Stretch reflex augmentation by subthreshold TMS is evidence for corticospinal signal integration

A.C. Schouten, M.J.L. Perenboom, M. van de Ruit, J.H. de Groot, C.G.M. Meskers

    Research output: Contribution to conferencePosterAcademic

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    Abstract

    Reflex adaptation to environment and task at hand plays a key role in motor control. In search for cortical reflex modulation mechanisms, transcranial magnetic stimulation (TMS) has been found to augment muscle stretch reflexes as recorded by electromyography (EMG). However, instead of reflecting true integration of efferent sensory with cortical activity, this augmentation can alternatively be explained by spinal summation of the stretch response with TMS induced motor evoked potentials (MEP). The goal of this study was to confirm true peripheral-cortical signal integration by combining muscle reflex responses with timed subthreshold TMS.
    Mechanically induced ramp-and-hold stretches (duration: 40 ms, velocity: 1.5 rad/s) of the m. flexor carpi radialis were combined with TMS pulses at 96% of active motor threshold applied between 10 ms before and 120 ms after stretch onset with a resolution of 5 to 10 ms. Significant MEP like augmentation of the EMG response was found when TMS was timed to arrive between 60 and 90 ms after stretch onset with a consistent and short delay between estimated TMS arrival time and peak EMG activity of 5 to 10 ms. Timing and nature of muscle stretch reflex activity augmentation by subthreshold TMS reflect supraspinal integration of peripheral sensory afferent with cortical efferent signals as a mechanism of supraspinal reflex adaptation.
    Original languageEnglish
    Number of pages1
    Publication statusPublished - 13 Nov 2013
    EventSociety for Neuroscience Annual Meeting, Neuroscience 2013 - San Diego, United States
    Duration: 9 Nov 201313 Nov 2013

    Conference

    ConferenceSociety for Neuroscience Annual Meeting, Neuroscience 2013
    Abbreviated titleNeuroscience 2013
    CountryUnited States
    CitySan Diego
    Period9/11/1313/11/13

    Keywords

    • Reflex
    • TMS
    • Motor control

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