EEG-triggered TMS reveals stronger brain state-dependent modulation of motor evoked potentials at weaker stimulation intensities

Brain Stimulation

卷:12

Jochen Triesch¹  Ulf Ziemann²  Christoph Zrenner³  Natalie Schaworonkow³ 

[1] Department of Neurology &

[2] Stroke, and Hertie Institute for Clinical Brain Research, University of Tübingen, Germany;

[3] Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe University, Frankfurt am Main, Germany;

关键词: EEG-TMS;    Brain-state dependent brain-stimulation;    Sensorimotor μ-rhythm;    Corticospinal excitability;    Motor evoked potential;    Input-output curve;   

DOI  :  

来源: DOAJ

【 摘 要 】

Background: Corticospinal excitability depends on the current brain state. The recent development of real-time EEG-triggered transcranial magnetic stimulation (EEG-TMS) allows studying this relationship in a causal fashion. Specifically, it has been shown that corticospinal excitability is higher during the scalp surface negative EEG peak compared to the positive peak of μ-oscillations in sensorimotor cortex, as indexed by larger motor evoked potentials (MEPs) for fixed stimulation intensity. Objective: We further characterize the effect of μ-rhythm phase on the MEP input-output (IO) curve by measuring the degree of excitability modulation across a range of stimulation intensities. We furthermore seek to optimize stimulation parameters to enable discrimination of functionally relevant EEG-defined brain states. Methods: A real-time EEG-TMS system was used to trigger MEPs during instantaneous brain-states corresponding to μ-rhythm surface positive and negative peaks with five different stimulation intensities covering an individually calibrated MEP IO curve in 15 healthy participants. Results: MEP amplitude is modulated by μ-phase across a wide range of stimulation intensities, with larger MEPs at the surface negative peak. The largest relative MEP-modulation was observed for weak intensities, the largest absolute MEP-modulation for intermediate intensities. These results indicate a leftward shift of the MEP IO curve during the μ-rhythm negative peak. Conclusion: The choice of stimulation intensity influences the observed degree of corticospinal excitability modulation by μ-phase. Lower stimulation intensities enable more efficient differentiation of EEG μ-phase-defined brain states.

【 授权许可】

Unknown