title: Subthalamic nucleus stimulation modulates afferent inhibition in Parkinson disease.
abstract: BACKGROUND
  Peripheral sensory stimulation at the wrist inhibits the motor cortex as measured by transcranial magnetic stimulation at interstimulus intervals of approximately 20 ms (short latency afferent inhibition [SAI]) and 200 ms (long latency afferent inhibition [LAI]). Previous studies suggested that reduced SAI in Parkinson disease (PD) reflects adverse effect of dopaminergic medications and reduced LAI may be related to nondopaminergic manifestations of PD. We hypothesize that subthalamic nucleus (STN) deep brain stimulation (DBS) may correct these deficiencies.
  
  
  METHODS
  We studied the effects of STN DBS on SAI and LAI in seven PD patients and age-matched controls. PD patients were studied in an off medication followed by an on medication session, with the stimulator switched on or off in random order in each session.
  
  
  RESULTS
  In the on medication session, SAI was reduced in the stimulator off condition and was restored by STN DBS. LAI was partially normalized by STN DBS in the medication on condition.
  
  
  CONCLUSIONS
  Subthalamic nucleus (STN) stimulation improves short latency afferent inhibition, suggesting that it could normalize pathways that are adversely affected by dopaminergic medications. The effect of STN stimulation on long latency afferent inhibition suggests that it may influence nondopaminergic pathways involved in sensorimotor integration.
authors.affiliation: Division of Neurology, Krembil Neuroscience Centre and Toronto Western Research Institute, University of Toronto, Toronto, Ontario, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Sailer
authors.forename: D I
authors.initials: DI
authors.lastname: Cunic
authors.forename: G O
authors.initials: GO
authors.lastname: Paradiso
authors.forename: C A
authors.initials: CA
authors.lastname: Gunraj
authors.forename: A
authors.initials: A
authors.lastname: Wagle-Shukla
authors.forename: E
authors.initials: E
authors.lastname: Moro
authors.forename: A M
authors.initials: AM
authors.lastname: Lozano
authors.forename: A E
authors.initials: AE
authors.lastname: Lang
authors.forename: R
authors.initials: R
authors.lastname: Chen
mesh_terms: D000222:Adaptation, Physiological; D000344:Afferent Pathways / Q000503:physiopathology*; D046690:Deep Brain Stimulation / Q000379:methods*; D004562:Electrocardiography; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition; D009473:Neuronal Plasticity; D011930:Reaction Time; D020531:Subthalamic Nucleus / Q000503:physiopathology*