A Novel Account for the Large Dielectric Constant of Neural Tissue at Low-Frequency

Abstract

It has been known for sometime that brain tissue show marked low-frequency dielectric dispersion and large permittivity (>10⁶) in a frequency range of 10–100 Hz. We have shown that these properties can be due to electrically long neurites by solving equations that describe a model with a bundle of finite length cylindrical neurites subjected to oscillating extracellular electric fields. We also provide a notion of the apparent extracellular space and a generalized formulation for the EEG inverse problem that takes permittivity into account.