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Phase of sensorimotor μ-oscillation modulates cortical responses to TMS of the human motor cortex.
J Physiol 2019JP

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 electroencephalography (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 (TEPs) 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 notion 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. This article is protected by copyright. All rights reserved.

Authors+Show Affiliations

Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany.Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany.Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany.Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31535388

Citation

Desideri, Debora, et al. "Phase of Sensorimotor Μ-oscillation Modulates Cortical Responses to TMS of the Human Motor Cortex." The Journal of Physiology, 2019.
Desideri D, Zrenner C, Ziemann U, et al. Phase of sensorimotor μ-oscillation modulates cortical responses to TMS of the human motor cortex. J Physiol (Lond). 2019.
Desideri, D., Zrenner, C., Ziemann, U., & Belardinelli, P. (2019). Phase of sensorimotor μ-oscillation modulates cortical responses to TMS of the human motor cortex. The Journal of Physiology, doi:10.1113/JP278638.
Desideri D, et al. Phase of Sensorimotor Μ-oscillation Modulates Cortical Responses to TMS of the Human Motor Cortex. J Physiol (Lond). 2019 Sep 19; PubMed PMID: 31535388.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Phase of sensorimotor μ-oscillation modulates cortical responses to TMS of the human motor cortex. AU - Desideri,Debora, AU - Zrenner,Christoph, AU - Ziemann,Ulf, AU - Belardinelli,Paolo, Y1 - 2019/09/19/ PY - 2019/07/18/received PY - 2019/09/17/accepted PY - 2019/9/20/entrez JF - The Journal of physiology JO - J. Physiol. (Lond.) N2 - 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 electroencephalography (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 (TEPs) 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 notion 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. This article is protected by copyright. All rights reserved. SN - 1469-7793 UR - https://www.unboundmedicine.com/medline/citation/31535388/Phase_of_sensorimotor_μ-oscillation_modulates_cortical_responses_to_TMS_of_the_human_motor_cortex L2 - https://doi.org/10.1113/JP278638 DB - PRIME DP - Unbound Medicine ER -