Simulation of action potentials in a one-dimensional bidomain

An approximate method of calculating action potentials in a nerve fiber within a coaxial sheath is presented. The method is of the implicit type, but it avoids any large matrix inversion and is adapted to run conveniently on a small PC/AT. It produces traces of the extracellular voltage V/sub out/, which is not calculated by other methods, as well as the intracellular potentials V/sub in/. For homogeneous fibers with small sheath resistance, V/sub out/ is proportional to d/sup 2/V/sub in//dz/sup 2/, as expected. In more complex cases, V/sub out/ remains small, but its shape is hard to predict. One such example is presented in which an extracellular voltage trace of novel shape is calculated.<
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