title: Dopa therapy and action impulsivity: subthreshold error activation and suppression in Parkinson's disease.
abstract: BACKGROUND
  Impulsive actions entail (1) capture of the motor system by an action impulse, which is an urge to act and (2) failed suppression of that impulse in order to prevent a response error. Several studies indicate that dopaminergic treatment can induce action impulsivity in patients diagnosed with Parkinson's disease (PD). Whether this effect is due to increased impulse expression or to decreased impulse suppression remains to be deciphered.
  
  
  METHODS
  We used a novel approach based on electromyographic (EMG) analyses to decipher the effects of the patient's usual dopaminergic therapy on the expression and suppression of subliminal erroneous impulses. To this end, we used a within-subject design and took advantage of the Simon task, that elicits prepotent response tendencies. The patients (N = 15) performed the task on their usual dopaminergic medication and after complete medication withdrawal (for at least 12 h).
  
  
  RESULTS
  The correction rate that measures the ability to suppress subthreshold impulsive muscle activity was lower when the patients were on medication as compared to their off medication state (p < 0.05). The incorrect activation rate that measures the capture of the motor system by action impulses was unaffected by medication.
  
  
  CONCLUSIONS
  Dopa therapy affected action impulsivity. Although medication did not influence the incidence of fast action impulses, it significantly reduced patients' ability to abort and suppress muscle activation related to the incorrect response alternative.
authors.affiliation: Laboratoire de Neurosciences Cognitives, Fédération de Recherche Comportement-Cerveau-Cognition, Aix-Marseille Université, CNRS, Marseille, France, frederique.fluchere@ap-hm.fr.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Fluchère
authors.forename: Manon
authors.initials: M
authors.lastname: Deveaux
authors.forename: Borís
authors.initials: B
authors.lastname: Burle
authors.forename: Franck
authors.initials: F
authors.lastname: Vidal
authors.forename: Wery P M
authors.initials: WP
authors.lastname: van den Wildenberg
authors.forename: Tatiana
authors.initials: T
authors.lastname: Witjas
authors.forename: Alexandre
authors.initials: A
authors.lastname: Eusebio
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Azulay
authors.forename: Thierry
authors.initials: T
authors.lastname: Hasbroucq
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000978:Antiparkinson Agents / Q000008:administration & dosage; D004298:Dopamine / Q000378:metabolism; D018491:Dopamine Agonists / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007175:Impulsive Behavior / Q000187:drug effects* / Q000502:physiology; D007980:Levodopa / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy* / Q000523:psychology*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000187:drug effects* / Q000502:physiology
chemical_list: D000978:Antiparkinson Agents; D018491:Dopamine Agonists; D007980:Levodopa; D004298:Dopamine