Altered electrophysiological correlates of motor inhibition and performance monitoring in Tourette's syndrome

Objective: Whether motor inhibition capabilities are impaired in Tourette's syndrome (TS) remains inconclusive. The ability to suppress tics has been proposed to ensure normal motor control in uncomplicated, adult patients. The aim of the present study was to characterize cortical processes of motor inhibition and performance monitoring using event-related potentials (ERPs) elicited by a visual stop signal task. Methods: 15 TS patients and 15 matched healthy controls performed a stop signal task while multi-channel EEG were recorded. Results: The behavioral results revealed no significant differences in inhibitory capabilities between groups. The latency of the P3 was discriminative of inhibition success, with shorter latencies for successful inhibition in both groups. P3 amplitude was not altered by inhibition success, but significantly attenuated for TS patients. Furthermore, the amplitude of the error-related negativity (ERN) was elevated while the error positivity (PE) was diminished for TS patients. Conclusion: In the stop signal task performance is not altered in adult TS patients but ERPs related to motor inhibition and performance monitoring are altered suggesting potential compensatory mechanisms. Significance: The results support the hypothesis of compensatory cortical mechanisms to ensure sufficient motor performance. (C) 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.