A generalized theory for current-source density analysis in brain tissue

Abstract

The current-source density (CSD) analysis is a widely used method in brain electrophysiology, but this method rests on a series of assumptions, namely that the surrounding extracellular medium is resistive and uniform, and in some versions of the theory, that the current sources are exclusively made by dipoles. Because of these assumptions, this standard model does not correctly describe 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 the above 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 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 extracellular medium, which provides a direct way to estimate those properties from experimental data, and in particular, estimate the possible contribution of electric monopoles.

Physical Review E, in press, 2011

References in corpus (4)

• Modeling extracellular field potentials and the frequency-filtering properties of extracellular space
• Macroscopic models of local field potentials and the apparent 1/f noise in brain activity
• Model of Low-pass Filtering of Local Field Potentials in Brain Tissue
• A modified cable formalism for modeling neuronal membranes at high frequencies

Cited by in corpus (9)

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• Intracellular impedance measurements reveal non-ohmic properties of the extracellular medium around neurons
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• Generalized cable formalism to calculate the magnetic field of single neurons and neuronal populations
• Kramers-Kronig relations and the properties of conductivity and permittivity in heterogeneous media
• Quasi-Static Approximation Error of Electric Field Analysis for Transcranial Current Stimulation
• Apparent extracellular current density and extracellular space: basis for the current source density analysis in neural tissue