20Hz beta stimulation of the subthalamic nucleus improves response inhibition in Parkinson’s disease

High-frequency deep brain stimulation of the subthalamic nucleus is used to treat motor symptoms in patients with Parkinson's disease. There is evidence that low-frequency stimulation in the range of 4-10 Hz may improve cognitive functions. This study investigates whether low-frequency deep brain stimulation of the subthalamic nucleus in the beta band (20 Hz) frequency can improve response inhibition in patients with Parkinson's disease. In a double-blinded crossover design, [N=17] participants with Parkinson's disease performed four neuropsychological experiments, while on their usual dopaminergic medication, under no-, standard high-frequency- and 20Hz beta low-frequency deep brain stimulation. The experiments consisted of a response selection task (response execution), a flanker task (conflict monitoring), a Go-NoGo task (automatic inhibition), and a stop-change task (controlled inhibition). Reaction time and response accuracy were analyzed using Bayesian mixed-effect models. Participants responded [m = 33.6 ms, BF = 129.6] slower and [m = 6.0% ms, BF > 1000] more accurately under low-frequency- than high-frequency stimulation, but not under no stimulation during the response selection task. In the Flanker task, participants responded slower under low-frequency- than high-frequency stimulation [m = 77.0 ms, BF > 1000] but not under no stimulation [m = 18.3 ms, BF = 0.1]. We found no performance differences by stimulation condition of the Congruency effect. In the Go-NoGo task, we found low-frequency stimulation slowed responses on uncertain Go trials compared to no stimulation [m = 136.8 ms, BF = 30.3] and high-frequency stimulation [m = 105.2 ms, BF = 2.5]. Additionally, participants committed fewer errors under low-frequency stimulation than under no- and high-frequency stimulation, suggesting that 20Hz subthalamic nucleus stimulation may improve automatic inhibition. Lastly, in the stop-change task, we found no performance modulation by low-frequency stimulation compared to under no- and high-frequency stimulation. Our results show that low-frequency beta stimulation may improve aspects of automatic response inhibition in patients with Parkinson's disease.