title: Disrupted connectivity of motor loops in Parkinson's disease during self-initiated but not externally-triggered movements.
abstract: Parkinson's disease (PD) reportedly includes altered connectivity of neural loops involving the basal ganglia and cerebellum, although little is known regarding any changes in the connectivity of motor loops. The goal of this study was to further understand the connectivity within the basal ganglia-thalamo-motor (BGTM) and cerebro-cerebellar (CC) loops in PD. Twelve PD patients and 12 age-matched control subjects performed a protocol involving self-initiated (SI) and externally-triggered (ET) finger movements, while being scanned with functional magnetic resonance imaging. Compared with the control subjects, the PD subjects showed hypo-activation in the bilateral putamen, right supplementary motor area and hyper-activation in the right premotor cortex. In the sensorimotor cortex and cerebellar hemisphere, PD subjects tended to show hyper-activation in a main effects analysis, but hypo-activation in a linear effects analysis. Analysis using structural equation modeling (SEM) revealed significant positive interactions within the right BGTM loop during the SI task and within the right (right cerebral hemisphere-left cerebellum) CC loop during the ET task. SEM also revealed task-related quantitative changes between the thalamus and the motor cortices in the control subjects. We found that the PD patients showed reduced connectivity in the right BGTM loop and inter-hemispheric connections in SEM, which is the first demonstration of this phenomenon. Interestingly, PD patients exhibited preserved connectivity within the right CC loop during the ET task. These results suggest disruption of cortico-striatal processing and preservation of relatively intact neural circuits that do not involve the basal ganglia in PD.
authors.affiliation: Division of Respirology, Neurology and Rheumatology, Department of Medicine, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, Fukuoka 830-0011, Japan. ttaniwa@med.kurume-u.ac.jp
authors.forename: Takayuki
authors.initials: T
authors.lastname: Taniwaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshiura
authors.forename: Katsuya
authors.initials: K
authors.lastname: Ogata
authors.forename: Osamu
authors.initials: O
authors.lastname: Togao
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Yamashita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kida
authors.forename: Sirou
authors.initials: S
authors.lastname: Miura
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Kira
authors.forename: Shouzo
authors.initials: S
authors.lastname: Tobimatsu
mesh_terms: D000368:Aged; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D003463:Cues; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D009434:Neural Pathways / Q000098:blood supply / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D010300:Parkinson Disease / Q000473:pathology* / Q000523:psychology
chemical_list: D010100:Oxygen