title: Spatiotemporal structure of intracranial electric fields induced by transcranial electric stimulation in humans and nonhuman primates.
abstract: Transcranial electric stimulation (TES) is an emerging technique, developed to non-invasively modulate brain function. However, the spatiotemporal distribution of the intracranial electric fields induced by TES remains poorly understood. In particular, it is unclear how much current actually reaches the brain, and how it distributes across the brain. Lack of this basic information precludes a firm mechanistic understanding of TES effects. In this study we directly measure the spatial and temporal characteristics of the electric field generated by TES using stereotactic EEG (s-EEG) electrode arrays implanted in cebus monkeys and surgical epilepsy patients. We found a small frequency dependent decrease (10%) in magnitudes of TES induced potentials and negligible phase shifts over space. Electric field strengths were strongest in superficial brain regions with maximum values of about 0.5 mV/mm. Our results provide crucial information of the underlying biophysics in TES applications in humans and the optimization and design of TES stimulation protocols. In addition, our findings have broad implications concerning electric field propagation in non-invasive recording techniques such as EEG/MEG.
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA.|Center for the Developing Brain, Child Mind Institute, New York, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Opitz
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Falchier
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA.|Key Laboratory of Behavioral Science and Magnetic Resonance Imaging Research Center, Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Chao-Gan
authors.initials: CG
authors.lastname: Yan
authors.affiliation: Department of Neurosurgery, Hofstra Northwell School of Medicine, and Feinstein Institute for Medical Research, Manhasset, NY, USA.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Yeagle
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA.|Department of Psychiatry, NYU Langone School of Medicine, NY, USA.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Linn
authors.affiliation: Department of Neurosurgery, Hofstra Northwell School of Medicine, and Feinstein Institute for Medical Research, Manhasset, NY, USA.
authors.forename: Pierre
authors.initials: P
authors.lastname: Megevand
authors.affiliation: Danish Research Center for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark.|Max Planck Institute for Biological Cybernetics, Tübingen, Germany.|Department of Electrical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark.
authors.forename: Axel
authors.initials: A
authors.lastname: Thielscher
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA.
authors.forename: Ross
authors.initials: R
authors.lastname: Deborah A
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA.|Center for the Developing Brain, Child Mind Institute, New York, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Milham
authors.affiliation: Department of Neurosurgery, Hofstra Northwell School of Medicine, and Feinstein Institute for Medical Research, Manhasset, NY, USA.
authors.forename: Ashesh D
authors.initials: AD
authors.lastname: Mehta
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA.|Departments of Neurological Surgery and Psychiatry, Columbia University College of Physicians and Surgeons, New York, USA.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Schroeder
mesh_terms: D000328:Adult; D000818:Animals; D001921:Brain / Q000502:physiology*; D002428:Cebus; D004569:Electroencephalography / Q000295:instrumentation*; D004827:Epilepsy / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D062211:Spatio-Temporal Analysis; D065908:Transcranial Direct Current Stimulation / Q000295:instrumentation*