title: Controlling your impulses: electrical stimulation of the human supplementary motor complex prevents impulsive errors.
abstract: To err is human. However, an inappropriate urge does not always result in error. Impulsive errors thus entail both a motor system capture by an urge to act and a failed inhibition of that impulse. Here we show that neuromodulatory electrical stimulation of the supplementary motor complex in healthy humans leaves action urges unchanged but prevents them from turning into overt errors. Subjects performed a choice reaction-time task known to trigger impulsive responses, leading to fast errors that can be revealed by analyzing accuracy as a function of poststimulus time. Yet, such fast errors are only the tip of the iceberg: electromyography (EMG) revealed fast subthreshold muscle activation in the incorrect response hand in an even larger proportion of overtly correct trials, revealing covert response impulses not discernible in overt behavior. Analyzing both overt and covert response tendencies enables to gauge the ability to prevent these incorrect impulses from turning into overt action errors. Hyperpolarizing the supplementary motor complex using transcranial direct current stimulation (tDCS) preserves action impulses but prevents their behavioral expression. This new combination of detailed behavioral, EMG, and tDCS techniques clarifies the neurophysiology of impulse control, and may point to avenues for improving impulse control deficits in various neurologic and psychiatric disorders.
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique, LNC Unité Mixte de Recherche 7291, 13331 Marseille Cedex 3, France, Laure.Spieser@city.ac.uk boris.burle@univ-amu.fr.
authors.forename: Laure
authors.initials: L
authors.lastname: Spieser
authors.affiliation: Amsterdam Center for the study of Adaptive Control in Brain and Behavior (Acacia), University of Amsterdam, 1018 XA Amsterdam, the Netherlands, and Amsterdam Brain & Cognition, University of Amsterdam, 1018 WB Amsterdam, the Netherlands.
authors.forename: Wery
authors.initials: W
authors.lastname: van den Wildenberg
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique, LNC Unité Mixte de Recherche 7291, 13331 Marseille Cedex 3, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Hasbroucq
authors.affiliation: Amsterdam Center for the study of Adaptive Control in Brain and Behavior (Acacia), University of Amsterdam, 1018 XA Amsterdam, the Netherlands, and Amsterdam Brain & Cognition, University of Amsterdam, 1018 WB Amsterdam, the Netherlands.
authors.forename: K Richard
authors.initials: KR
authors.lastname: Ridderinkhof
authors.affiliation: Aix-Marseille Université, Centre National de la Recherche Scientifique, LNC Unité Mixte de Recherche 7291, 13331 Marseille Cedex 3, France, Laure.Spieser@city.ac.uk boris.burle@univ-amu.fr.
authors.forename: Borís
authors.initials: B
authors.lastname: Burle
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001703:Biophysics; D002755:Choice Behavior / Q000502:physiology; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D007175:Impulsive Behavior / Q000502:physiology*; D007266:Inhibition, Psychological; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*; D055815:Young Adult
keywords: conflict task; executive control; impulse control; partial errors; pre-SMA/SMA; tDCS