Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation
- City College of the City University of New York, United States
- New York University School of Medicine, United States
- 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
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.
Reviewing Editor
- Richard Ivry, University of California, Berkeley, United States
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.
Version history
- Received: June 16, 2016
- Accepted: February 6, 2017
- Accepted Manuscript published: February 7, 2017 (version 1)
- Version of Record published: March 28, 2017 (version 2)
- 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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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
Further reading
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Mechanosensory neurons located across the body surface respond to tactile stimuli and elicit diverse behavioral responses, from relatively simple stimulus location-aimed movements to complex movement sequences. How mechanosensory neurons and their postsynaptic circuits influence such diverse behaviors remains unclear. We previously discovered that Drosophila perform a body location-prioritized grooming sequence when mechanosensory neurons at different locations on the head and body are simultaneously stimulated by dust (Hampel et al., 2017; Seeds et al., 2014). Here, we identify nearly all mechanosensory neurons on the Drosophila head that individually elicit aimed grooming of specific head locations, while collectively eliciting a whole head grooming sequence. Different tracing methods were used to reconstruct the projections of these neurons from different locations on the head to their distinct arborizations in the brain. This provides the first synaptic resolution somatotopic map of a head, and defines the parallel-projecting mechanosensory pathways that elicit head grooming.
