Cellular Action Currents

Abstract

One of the most conceptually difficult problems in biomagnetism has been to understand the relation between the electric and magnetic fields produced by bioelectric current sources. The ideal method to test our understanding of the relationship between the two fields is to record both fields and to use one to predict the other. This process requires two steps: the solution of the inverse problem for one field to obtain a description of the current sources, and a solution of the forward problem, using these sources, to obtain the other field. Many theoretical and experimental studies have addressed the inverse problem as it relates to the magnetocardiogram. Because of the non-uniqueness of the inverse problem, these studies have generally used equivalent generators based on either multipole expansions or a limited number of discrete current dipoles, rather than physiologically accurate models involving cellular action currents. Similarly, what modeling that has been used to understand the magnetoencephalogram has been limited to one current dipole or a planar distribution of current dipoles.