Functionalized anatomical models for EM-neuron interaction modeling

The understanding of interactions between electromagnetic (EM) fields and nerves is crucial in contexts ranging from therapeutic neurostimulation to low frequency EM exposure safety. To properly consider the impact of induced field inhomogeneity on non-linear neuronal dynamics in vivo, coupled EM-neuronal dynamics modeling is required. For that purpose, novel functionalized computable human phantoms have been developed, of which the implementation and systematic verification of the integrated anisotropic quasi-static EM solver and neuronal dynamics modeling functionality, based on the method of manufactured solutions and numerical reference data, is described. Electric and magnetic stimulation of the ulnar and sciatic nerves were modeled to help understanding a range of controversial issues related to the magnitude and optimal determination of strength-duration (SD) time constants. The results indicate the importance of considering the stimulation-specific inhomogeneous field distributions (especially at tissue interfaces), realistic models of non-linear neuronal dynamics, very short pulses, and suitable SD extrapolation models. These results and the functionalized computable phantom will influence and support the development of safe and effective neuroprosthetic devices and novel electroceuticals, and furthermore assist the evaluation of existing low frequency exposure standards for the entire population under all exposure conditions.