Abstract
Background: Impulse control disorder is not uncommon in patients with Parkinson’s disease (PD) who are treated with dopamine replacement therapy and subthalamic deep brain stimulation (DBS). Internal globus pallidus (GPi)-DBS is increasingly used, but its role in inhibitory control has rarely been explored. In this study, we evaluated the effect of GPi-DBS on inhibitory control in PD patients.Methods: A stop-signal paradigm was used to test response initiation, proactive inhibition, and reactive inhibition. The subjects enrolled in the experiment were 27 patients with PD, of whom 13 had received only drug treatment and 14 had received bilateral GPi-DBS in addition to conventional medical treatment and 15 healthy individuals.Results: Our results revealed that with GPi-DBS on, patients with PD showed significantly faster responses than the other groups in trials where it was certain that no stop signal would be presented. Proactive inhibition was significantly different in the surgical patients with GPi-DBS on versus when GPi-DBS was off, in surgical patients with GPi-DBS on versus drug-treated patients, and in healthy controls versus drug-treated patients. Correlation analyses revealed that when GPi-DBS was on, there was a statistically significant moderate positive relationship between proactive inhibition and dopaminergic medication.Conclusion: GPi-DBS may lead to an increase in response initiation speed and improve the dysfunctional proactive inhibitory control observed in PD patients. Our results may help us to understand the role of the GPi in cortical-basal ganglia circuits.
Highlights
Impulse control disorders have been shown to occur in approximately 17% of patients with Parkinson’s disease (PD) who receive dopamine replacement therapy (Weintraub et al, 2010a)
Certain-go reaction times (RTs) were significantly shorter in the surgical PD patients with globus pallidus (GPi)-deep brain stimulation (DBS)-on than in the healthy controls [t(27) = −2.693, P = 0.006] and drug-treated patients [t(25) = −2.071, P = 0.024]. This indicates an immediate improvement in the performance of certain-go trials when GPiDBS was turned on
For uncertain-go trials, only one significant difference in RTs was observed: the uncertain-go RTs were significantly shorter in the drug-treated PD patients than in the healthy controls
Summary
Impulse control disorders have been shown to occur in approximately 17% of patients with PD who receive dopamine replacement therapy (Weintraub et al, 2010a). Prospective studies have shown that in patients with ICDs due to decreased or discontinued use of dopaminergic medication, DBS of the STN can improve ICD symptoms (Lhommée et al, 2012; Amami et al, 2015). Increased STN activity was observed during all “stop” trials, whereas increased activity in the arkypallidal (“arky”) neurons of the GPe only occurred during successful “stop” trials This suggests that the STN provides fast “stop” signals to the substantia nigra pars reticulata (SNr), which arrive prior to signals from the striatum that indicate appropriate stop-action behavior. We evaluated the effect of GPi-DBS on inhibitory control in PD patients
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