Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

  1. Yu Huang
  2. Anli A Liu  Is a corresponding author
  3. Belen Lafon
  4. Daniel Friedman
  5. Michael Dayan
  6. Xiuyuan Wang
  7. Marom Bikson
  8. Werner K Doyle
  9. Orrin Devinsky
  10. Lucas C Parra  Is a corresponding author
  1. City College of the City University of New York, United States
  2. New York University School of Medicine, United States
  3. Mayo Clinic, United States

Abstract

Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimate electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.4 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r=0.89) and depth (r=0.84) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials.

Article and author information

Author details

  1. Yu Huang

    Department of Biomedical Engineering, City College of the City University of New York, New York, United States
    Competing interests
    No competing interests declared.
  2. Anli A Liu

    Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
    For correspondence
    anli.liu@nyumc.org
    Competing interests
    No competing interests declared.
  3. Belen Lafon

    Department of Biomedical Engineering, City College of the City University of New York, New York, United States
    Competing interests
    No competing interests declared.
  4. Daniel Friedman

    Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
    Competing interests
    No competing interests declared.
  5. Michael Dayan

    Department of Neurology, Mayo Clinic, Rochester, United States
    Competing interests
    No competing interests declared.
  6. Xiuyuan Wang

    Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
    Competing interests
    No competing interests declared.
  7. Marom Bikson

    Department of Biomedical Engineering, City College of the City University of New York, New York, United States
    Competing interests
    Marom Bikson, Has significant interest in Soterix Medical Inc. which commercializes hardware and software for TES. He is listed as inventors on patents (U.S. Patent application No.13/264,142) related to TES.
  8. Werner K Doyle

    Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
    Competing interests
    No competing interests declared.
  9. Orrin Devinsky

    Comprehensive Epilepsy Center, New York University School of Medicine, New York, United States
    Competing interests
    No competing interests declared.
  10. Lucas C Parra

    Department of Biomedical Engineering, City College of the City University of New York, New York, United States
    For correspondence
    parra@ccny.cuny.edu
    Competing interests
    Lucas C Parra, Has significant interest in Soterix Medical Inc. which commercializes hardware and software for TES. He is listed as inventors on patents (U.S. Patent application No.13/264,142) related to TES.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4667-816X

Funding

National Institute of Neurological Disorders and Stroke

  • Yu Huang
  • Anli A Liu
  • Belen Lafon
  • Daniel Friedman
  • Michael Dayan
  • Xiuyuan Wang
  • Marom Bikson
  • Werner K Doyle
  • Orrin Devinsky
  • Lucas C Parra

National Institute of Mental Health

  • Yu Huang
  • Anli A Liu
  • Belen Lafon
  • Daniel Friedman
  • Michael Dayan
  • Xiuyuan Wang
  • Marom Bikson
  • Werner K Doyle
  • Orrin Devinsky
  • Lucas C Parra

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: This study was performed at the New York University Medical Center (NYUMC). The protocol was approved by the NYUMC Institutional Review Board(IRB) and all patients provided written informed consent prior to their participation in the study. A physician was present at the bedside during the entire procedure to monitor for clinical safety.

Reviewing Editor

  1. Richard Ivry, University of California, Berkeley, United States

Publication history

  1. Received: June 16, 2016
  2. Accepted: February 6, 2017
  3. Accepted Manuscript published: February 7, 2017 (version 1)
  4. Version of Record published: March 28, 2017 (version 2)
  5. Version of Record updated: February 15, 2018 (version 3)

Copyright

© 2017, Huang et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Yu Huang
  2. Anli A Liu
  3. Belen Lafon
  4. Daniel Friedman
  5. Michael Dayan
  6. Xiuyuan Wang
  7. Marom Bikson
  8. Werner K Doyle
  9. Orrin Devinsky
  10. Lucas C Parra
(2017)
Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation
eLife 6:e18834.
https://doi.org/10.7554/eLife.18834

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