Frequency Dependent Electromagnetic Fields: Models Appropriate for the Brain

Citation

Leong, Harrison Mon Fook (1986) Frequency Dependent Electromagnetic Fields: Models Appropriate for the Brain. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/TNQ6-P071. https://resolver.caltech.edu/CaltechETD:etd-03192008-111015

Abstract

This dissertation addresses the problem of modeling electromagnetic fields in and about the brain-skull-scalp system that are generated by active neural populations. Specifically, frequency dependence of Maxwell's fields is explored for the case of a dipole-like current source embedded in a spherical conductor surrounded by a vacuum. Frequency dependence was found to be small. Loosely, the difference between frequency dependent and frequency independent fields reached approximately 1% at 10³ Hz and reached up to 16% at 10⁴ Hz. Frequency dependence was found to be highly dependent on conductivity, the size of the conductor, and on the phase of generated fields. These findings indicate that the degree to which the magnetic field is coupled to the electric field depends on interference patterns occurring within the conductor. Several highly distinguishable exceptions to general trends in the data were found to be consistent with this view.

Thesis Files