Comparative Study of a Continuous Train of Theta-Burst Stimulation for a Duration of 20 s (cTBS 300) versus a Duration of 40 s (cTBS 600) in a Pre-Stimulation Relaxed Condition in Healthy Volunteers

Jan Haeckert; John Rothwell; Ricci Hannah; Alkomiet Hasan; Wolfgang Strube

doi:10.3390/brainsci11060737

Comparative Study of a Continuous Train of Theta-Burst Stimulation for a Duration of 20 s (cTBS 300) versus a Duration of 40 s (cTBS 600) in a Pre-Stimulation Relaxed Condition in Healthy Volunteers

Brain Sci. 2021 Jun 1;11(6):737. doi: 10.3390/brainsci11060737.

Authors

Jan Haeckert¹, John Rothwell², Ricci Hannah³, Alkomiet Hasan^{1

4}, Wolfgang Strube^{1

4}

Affiliations

¹ Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty, University of Augsburg, BKH Augsburg, Dr.-Mack-Str. 1, 86156 Augsburg, Germany.
² Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
³ Department of Psychology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
⁴ Department of Psychiatry and Psychotherapy, University Hospital Munich, LMU Munich, Nußbaumstraße 7, 80336 München, Germany.

Abstract

As variable after effects have been observed following phasic muscle contraction prior to continuous theta-burst stimulation (cTBS), we here investigated two cTBS protocols (cTBS300 and cTBS600) in 20 healthy participants employing a pre-relaxed muscle condition including visual feedback on idle peripheral surface EMG activity. Furthermore, we assessed corticospinal excitability measures also from a pre-relaxed state to better understand the potential impact of these proposed contributors to TBS. Motor-evoked potential (MEP) magnitude changes were assessed for 30 min. The linear model computed across both experimental paradigms (cTBS300 and cTBS600) revealed a main effect of TIME COURSE (p = 0.044). Separate exploratory analysis for cTBS300 revealed a main effect of TIME COURSE (p = 0.031), which did not maintain significance after Greenhouse-Geisser correction (p = 0.073). For cTBS600, no main effects were observed. An exploratory analysis revealed a correlation between relative SICF at 2.0 ms (p = 0.006) and after effects (relative mean change) of cTBS600, which did not survive correction for multiple testing. Our findings thereby do not support the hypothesis of a specific excitability modulating effect of cTBS applied to the human motor-cortex in setups with pre-relaxed muscle conditions.

Keywords: cTBS 300 versus cTBS 600; continuous theta burst stimulation (cTBS); healthy participants; non-invasive brain stimulation; pre-relaxed muscle condition.