title: Subthalamic nucleus deep brain stimulation induces impulsive action when patients with Parkinson's disease act under speed pressure.
abstract: The subthalamic nucleus (STN) is proposed to modulate response thresholds and speed-accuracy trade-offs. In situations of conflict, the STN is considered to raise response thresholds, allowing time for the accumulation of information to occur before a response is selected. Conversely, speed pressure is thought to reduce the activity of the STN and lower response thresholds, resulting in fast, errorful responses. In Parkinson's disease (PD), subthalamic nucleus deep brain stimulation (STN-DBS) reduces the activity of the nucleus and improves motor symptoms. We predicted that the combined effects of STN stimulation and speed pressure would lower STN activity and lead to fast, errorful responses, hence resulting in impulsive action. We used the motion discrimination 'moving-dots' task to assess speed-accuracy trade-offs, under both speed and accuracy instructions. We assessed 12 patients with PD and bilateral STN-DBS and 12 age-matched healthy controls. Participants completed the task twice, and the patients completed it once with STN-DBS on and once with STN-DBS off, with order counterbalanced. We found that STN stimulation was associated with significantly faster reaction times but more errors under speed instructions. Application of the drift diffusion model showed that stimulation resulted in lower response thresholds when acting under speed pressure. These findings support the involvement of the STN in the modulation of speed-accuracy trade-offs and establish for the first time that speed pressure alone, even in the absence of conflict, can result in STN stimulation inducing impulsive action in PD.
authors.affiliation: Unit of Functional Neurosurgery, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, 33 Queen Square, London, WC1N 3BG, UK.|Cognitive Motor Neuroscience Group, UCL Institute of Neurology, London, WC1N 3BG, UK.|Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, SE5 8AF, UK.
authors.forename: Inês
authors.initials: I
authors.lastname: Pote
authors.affiliation: Unit of Functional Neurosurgery, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, 33 Queen Square, London, WC1N 3BG, UK.|Cognitive Motor Neuroscience Group, UCL Institute of Neurology, London, WC1N 3BG, UK.
authors.forename: Mariam
authors.initials: M
authors.lastname: Torkamani
authors.affiliation: Unit of Functional Neurosurgery, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, 33 Queen Square, London, WC1N 3BG, UK.
authors.forename: Zinovia-Maria
authors.initials: ZM
authors.lastname: Kefalopoulou
authors.affiliation: Unit of Functional Neurosurgery, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, 33 Queen Square, London, WC1N 3BG, UK.
authors.forename: Ludvic
authors.initials: L
authors.lastname: Zrinzo
authors.affiliation: Unit of Functional Neurosurgery, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, 33 Queen Square, London, WC1N 3BG, UK.
authors.forename: Patricia
authors.initials: P
authors.lastname: Limousin-Dowsey
authors.affiliation: Unit of Functional Neurosurgery, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, 33 Queen Square, London, WC1N 3BG, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Foltynie
authors.affiliation: Experimental Psychology, University College London, London, WC1H 0AP, UK.
authors.forename: Maarten
authors.initials: M
authors.lastname: Speekenbrink
authors.affiliation: Unit of Functional Neurosurgery, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, 33 Queen Square, London, WC1N 3BG, UK. m.jahanshahi@ucl.ac.uk.|Cognitive Motor Neuroscience Group, UCL Institute of Neurology, London, WC1N 3BG, UK. m.jahanshahi@ucl.ac.uk.
authors.forename: Marjan
authors.initials: M
authors.lastname: Jahanshahi
mesh_terms: D000368:Aged; D046690:Deep Brain Stimulation / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007175:Impulsive Behavior / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000628:therapy*; D011597:Psychomotor Performance / Q000502:physiology*; D020531:Subthalamic Nucleus / Q000502:physiology* / Q000503:physiopathology
keywords: Deep brain stimulation; Impulsivity; Parkinson’s disease; Response threshold; Speed–accuracy trade-off; Subthalamic nucleus