title: Motor facilitation during real-time movement imitation in Parkinson's disease: a virtual reality study.
abstract: BACKGROUND
  Impaired temporal stability and poor motor unit recruitment are key impairments in Parkinsonian motor control during a whole spectrum of rhythmic movements, from simple finger tapping to gait. Therapies based on imitation can be designed for patients with motor impairments and virtual-reality (VR) offers a new perspective. Motor actions are known to depend upon the dopaminergic system, whose involvement in imitation is unknown. We sought to understand this role and the underlying possibilities for motor rehabilitation, by observing the execution of different motor-patterns during imitation in a VR environment in subjects with and without dopaminergic deficits.
  
  
  METHODS
  10 OFF-dose idiopathic Parkinson's Disease patients (PD), 9 age-matched and 9 young-subjects participated. Subjects performed finger-tapping at their "comfort" and "slow-comfort" rates, while immersed in VR presenting their "avatar" in 1st person perspective. Imitation was evaluated by asking subjects to replicate finger-tapping patterns different to their natural one. The finger-pattern presented matched their comfort and comfort-slow rates, but without a pause on the table (continuously moving).
  
  
  RESULTS
  Patients were able to adapt their finger-tapping correctly, showing that in comparison with the control groups, the dopaminergic deficiency of PD did not impair imitation. During imitation the magnitude of EMG increased and the temporal variability of movement decreased.
  
  
  CONCLUSIONS
  PD-patients have unaltered ability to imitate instructed motor-patterns, suggesting that a fully-functional dopaminergic system is not essential for such imitation. It should be further investigated if imitation training over a period of time induces positive off-line motor adaptations with transfer to non-imitation tasks.
authors.affiliation: Neuroscience and Motor Control Group (NEUROcom), Department of Medicine, INEF-Galicia and Institute of Biomedical Research of Coruña (INIBIC), University of A Coruña, 15006 A Coruña, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Robles-García
authors.forename: Pablo
authors.initials: P
authors.lastname: Arias
authors.forename: Gabriel
authors.initials: G
authors.lastname: Sanmartín
authors.forename: Nelson
authors.initials: N
authors.lastname: Espinosa
authors.forename: Julian
authors.initials: J
authors.lastname: Flores
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Grieve
authors.forename: Javier
authors.initials: J
authors.lastname: Cudeiro
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007100:Imitative Behavior / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D010300:Parkinson Disease / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D063367:Virtual Reality Exposure Therapy
keywords: Imitative behavior; Movement; Parkinson's disease; Virtual environment