title: In Parkinson's disease pallidal deep brain stimulation speeds up response initiation but has no effect on reactive inhibition.
abstract: The fronto-striatal circuits are considered to mediate inhibitory control over action. The aim of this study was to investigate the contribution of the internal segment of the pallidum (GPi), one of the final output pathways from the basal ganglia to the cortex, in inhibition. We examined the effect of deep brain stimulation (DBS) of the GPi (GPi-DBS) in patients with Parkinson's disease who performed a conditional stop signal task, with DBS on and off. Modulation of GPi activity was associated with significantly faster Go reaction times with DBS on than off, but stop signal reaction times were not altered. Application of the drift diffusion model indicated that GPi-DBS was associated with significantly lower response thresholds compared to GPi-DBS off. However, the drift rate was significantly lower than healthy controls with both GPi-DBS on and off. These results suggest that the GPi plays a crucial role in the 'Go' pathway, perhaps facilitating reaching the required threshold to initiate actions. However, GPi-DBS does not alter the functioning of the indirect 'NoGo' pathway, and other basal ganglia nuclei, such as the STN, may play a greater role in reactive response inhibition and conflict resolution.
authors.affiliation: Functional Neurosurgery Unit, Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology and the National Hospital of Neurology and Neurosurgery, University College London, 33 Queen Square, London, WC1N 3BG, UK.
authors.forename: S
authors.initials: S
authors.lastname: Kohl
authors.forename: K
authors.initials: K
authors.lastname: Aggeli
authors.forename: I
authors.initials: I
authors.lastname: Obeso
authors.forename: M
authors.initials: M
authors.lastname: Speekenbrink
authors.forename: P
authors.initials: P
authors.lastname: Limousin
authors.forename: J
authors.initials: J
authors.lastname: Kuhn
authors.forename: M
authors.initials: M
authors.lastname: Jahanshahi
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D046690:Deep Brain Stimulation / Q000379:methods*; D005260:Female; D005917:Globus Pallidus / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000628:therapy*; D011334:Proactive Inhibition; D011930:Reaction Time / Q000502:physiology*; D011931:Reactive Inhibition; D016896:Treatment Outcome