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Influence of interhemispheric interactions on motor function in chronic stroke

Authors

  • Nagako Murase MD, PhD,

    1. Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
    2. Department of Neurology, Tokushima University Faculty of Medicine, Tokushima, Japan
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  • Julie Duque BS,

    1. Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
    2. Laboratory of Neurophysiology, University of Louvain, Brussels, Belgium
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  • Riccardo Mazzocchio MD,

    1. Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
    2. Neurophysiologic Clinic Section, Department of Neurological Sciences, University of Siena, Siena, Italy
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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, NINDS, NIH, Bethesda, MD 20817
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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

In patients with chronic stroke, the primary motor cortex of the intact hemisphere (M1intact hemisphere) may influence functional recovery, possibly through transcallosal effects exerted over M1 in the lesioned hemisphere (M1lesioned hemisphere). Here, we studied interhemispheric inhibition (IHI) between M1intact hemisphere and M1lesioned hemisphere in the process of generation of a voluntary movement by the paretic hand in patients with chronic subcortical stroke and in healthy volunteers. IHI was evaluated in both hands preceding the onset of unilateral voluntary index finger movements (paretic hand in patients, right hand in controls) in a simple reaction time paradigm. IHI at rest and shortly after the Go signal were comparable in patients and controls. Closer to movement onset, IHI targeting the moving index finger turned into facilitation in controls but remained deep in patients, a finding that correlated with poor motor performance. These results document an abnormally high interhemispheric inhibitory drive from M1intact hemisphere to M1lesioned hemisphere in the process of generation of a voluntary movement by the paretic hand. It is conceivable that this abnormality could adversely influence motor recovery in some patients with subcortical stroke, an interpretation consistent with models of interhemispheric competition in motor and sensory systems.

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