title: Normalizing motor-related brain activity: subthalamic nucleus stimulation in Parkinson disease.
abstract: OBJECTIVE
  To test whether therapeutic unilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients with Parkinson disease (PD) leads to normalization in the pattern of brain activation during movement execution and control of movement extent.
  
  
  METHODS
  Six patients with PD were imaged off medication by PET during performance of a visually guided tracking task with the DBS voltage programmed for therapeutic (effective) or subtherapeutic (ineffective) stimulation. Data from patients with PD during ineffective stimulation were compared with a group of 13 age-matched control subjects to identify sites with abnormal patterns of activation. Conjunction analysis was used to identify those areas in patients with PD where activity normalized when they were treated with effective stimulation.
  
  
  RESULTS
  For movement execution, effective DBS caused an increase of activation in the supplementary motor area (SMA), superior parietal cortex, and cerebellum toward a more normal pattern. At rest, effective stimulation reduced overactivity of SMA. Therapeutic stimulation also induced reductions of movement related "overactivity" compared with healthy subjects in prefrontal, temporal lobe, and basal ganglia circuits, consistent with the notion that many areas are recruited to compensate for ineffective motor initiation. Normalization of activity related to the control of movement extent was associated with reductions of activity in primary motor cortex, SMA, and basal ganglia.
  
  
  CONCLUSIONS
  Effective subthalamic nucleus stimulation leads to task-specific modifications with appropriate recruitment of motor areas as well as widespread, nonspecific reductions of compensatory or competing cortical activity.
authors.affiliation: Center for Cognitive Neuroscience, Dartmouth College, Hanover, NH 03755, USA. scott.t.grafton@dartmouth.edu
authors.forename: S T
authors.initials: ST
authors.lastname: Grafton
authors.forename: R S
authors.initials: RS
authors.lastname: Turner
authors.forename: M
authors.initials: M
authors.lastname: Desmurget
authors.forename: R
authors.initials: R
authors.lastname: Bakay
authors.forename: M
authors.initials: M
authors.lastname: Delong
authors.forename: J
authors.initials: J
authors.lastname: Vitek
authors.forename: M
authors.initials: M
authors.lastname: Crutcher
mesh_terms: D000328:Adult; D000368:Aged; D002560:Cerebrovascular Circulation / Q000502:physiology; D046690:Deep Brain Stimulation; D005260:Female; D005917:Globus Pallidus / Q000098:blood supply / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000473:pathology / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D020531:Subthalamic Nucleus / Q000098:blood supply / Q000503:physiopathology*; D013788:Thalamus / Q000098:blood supply / Q000503:physiopathology