title: Behavioral inflexibility and motor dedifferentiation in persons with Parkinson's disease: bilateral coordination deficits during a unimanual reaching task.
abstract: We evaluated kinematics of people with Parkinson's disease (PD) and age-matched controls during cued and uncued reaching movements. Maximum hand velocity, its variability and shoulder-to-shoulder coupling, quantified by phase locking value (PLV), were compared between PD (n=14) and Control (n=4). The PD group achieved significantly lower maximum hand velocities during the reaching movement in comparison to the Control group (p=0.05), whereas the Control group exhibited significantly greater variability (i.e., larger SDs) of maximum hand velocities across the blocks than the PD group (p=0.01). Persons with PD exhibited higher PLVs than the healthy elderly individuals when performing reaching movements with their dominant side (p=0.05), while the PLVs did not differ between groups when the movements were performed with their non-dominant hand. The present study suggests that persons with PD have a reduced ability to: (1) modulate maximum reaching velocity; and (2) alter coordination across the shoulders to different reaching actions. In persons with PD, the velocity-oriented (dominant) limb becomes slowed and less flexible, to the point that its movement dynamics are effectively similar to that of the position-oriented (non-dominant) limb.
authors.affiliation: Department of Biomedical Sciences, Ohio University, Athens, OH, USA.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Amano
authors.affiliation: Department of Biomedical Sciences, Ohio University, Athens, OH, USA.
authors.forename: S Lee
authors.initials: SL
authors.lastname: Hong
authors.affiliation: Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA.
authors.forename: Jacob I
authors.initials: JI
authors.lastname: Sage
authors.affiliation: Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA. Electronic address: ebtorres@rci.rutgers.edu.
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: Torres
mesh_terms: D000368:Aged; D001259:Ataxia / Q000503:physiopathology / Q000523:psychology*; D001519:Behavior; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D007839:Functional Laterality; D006225:Hand / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D010300:Parkinson Disease / Q000503:physiopathology / Q000523:psychology*; D011597:Psychomotor Performance; D012782:Shoulder / Q000503:physiopathology
keywords: Behavioral inflexibility; Bradykinesia; Motor dedifferentiation; Motor freezing; Parkinson's disease; Phase synchrony