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Task-dependent intracortical inhibition is impaired in focal hand dystonia

Authors

  • Cathrin M. Bütefisch MD,

    1. Human Motor Control Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, USA
    2. Neurologisches Therapiecentrum, Institut an der Universität Düsseldorf, Düsseldorf, Germany
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  • Babak Boroojerdi MD,

    1. Human Motor Control Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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  • Robert Chen MBB Chir, FRCPC,

    1. Human Motor Control Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, USA
    2. Division of Neurology, Toronto Western Hospital, University Health Network, University of Toronto, Ontario, Canada
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  • Fortunato Battaglia MD,

    1. Human Motor Control Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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  • Mark Hallett MD

    Corresponding author
    1. Human Motor Control Section, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, USA
    • Human Motor Control Section, NINDS, National Institutes Health, Building 10, Room 5N226, 10 Center Drive, MSC1428, Bethesda, MD 20892-1428
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Abstract

We tested whether task-dependent modulation of inhibition within the motor cortex is impaired in patients with dystonia. Paired-pulse transcranial magnetic stimulation (TMS) at an interstimulus interval of 2 msec was used to measure the effect of two different tasks on short ISI intracortical inhibition (SICI) in dystonic and normal subjects. In two experiments, SICI of the fourth dorsal interosseus (4DIO) and abductor pollicis brevis (APB) muscles were measured before and at the end of the training task. In the first experiment, subjects performed a nonselective task consisting of abducting the thumb, where the APB acted as agonist and the 4DIO as synergist. In the second experiment, the function of the 4DIO was changed as the subjects were asked to consciously inhibit this muscle while abducting the thumb (selective task). Therefore, while the APB was activated in both tasks, the 4DIO was activated in the nonselective task but was in the inhibitory surround in the selective task. We found that performance of the selective but not the nonselective task resulted in increased SICI in the 4DIO of normal but not in dystonic subjects. We conclude that task-dependent SICI is disturbed in patients with dystonia. © 2005 Movement Disorder Society

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