Modulatory Effects of Transcranial Direct Current Stimulation on Laser-Evoked Potentials

Authors

  • Gabor Csifcsak MD,

    1. Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany;
    2. Department of Psychiatry, University of Szeged, Semmelweis u. 6, 6725 Szeged, Hungary;
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  • Andrea Antal PhD,

    1. Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany;
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  • Ferdinand Hillers,

    1. Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany;
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  • Maik Levold,

    1. Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany;
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  • Cornelius G. Bachmann MD,

    1. Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany;
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  • Svenja Happe MD,

    1. Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany;
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  • Michael A. Nitsche MD,

    1. Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany;
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  • Jens Ellrich MD,

    1. Department of Health Science and Technology, Center for Sensory-Motor Interaction SMI, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7D2, DK-9220 Aalborg
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  • Walter Paulus MD

    1. Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany;
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  • Original Research Articles

Andrea Antal, PhD, Department of Clinical Neurophysiology, Georg-August University of Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany. Tel: 49-551-398461; Fax: 49-551-398126; E-mail: AAntal@gwdg.de.

ABSTRACT

Objective.  Invasive stimulation of the motor cortex has been used for years to alleviate chronic intractable pain in humans. In our study, we have investigated the effect of transcranial direct current stimulation (tDCS), a noninvasive stimulation method, for manipulating the excitability of cortical motor areas on laser evoked potentials (LEP) and acute pain perception.

Designs and Settings.  The amplitude of the N1, N2, and P2 LEP components of 10 healthy volunteers were evaluated prior to and following anodal, cathodal, and sham stimulation of the primary motor cortex. In a separate experiment subjective, pain rating scores of 16 healthy subjects in two perceptual categories (warm sensation, mild pain) were also analyzed.

Results.  Cathodal tDCS significantly reduced the amplitude of N2 and P2 components compared with anodal or sham stimulation. However, neither of the tDCS types modified significantly the laser energy values necessary to induce moderate pain. In a separate experiment, cathodal stimulation significantly diminished mild pain sensation only when laser-stimulating the hand contralateral to the side of tDCS, while anodal stimulation modified warm sensation.

Conclusions.  The possible underlying mechanisms of our findings in view of recent neuroimaging studies are discussed. To our knowledge this study is the first to demonstrate the mild antinociceptive effect of tDCS over the primary motor cortex in healthy volunteers.

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