCLUSIONS
  Our results suggest that the ACC and the cerebellum (inferior semilunar lobule) are associated with the severity of SE. Taken together with DTI findings, the present study proposes that ACC may have an important role. Our data show that the caudate dopaminergic activity may be related to SE.
authors.affiliation: Graduate School of Medical Science & Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea; Laboratory for Cognitive Neuroscience and Neuroimaging, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea.
authors.forename: Eeksung
authors.initials: E
authors.lastname: Lee
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Lee
authors.affiliation: Laboratory for Cognitive Neuroscience and Neuroimaging, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea.
authors.forename: Kwangsun
authors.initials: K
authors.lastname: Yoo
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; Department of Neurology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
authors.forename: Jin Yong
authors.initials: JY
authors.lastname: Hong
authors.affiliation: Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Jungsu
authors.initials: J
authors.lastname: Oh
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; Department of Neurology, Bundang Jesaeng Hospital, Seongnam-si, Gyeonggi-do, Republic of Korea.
authors.forename: Mun Kyung
authors.initials: MK
authors.lastname: Sunwoo
authors.affiliation: Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Laboratory for Cognitive Neuroscience and Neuroimaging, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea.
authors.forename: Yong
authors.initials: Y
authors.lastname: Jeong
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Phil Hyu
authors.initials: PH
authors.lastname: Lee
authors.affiliation: Department of Neurology and Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Sohn
authors.affiliation: Department of Neurology, Dongtan Sacred Heart Hospital, Hallym University College of Medicine, 7, Keunjaebong-gil, Hwaseong-si, Gyeonggi-do 445-907, Republic of Korea. Electronic address: sukyunkang@yahoo.co.kr.
authors.forename: Suk Yun
authors.initials: SY
authors.lastname: Kang
mesh_terms: D000368:Aged; D016880:Anisotropy; D001931:Brain Mapping; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000503:physiopathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D009413:Nerve Fibers, Myelinated / Q000000981:diagnostic imaging / Q000502:physiology*; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D049268:Positron-Emission Tomography; D012044:Regression Analysis; D014326:Tropanes; D014463:Ultrasonography
chemical_list: D014326:Tropanes; C087552:2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane
keywords: Diffusion tensor imaging; Dopamine; Magnetic resonance imaging; Parkinson's disease; Sequence effect