Retention of a novel visuomotor gain in patients with Parkinson's disease is context-specific
Contreras-Vidal, José L
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Hypometria or reduced movement amplitude is a major concern in Parkinson's disease (PD) since it impairs multiple functional activities of daily living, including fine motor control tasks, such as handwriting. Recent research using virtual or computer-based environments, wherein visual information about hand movement is altered and dissociated from perception (e.g., position sense or kinesthesia) of hand movement itself, has shown increases in handwriting size in patients with PD. In fact, preliminary findings in our laboratory have shown that gradual alterations in visual feedback of movement facilitate adaptation of handwriting size in patients with PD, plausibly by recruiting neural networks other than the basal ganglia, such as those in cerebellum. The purpose of this study was to determine whether these adaptive effects persist after a week following visuomotor training in patients with PD and can favorably transfer to other functional writing and drawing tasks. Thirteen patients with Parkinson's disease and twelve healthy, age-matched subjects practiced handwriting either under gradually manipulated (intervention) or intact (placebo) visual display of handwriting size. The results from this study show for the first time, that these adaptive effects may persist for at least up to a week in PD; however, a single training session seemed inadequate to transfer these acquired changes to paper-pen writing and drawing. Additionally, experimental manipulation of task demands during training also helped maintain movement quality in patients with PD as against the placebo group. These findings have important implications in designing rehabilitative interventions to enhance functional sensorimotor performance in patients with PD.