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Contribution of the ipsilateral motor cortex to recovery after chronic stroke

Authors

  • Konrad J. Werhahn MD,

    1. Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
    Current affiliation:
    1. Department of Neurology, University of Mainz, Rhineland-Palatinate, Germany
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  • Adriana B. Conforto MD,

    1. Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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  • Nadja Kadom MD,

    1. Neuroimmunology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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  • Mark Hallett MD,

    1. Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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  • Leonardo G. Cohen MD

    Corresponding author
    1. Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
    • Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 5N226, 10 Center Drive, Bethesda, MD 20892-1428
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  • This article is a US Government work and, as such, is in the public domain in the United States of America.

Abstract

It has been proposed that the intact (ipsilateral) motor cortex play a significant role mediating recovery of motor function in the paretic hand of chronic stroke patients, but this hypothesis has not been tested experimentally. Here, we evaluated the effects of transcranial magnetic stimulation (TMS) on motor performance of the paretic hand of chronic stroke patients and healthy controls. We hypothesized that, if activity in the intact hemisphere contributes to functional recovery, TMS should result in abnormal motor behavior in the paretic hand. We found that stimulation of the intact hemisphere resulted in delayed simple reaction times (RTs) in the contralateral healthy but not in the ipsilateral paretic hand, whereas stimulation of the lesioned hemisphere led to a marked delay in RT in the contralateral paretic hand but not in the ipsilateral healthy hand. RT delays in the paretic hand correlated well with functional recovery. Finger tapping in the paretic hand was affected by TMS of the lesioned but not the intact hemisphere. These results are consistent with the idea that recovered motor function in the paretic hand of chronic stroke patients relies predominantly on reorganized activity within motor areas of the affected hemisphere.

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