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Induction of LTD-like corticospinal plasticity by low-frequency rTMS depends on pre-stimulus phase of sensorimotor mu-rhythm
Journal article   Open access   Peer reviewed

Induction of LTD-like corticospinal plasticity by low-frequency rTMS depends on pre-stimulus phase of sensorimotor mu-rhythm

David Baur, Dragana Galevska, Sara Hussain, Leonardo G. Cohen, Ulf Ziemann and Christoph Zrenner
Brain stimulation, Vol.13(6), pp.1580-1587
11/01/2020
DOI: 10.1016/j.brs.2020.09.005
PMCID: PMC7710977
PMID: 32949780
url
https://doi.org/10.1016/j.brs.2020.09.005View
Published (Version of record) Open Access

Abstract

Background: Neural oscillations reflect rapidly changing brain excitability states. We have demonstrated previously with EEG-triggered transcranial magnetic stimulation (TMS) of human motor cortex that the positive vs. negative peak of the sensorimotor tt-oscillation reflect corticospinal low-vs. high-excitability states. In vitro experiments showed that induction of long-term depression (LTD) by low-frequency stimulation depends on the postsynaptic excitability state. Objective/Hypothesis: We tested the hypothesis that induction of LTD-like corticospinal plasticity in humans by 1 Hz repetitive TMS (rTMS) is enhanced when rTMS is synchronized with the low-excitability state, but decreased or even shifted towards long-term (LTP)-like plasticity when synchronized with the high-excitability state. Methods: We applied real-time EEG-triggered 1-Hz-rTMS (900 pulses) to the hand area of motor cortex in healthy subjects. In a randomized double-blind three-condition crossover design, pulses were synchronized to either the positive or negative peak of the sensorimotor mu-oscillation, or were applied at random phase (control). The amplitude of motor evoked potentials was recorded as an index of corticospinal excitability before and after 1-Hz-rTMS. Results: 1-Hz-rTMS at random phase resulted in a trend towards LTD-like corticospinal plasticity. RTMS in the positive peak condition (i.e., the low-excitability state) induced significant LTD-like plasticity. RTMS in the negative peak condition (i.e., the high-excitability state) showed a trend towards LTP-like plasticity, which was significantly different from the other two conditions. Conclusion: The level of corticospinal depolarization reflected by phase of the mu-oscillation determines the degree of corticospinal plasticity induced by low-frequency rTMS, a finding that may guide future personalized therapeutic stimulation. (C) 2020 The Author(s). Published by Elsevier Inc.
Clinical Neurology Life Sciences & Biomedicine Neurosciences Neurosciences & Neurology Science & Technology

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