title: Determining the optimal challenge point for motor skill learning in adults with moderately severe Parkinson's disease.
abstract: OBJECTIVE
  To test the predictions of the Challenge Point Framework (CPF) for motor learning in individuals with Parkinson's disease (PD) by manipulating nominal task difficulty and conditions of practice.
  
  
  METHODS
  Twenty adults with PD and 20 nondisabled controls practiced 3 variations of a laboratory-based goal-directed arm movement over 2 days. A between-group (PD, nondisabled) 2-factor design compared 2 levels of nominal task difficulty (low, high) and 2 levels of practice condition (low, high demand). Learning was assessed with a no-feedback recall test 1 day after practice. Performance was quantified using a root mean square error difference between the goal and participant-generated movement.
  
  
  RESULTS
  All participants improved with practice. Under the low-demand practice condition, adults with PD demonstrated comparable learning to that of controls when nominal task difficulty was low but not high. In contrast, under the high-demand practice condition, adults with PD demonstrated preserved motor learning for both levels of task difficulty, but only if recall was tested under the same context as that used during practice.
  
  
  CONCLUSIONS
  In general, the predictions of CPF were supported. Together, the level of nominal task difficulty and the inherent demand of the practice condition played a critical role in determining the optimal challenge point for motor learning in individuals with PD. More important, and in contrast to the predictions of CPF, a high-demand practice condition appeared to have a facilitative effect on motor learning. However, this benefit revealed the context specificity of motor learning in adults with PD.
authors.affiliation: Department of Physical Therapy, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand. onlaor@chiangmai.ac.th
authors.forename: Somporn
authors.initials: S
authors.lastname: Onla-or
authors.forename: Carolee J
authors.initials: CJ
authors.lastname: Winstein
mesh_terms: D000368:Aged; D018450:Disease Progression; D005081:Exercise Therapy / Q000379:methods*; D006801:Humans; D007858:Learning / Q000502:physiology; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology; D010300:Parkinson Disease / Q000503:physiopathology* / Q000534:rehabilitation*; D010809:Physical Fitness; D026741:Physical Therapy Modalities; D011340:Problem Solving; D012720:Severity of Illness Index