Frequency domain modeling of volume conduction of single muscle fiber action potentials

An inhomogeneous frequency-dependent model of volume conduction in skeletal tissue is used to calculate a transfer function between injected membrane current and extracellular action potential in the frequency domain. This model accounts for tissue structure and microscopic electrical parameters (intra- and extracellular conductivities and membrane impedance) and represents the volume conductor by an extensive electrical network. Results obtained with the model are compared with those of a conventional homogeneous volume conductor model. The comparison shows a significant influence of tissue structure and microscopic electrical parameters close to the source. As a result, the transfer function close to the source is less sensitive to the frequency content and conduction velocity of the membrane current, compared with results of the homogeneous volume conductor approach.