title: The subthalamic nucleus and inhibitory control: impact of subthalamotomy in Parkinson's disease.
abstract: The aim of our study was to investigate two inter-related hypotheses about the role of the subthalamic nucleus. First that the subthalamic nucleus plays a role in adjusting response thresholds and speed-accuracy trade-offs and second that it is involved in reactive and proactive inhibition and conflict resolution. These were addressed by comparing the performance of 10 patients with Parkinson's disease treated with right subthalamotomy and 12 patients with left subthalamotomy, to 14 unoperated patients with Parkinson's disease and 23 age-matched healthy control participants on a conditional stop signal task and applying the drift diffusion model. Unilateral subthalamotomy significantly improved Parkinson's disease motor signs. Patients with right subthalamotomy had significantly faster Go reaction times with their contra-lesional hand than the unoperated patients and did not differ from the control participants, indicating their speed of response initiation was 'normalized'. However, operated patients made significantly more discrimination errors than unoperated patients and controls, suggesting that subthalamotomy influenced speed-accuracy trade-offs. This was confirmed by the drift diffusion model, revealing that while the unoperated patients had significantly lower drift rate and higher response thresholds than the control participants, the response thresholds for the operated groups did not differ from the controls and the patients with right subthalamotomy had a significantly higher drift rate than unoperated patients and similar to that of controls. The drift diffusion model further established that unlike the control participants, operated patients failed to show context-dependent strategic modulation of response thresholds. The patients with right subthalamotomy could not engage in late phase, fast inhibition of the response and showed minimal proactive inhibition when tested with the contra-lesional hand. These results provide strong evidence that the subthalamic nucleus is involved in response inhibition, in modulating the rate of information accumulation and the response threshold and influencing the balance between speed and accuracy of performance. Accordingly, the subthalamic nucleus can be considered a key component of the cerebral inhibitory network.
authors.affiliation: 1 Cognitive-Motor Neuroscience Group and the Functional Neurosurgery Unit, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology and The National Hospital for Neurology and Neurosurgery, WC1N 3BG, UK.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Obeso
authors.forename: Leonora
authors.initials: L
authors.lastname: Wilkinson
authors.forename: Enrique
authors.initials: E
authors.lastname: Casabona
authors.forename: Maarten
authors.initials: M
authors.lastname: Speekenbrink
authors.forename: María
authors.initials: M
authors.lastname: Luisa Bringas
authors.forename: Mario
authors.initials: M
authors.lastname: Álvarez
authors.forename: Lázaro
authors.initials: L
authors.lastname: Álvarez
authors.forename: Nancy
authors.initials: N
authors.lastname: Pavón
authors.forename: María C
authors.initials: MC
authors.lastname: Rodríguez-Oroz
authors.forename: Raúl
authors.initials: R
authors.lastname: Macías
authors.forename: Jose A
authors.initials: JA
authors.lastname: Obeso
authors.forename: Marjan
authors.initials: M
authors.lastname: Jahanshahi
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery*; D011930:Reaction Time / Q000502:physiology; D017603:Signal Detection, Psychological; D020531:Subthalamic Nucleus / Q000502:physiology* / Q000601:surgery*; D016896:Treatment Outcome
keywords: Parkinson’s disease; response inhibition; response thresholds; stop signal task; subthalamic nucleus