Electrophysiological correlates of proactive control and binding processes during task switching in Tourette syndrome.

The occurrence of tics in Tourette syndrome (TS) has often been linked to impaired cognitive control, but empirical findings are still inconclusive. A recent view proposes that tics may be the result of an abnormally strong interrelation between perceptual processes and motor actions, commonly referred to as perception-action binding. The general aim of the present study was to examine proactive control and binding effects in the context of task switching in adult human patients with TS and matched healthy controls. A cued task switching paradigm was employed in 24 patients (18 male, 6 female) and 25 controls while recording electroencephalography (EEG). Residue iteration decomposition (RIDE) was applied to analyze cue-locked proactive cognitive control and target-locked binding processes. Behavioral task switching performance was unaltered in patients with TS. A cue-locked parietal switch positivity, reflecting proactive control processes involved in the reconfiguration of the new task did not differ between groups. Importantly, target-locked fronto-central (N2) and parietal (P3) modulations, reflecting binding processes between perception and action, differed between groups. Underlying neurophysiological processes were best depicted after temporal decomposition of the EEG signal. The present results argue for unaltered proactive control but altered perception-action binding processes in the context of task switching, supporting the view that the integration of perception and action is processed differently in patients TS. Future studies should further investigate the specific conditions under which binding may be altered in TS and the influence of top-down processes, such as proactive control, on bindings. Significance statement The origin of tics in Tourette syndrome is still poorly understood. Based on the phenomenon of the premonitory urge, it has recently been proposed that tics may be the result of an abnormally strong interrelation between perceptual processes and motor actions, i.e., increased perception-action binding. In the present study, we investigated binding effects in the context of a task switching paradigm using EEG to determine underlying neurophysiological mechanisms. Our results suggest that fronto-central (N2) and parietal (P3) activity are differentially modulated by binding between perception and action in patients with Tourette syndrome, supporting the view that the integration of perception and action is processed differently and may relate to the core symptoms of the disorder, urges and tics.