A generalized theory for current-source density
analysis in brain tissue.
Claude Bedard and Alain Destexhe
Physical Review E 84: 041909, 2011.
Abstract
The current-source density analysis is a widely used method in brain
electrophysiology, but this method rests on a series of assumptions,
namely that current sources are exclusively made by dipoles, and
that the surrounding medium is resistive and uniform. Because of
these assumptions, this standard model cannot be used to estimate
the contributions of monopolar sources or of non-resistive aspects
of the extracellular medium. We propose here a general framework
to model electric fields and potentials resulting from current
source densities, without relying on such assumptions. We develop a
mean-field formalism which is a generalization of the standard
model, and which can directly incorporate non-resistive
(non-ohmic) properties of the extracellular medium, such as ionic
diffusion effects. This formalism recovers the classic results of the
standard model such as the current-source density (CSD) analysis,
but in addition, we provide expressions to generalize the CSD
approach to situations with non-resistive media and arbitrarily
complex multipolar configurations of current sources. We found
that the power spectrum of the signal contains the signature of the
nature of current sources and medium, which provides a direct way
to estimate those properties from experimental data, and in
particular, estimate the possible contribution of electric
monopoles.
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