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Randomized Controlled Trial
. 2019 Dec;597(23):5671-5686.
doi: 10.1113/JP278638. Epub 2019 Nov 2.

Phase of sensorimotor μ-oscillation modulates cortical responses to transcranial magnetic stimulation of the human motor cortex

Debora Desideri  1 , Christoph Zrenner  1 , Ulf Ziemann  1 , Paolo Belardinelli  1
Affiliations
Free article
Randomized Controlled Trial

Phase of sensorimotor μ-oscillation modulates cortical responses to transcranial magnetic stimulation of the human motor cortex

Debora Desideri et al. J Physiol. 2019 Dec.
Free article

Abstract

Key points: Oscillatory brain activity coordinates the response of cortical neurons to synaptic inputs in a phase-dependent manner. Larger motor-evoked responses are obtained in a hand muscle when transcranial magnetic stimulation (TMS) is synchronized to the phase of the sensorimotor μ-rhythm. In this study we further showed that TMS applied at the negative vs. positive peak of the μ-rhythm is associated with higher absolute amplitude of the evoked EEG potential at 100 ms after stimulation. This demonstrates that cortical responses are sensitive to excitability fluctuation with brain oscillations Our results indicate that brain state-dependent stimulation is a new useful technique for the investigation of stimulus-related cortical dynamics.

Abstract: Oscillatory brain activity coordinates the response of cortical neurons to synaptic inputs in a phase-dependent manner. Transcranial magnetic stimulation (TMS) of the human primary motor cortex elicits larger motor-evoked potentials (MEPs) when applied at the negative vs. positive peak of the sensorimotor μ-rhythm recorded with EEG, demonstrating that this phase represents a state of higher excitability of the cortico-spinal system. Here, we investigated the influence of the phase of the μ-rhythm on cortical responses to TMS as measured by EEG. We tested different stimulation intensities above and below resting motor threshold (RMT), and a realistic sham TMS condition. TMS at 110% RMT applied at the negative vs. positive peak of the μ-rhythm was associated with higher absolute amplitudes of TMS-evoked potentials at 70 ms (P70) and 100 ms (N100). Enhancement of the N100 was confirmed with negative peak-triggered 90% RMT TMS, while phase of the μ-rhythm did not influence evoked responses elicited by sham TMS. These findings extend the idea that TMS applied at the negative vs. positive peak of the endogenous μ-oscillation recruits a larger portion of neurons as a function of stimulation intensity. This further corroborates that brain oscillations determine fluctuations in cortical excitability and establishes phase-triggered EEG-TMS as a sensitive tool to investigate the effects of brain oscillations on stimulus-related cortical dynamics.

Keywords: EEG-TMS; TMS-evoked EEG potentials; brain oscillations; cortical excitability; motor cortex.

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References

    1. Başar E & Dumermuth G (1982). EEG-brain dynamics: relation between EEG and brain evoked potentials. Comp Program Biomed 14, 227-228.
    1. Bender S, Basseler K, Sebastian I, Resch F, Kammer T, Oelkers-Ax R & Weisbrod M (2005). Electroencephalographic response to transcranial magnetic stimulation in children: evidence for giant inhibitory potentials. Ann Neurol 58, 58-67.
    1. Bergmann TO, Molle M, Schmidt MA, Lindner C, Marshall L, Born J & Siebner HR (2012). EEG-guided transcranial magnetic stimulation reveals rapid shifts in motor cortical excitability during the human sleep slow oscillation. J Neurosci 32, 243-253.
    1. Bonato C, Miniussi C & Rossini PM (2006). Transcranial magnetic stimulation and cortical evoked potentials: a TMS/EEG co-registration study. Clin Neurophysiol 117, 1699-1707.
    1. Bonnard M, Spieser L, Meziane HB, de Graaf JB & Pailhous J (2009). Prior intention can locally tune inhibitory processes in the primary motor cortex: direct evidence from combined TMS-EEG. Eur J Neurosci 30, 913-923.

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