Physiological and introspective antecedents of tics and movements in adults with tic disorders

• Published in: Clinical neurophysiology Vol. 151; pp. 143 - 150
• Main Authors: Triggiani, Antonio I., Scheman, Kaya, Pirio Richardson, Sarah, Matsuhashi, Masao, Peckham, Elizabeth, Nahab, Fatta, Mari, Zoltan, Ravindran, Shashi, Hallett, Mark
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.07.2023
• Subjects: Adult; Bereitschaftspotential; Contingent Negative Variation; Electroencephalography; Event-related desynchronization; Humans; Libet’s clock; Movement - physiology; Neurology; Tic; Tic Disorders - diagnosis; Tics; Tourette Syndrome; Event-related desynchronization; Electroencephalography; Libet’s clock; Bereitschaftspotential; Tic; event-related desynchronization; tic
• ISSN: 1388-2457; 1872-8952; 1872-8952
• DOI: 10.1016/j.clinph.2023.03.362

•We replicated Libet’s clock experiment with healthy volunteers and patients with tic disorders.•Despite the Bereitschaftspotential occurring before most patient’s tics, many did not show beta event-related desynchronization.•The dissociation of these correlates of movement may show a motor system both facilitating and suppressing tics. To investigate the subjective phenomenon and the neural underpinnings of tics compared with voluntary movements in patients with tic disorders. We recorded electroencephalographic and electromyographic data while subjects completed a Libet clock paradigm. Patients and healthy volunteers reported the times of W (willing to move) and M (movement occurrence) while performing voluntary movements. This was repeated only for the patients for the tics. In the patients, W and M times preceding voluntary movements and tics did not significantly differ from voluntary movements of healthy volunteers. The Bereitschaftspotentials in the patients were similar to healthy volunteers. Tics were only assessable for 7 patients due to artifacts. Two subjects did not show Bereitschaftspotentials, and they reported the lowest levels of tic voluntariness. 5 subjects did not show beta band event-related desynchronization before tics. For patients, the sense of volition for tics is similar to that of their voluntary movements which is similar to normal. Patients showed dissociations between the Bereitschaftspotential and beta desynchronization for tics, with 5/7 showing normal Bereitschaftspotentials and 2/7 showing desynchronization. The absence of desynchronization may suggest attempts to suppress tics. This physiology shows a difference for most tics compared with normal movements.