Annals of Biomedical Engineering

, Volume 19, Issue 3, pp 317–328

A theoretical comparison of electric and magnetic stimulation of the brain

Authors

  • Joshua M. Saypol
    • Biomedical Engineering and Instrumentation Program National Center for Research ResourcesNational Institute of Health
  • Bradley J. Roth
    • Biomedical Engineering and Instrumentation Program National Center for Research ResourcesNational Institute of Health
  • Leonardo G. Cohen
    • Human Cortical Physiology Unit Human Motor Control Section Medical Neurology Branch National Institute of Neurological Disorders and StrokeNational Institutes of Health
  • Mark Hallett
    • Human Cortical Physiology Unit Human Motor Control Section Medical Neurology Branch National Institute of Neurological Disorders and StrokeNational Institutes of Health
Article

DOI: 10.1007/BF02584306

Cite this article as:
Saypol, J.M., Roth, B.J., Cohen, L.G. et al. Ann Biomed Eng (1991) 19: 317. doi:10.1007/BF02584306

Abstract

We present a theoretical comparison of the electric field produced in the brain by three modalities of transcranial stimulation of the cortex: magnetic stimulation, bifocal electric stimulation, and unifocal electric stimulation. The primary focus of this comparison is the focality and direction of the electric fields produced. A three-sphere model is used to represent the scalp, skull, and brain. All electric fields are calculated numerically. For magnetic stimulation we consider only a figure-of-eight coil. We find that magnetic stimulation produces the most focal field, while unifocal electric produces the least. Fields produced during magnetic stimulation are parallel to the head surface, while fields produced during electric stimulation have components both parallel and perpendicular to the head surface. The electric field produced by magnetic stimulation is shown to be insensitive to the skull conductivity, while that produced by electric stimulation is very sensitive to it.

Keywords

Magnetic stimulationElectric stimulationElectric fieldCortex

Copyright information

© Pergamon Press plc 1991