Abstract
The electro-encephalogram (EEG) and magneto-encephalogram (MEG) are often measured simultaneously. By Faraday's law of induction, the changing magnetic field of the MEG can induce eddy currents in the EEG electrodes. These eddy currents produce their own magnetic field that adds to that produced by current sources in the brain, resulting in an artifact in the MEG recording. It is shown that, under typical conditions, this artifact is less than 1%, but, during measurements of high temporal frequency and high spatial resolution, the artifact can be as large as 3%.
Similar content being viewed by others
References
Gobbele, R., Buchner, H., andCurio, G. (1998): ‘High-frequency (600 Hz) SEP activities originating in the subcortical and cortical human somatosensory system’,Electroencephalogr. Clin Neurophysiol.,108, pp. 182–189
Hamalainen, M. S., Hari, R., Risto, J., Knuutila, J., andLounasmaa, O. V. (1993): ‘Magnetoencephalography-theory, instrumentation, and applications to noninvasive studies of the working human brain’,Rev. Mod. Phys.,65, pp. 413–497
Hari, R., andRisto, J. (1986): ‘Cerebral magnetic fields’,Crit. Rev. Biomed. Eng.,14, pp. 93–125
Roth, B. J., Pascual-Leone, A., Cohen, L. G., andHallett, M. (1992): ‘The heating of metal electrodes during rapid-rate magnetic stimulation: a possible safety hazard’,Electroencephalogr. Clin. Neurophysiol.,85, pp. 116–123
Wikswo, J. P. (1988): ‘High-resolution measurements of biomagnetic fields’,Adv. Cryog. Eng.,33, pp. 107–116
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Murdick, R., Roth, B.J. Magneto-encephalogram artifacts caused by electro-encephalogram electrodes. Med. Biol. Eng. Comput. 41, 203–205 (2003). https://doi.org/10.1007/BF02344889
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02344889