2026 ECNP Congress

PS03-3049

Pre-stimulation corticomuscular coherence as a candidate marker of responsiveness to individualised beta-frequency continuous theta burst stimulation

Daisuke Kudo — M. Nito, A. Kikuchi, S. Tanabe, T. Yamaguchi · Yamagata Prefectural University of Health Sciences, Department of Physical Therapy, Yamagata- Yamagata, Japan

2026 ECNP Congress

Introduction

Theta burst stimulation (TBS) is a non-invasive brain stimulation protocol used to modulate corticospinal excitability when applied over the primary motor cortex [1]. However, TBS-induced changes in motor-evoked potentials (MEPs) show substantial inter-individual variability [2]. A recent study reported that intermittent TBS using individualized beta-band frequencies (15–35 Hz) derived from corticomuscular coherence (CMC) enhanced facilitatory effects on corticospinal excitability [3]. Whether the same frequency-individualization strategy can be applied to continuous TBS (cTBS), which is generally expected to suppress corticospinal excitability, remains unclear. This study examined whether CMC-guided individualized beta-frequency cTBS induces immediate MEP suppression and whether pre-stimulation CMC peak magnitude is associated with the magnitude of MEP change.

Methods

Eighteen healthy participants (23 ± 4 years; ten women) completed three stimulation sessions in a randomized order on separate days: individualized cTBS, conventional cTBS, and sham cTBS. Stimulation was applied over the hand representation of the left primary motor cortex. For the individualized condition, the conventional 50-Hz intraburst frequency of cTBS was replaced with each participant’s peak beta-band CMC frequency. CMC was measured during weak isometric contraction using EEG recorded at C3 and a site 2 cm anterior to C3, together with electromyography from the first dorsal interosseous (FDI) muscle. MEP amplitudes from the FDI muscle were assessed before (Pre) and immediately after stimulation (Post0). The Post0/Pre MEP ratio was compared across conditions using a linear mixed model with stimulation condition as a fixed effect and participant as a random effect. Post hoc pairwise comparisons with Bonferroni correction were performed when a significant main effect was detected. Pearson’s correlation coefficients were calculated to assess associations between pre-stimulation CMC peak magnitude and the Post0/Pre MEP ratio for each condition.

Results

A significant main effect of stimulation condition was observed for the Post0/Pre MEP ratio [F(2, 34) = 6.0, p < 0.01]. Post hoc analysis showed that the ratio was significantly lower in the individualized cTBS condition than in the sham condition (p < 0.05). No significant difference was reported between the individualized and conventional cTBS conditions. In the individualized cTBS condition, pre-stimulation CMC peak magnitude was positively correlated with the Post0/Pre MEP ratio (r = 0.71, p < 0.01), indicating that lower pre-stimulation CMC peak magnitude was associated with greater MEP suppression. No significant correlations were observed in the conventional cTBS or sham cTBS condition.

Conclusions

Individualized beta-frequency cTBS induced greater immediate MEP suppression than sham stimulation in healthy individuals. In addition, pre-stimulation CMC peak magnitude was associated with the magnitude of MEP suppression only in the individualized cTBS condition. These findings suggest that the pre-stimulation neurophysiological state indexed by CMC may help estimate responsiveness to frequency-individualized cTBS. Further studies with larger samples and longer follow-up assessments are needed to determine whether this association predicts longer-lasting MEP changes after individualized cTBS.

References

  1. Huang, Y.Z., Edwards, M.J., Rounis, E., Bhatia, K.P., Rothwell, J.C., 2005. Theta burst stimulation of the human motor cortex. Neuron 45 (2), 201-206.
  2. Corp, D.T., Bereznicki, H.G.K., Clark, G.M., Youssef, G.J., Fried, P.J., Jannati, A., Davies, C.B., Gomes-Osman, J., Stamm, J., Chung, S.W., Bowe, S.J., Rogasch, N.C., Fitzgerald, P.B., Koch, G., Di Lazzaro, V., Pascual-Leone, A., Enticott, P.G., Big TMS Data Collaboration, 2020. Large-scale analysis of interindividual variability in theta-burst stimulation data: results from the Big TMS Data Collaboration. Brain Stimul. 13 (5), 1476-1488.
  3. Kudo, D., Nito, M., Kikuchi, A., Tanabe, S., Yamaguchi, T., 2026. Individualized beta frequency intermittent theta burst stimulation enhances corticospinal plasticity in healthy adults. Neuromodulation 29 (2), 298-305.