A novel approach to simulate Hodgkin-Huxley-like excitation with COMSOL Multiphysics

A proof of concept for the evaluation of external nerve and muscle fiber excitation with the finite element software COMSOL Multiphysics, formerly known as FEMLAB, is presented. This software allows the simultaneous solution of fiber excitation by 1D models of the Hodgkin-Huxley type which are embedded in a volume conductor where the electric field is mainly dominated by the electrode currents. This way the presented bidomain model includes the interaction between electrode currents and transmembrane currents during the excitation process. Especially for direct muscle fiber stimulation (cardiac muscle, denervated muscle) the effects from secondary currents from large populations of excited fibers seem to be significant. The method has many applications, for example, the relation between stimulus parameters and fiber recruitment can be analyzed.