title: Cerebellar stroke impairs temporal but not spatial accuracy during implicit motor learning.
abstract: OBJECTIVE
  Numerous studies have demonstrated cerebellar activity during implicit motor learning, but few have addressed its specific role. The purpose of this study was to determine if specific components (spatial or temporal) of an implicit motor-tracking task were affected by cerebellar stroke.
  
  
  METHODS
  The authors studied the performance of individuals with unilateral cerebellar stroke (n = 7)and a control group (n = 10) across 3 acquisition days and at a delayed retention test as they practiced a unimanual tracking task with the contralesional upper extremity.
  
  
  RESULTS
  After cerebellar stroke, participants demonstrated reduced tracking errors for repeating sequences compared to random sequences; however, decomposition of tracking performance into temporal and spatial components revealed persistent deficits in tracking time lag despite improved spatial accuracy. A lesion analysis showed that the dentate nucleus was the only common region affected by all cerebellar strokes.
  
  
  CONCLUSIONS
  During implicit motor learning, the cerebellum appears to participate in the formation of predictive strategies for the timing of motor responses, rather than for the accuracy of motor execution. Because deficits were found in the contralesional upper extremity, the authors suggest that this function is not lateralized to 1 hemisphere; cerebellar output may affect the formation of an internal model for timing movements in both upper extremities.
authors.affiliation: Department of Physical Therapy and Rehabilitation Sciences, University of Kansas Medical Center, 3056 Robinson, Mail Stop 2002, 3901 Rainbow Boulevard, Kansas City 66160-7601, USA. Lboyd@kumc.edu
authors.forename: Lara A
authors.initials: LA
authors.lastname: Boyd
authors.forename: Carolee J
authors.initials: CJ
authors.lastname: Winstein
mesh_terms: D000328:Adult; D000368:Aged; D002526:Cerebellar Diseases / Q000175:diagnosis / Q000523:psychology*; D005260:Female; D006801:Humans; D007858:Learning; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009048:Motor Skills; D011597:Psychomotor Performance; D013028:Space Perception; D020521:Stroke / Q000175:diagnosis / Q000523:psychology*; D013998:Time Perception; D014057:Tomography, X-Ray Computed