Epicranial Direct Current Stimulation Suppresses Harmaline Tremor in Rats

  • Author Footnotes
    a Indicates equal contribution.
    Ahmad Khatoun
    a Indicates equal contribution.
    Experimental Oto-, Rhino-, Laryngology, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium

    The Leuven Brain Institute, Katholieke Universiteit Leuven, Leuven, Belgium
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  • Author Footnotes
    a Indicates equal contribution.
    Boateng Asamoah
    a Indicates equal contribution.
    Experimental Oto-, Rhino-, Laryngology, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium

    The Leuven Brain Institute, Katholieke Universiteit Leuven, Leuven, Belgium
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  • Alexandra Boogers
    Experimental Oto-, Rhino-, Laryngology, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium

    The Leuven Brain Institute, Katholieke Universiteit Leuven, Leuven, Belgium
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  • Myles Mc Laughlin
    Address correspondence to: Myles Mc Laughlin, PhD, MSc, Experimental Oto-, Rhino-, Laryngology, Department of Neurosciences, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium.
    Experimental Oto-, Rhino-, Laryngology, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium

    The Leuven Brain Institute, Katholieke Universiteit Leuven, Leuven, Belgium
    Search for articles by this author
  • Author Footnotes
    a Indicates equal contribution.
Published:September 15, 2022DOI:



      Essential tremor (ET) is the most common neurologic movement disorder worldwide. It is characterized by a postural tremor, mostly in the upper extremities, causing difficulties in daily activities that may lead to social exclusion. Some patients with ET do not respond well to or do not tolerate medication. Thus, deep brain stimulation can be offered. In a recent study, we proposed a novel neuromodulation technique called epicranial current stimulation (ECS) that works in a minimally invasive way by placing the electrodes subcutaneously under the skin and directly over the skull. In this study, we investigated the feasibility of using epicranial direct current stimulation (EDCS) to suppress tremor in a rat harmaline ET model.

      Materials and Methods

      In experiment 1, seven Sprague Dawley rats were implanted with ECS electrodes placed over the motor cortex (MC) and the cerebellum to investigate whether stimulating between them could suppress tremor. In experiments 2 and 3, eight rats were implanted with ECS electrodes placed over the MC, cerebellum, and the rostral skull to separate the effects on tremor caused by stimulating each target. During each experiment, the rats were injected with harmaline, which induced tremor that was quantified using an accelerometer. EDCS was then applied through the different electrode configurations to evaluate their tremor suppression effectiveness.


      Results from experiment 1 showed that MCcathode-Cerebellaranode suppressed tremor compared with stimulation-OFF but MCanode-Cerebellarcathode did not. Furthermore, experiments 2 and 3 showed that it was the cerebellar anodal electrode that was driving tremor suppression.


      Cerebellar EDCS suppressed harmaline tremor in rats in a polarity-dependent manner. EDCS could be a promising neuromodulation method for patients with ET.


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