title: Complexity of motor sequences and cortical reorganization in Parkinson's disease: a functional MRI study.
abstract: Motor impairment is the most relevant clinical feature in Parkinson's disease (PD). Functional imaging studies on motor impairment in PD have revealed changes in the cortical motor circuits, with particular involvement of the fronto-striatal network. The aim of this study was to assess brain activations during the performance of three different motor exercises, characterized by progressive complexity, using a functional fMRI multiple block paradigm, in PD patients and matched control subjects. Unlike from single-task comparisons, multi-task comparisons between similar exercises allowed to analyse brain areas involved in motor complexity planning and execution. Our results showed that in the single-task comparisons the involvement of primary and secondary motor areas was observed, consistent with previous findings based on similar paradigms. Most notably, in the multi-task comparisons a greater activation of supplementary motor area and posterior parietal cortex in PD patients, compared with controls, was observed. Furthermore, PD patients, compared with controls, had a lower activation of the basal ganglia and limbic structures, presumably leading to the impairment in the higher levels of motor control, including complexity planning and execution. The findings suggest that in PD patients occur both compensatory mechanisms and loss of efficiency and provide further insight into the pathophysiological role of distinct cortical and subcortical areas in motor dysfunction.
authors.affiliation: Clinica Neurologica, Azienda Ospedaliera - Università di Perugia, Perugia, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Caproni
authors.forename: Marco
authors.initials: M
authors.lastname: Muti
authors.forename: Massimo
authors.initials: M
authors.lastname: Principi
authors.forename: Pierfausto
authors.initials: P
authors.lastname: Ottaviano
authors.forename: Domenico
authors.initials: D
authors.lastname: Frondizi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Capocchi
authors.forename: Piero
authors.initials: P
authors.lastname: Floridi
authors.forename: Aroldo
authors.initials: A
authors.lastname: Rossi
authors.forename: Paolo
authors.initials: P
authors.lastname: Calabresi
authors.forename: Nicola
authors.initials: N
authors.lastname: Tambasco
mesh_terms: D000368:Aged; D001519:Behavior / Q000502:physiology; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000502:physiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D010300:Parkinson Disease / Q000503:physiopathology*