title: Dopamine alters tactile perception in Parkinson's disease.
abstract: BACKGROUND
  Abnormal somatosensory processing may contribute to motor impairments observed in Parkinson's disease (PD). Dopaminergic medications have been shown to alter somatosensory processing such that tactile perception is improved. In PD, it remains unclear whether the temporal sequencing of tactile stimuli is altered and if dopaminergic medications alter this perception.
  
  
  METHODS
  Somatosensory tactile perception was investigated using temporal order judgment in patients with Parkinson's disease on and off dopaminergic medications and in aged-matched healthy controls. Measures of temporal order judgment were acquired using computer controlled stimulation to digits 2 and 3 on the right hand and subjects were required to determine which stimuli occurred first. Two experimental tasks were compared, temporal order judgment without and with synchronization whereby digits 2 and 3 were vibrated synchronously in advance of the temporal order judgment sequence of stimuli.
  
  
  RESULTS
  Temporal order judgment in PD patients of and on medications were similar to controls. Temporal order judgment preceded by synchronous vibration impaired tactical acuity in controls and in PD patients off medications to similar degrees, but this perceptual impairment by synchronous vibration was not present in PD patients on medications.
  
  
  CONCLUSIONS
  These findings suggest that dopamine in PD reduces cortico-cortical connectivity with SI and this leads to changes in tactical sensitivity.
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Aimee J
authors.initials: AJ
authors.lastname: Nelson
authors.forename: Azra
authors.initials: A
authors.lastname: Premji
authors.forename: Navjot
authors.initials: N
authors.lastname: Rai
authors.forename: Tasnuva
authors.initials: T
authors.lastname: Hoque
authors.forename: Mark
authors.initials: M
authors.lastname: Tommerdahl
authors.forename: Robert
authors.initials: R
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015259:Dopamine Agents / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007600:Judgment / Q000187:drug effects / Q000502:physiology; D007980:Levodopa / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications*; D010468:Perceptual Disorders / Q000188:drug therapy* / Q000209:etiology*; D010812:Physical Stimulation / Q000379:methods; D011601:Psychophysics; D012189:Retrospective Studies; D055698:Touch Perception / Q000187:drug effects*
chemical_list: D015259:Dopamine Agents; D007980:Levodopa