This document discloses, among other things, systems and methods for determining volume of activation for spinal cord stimulation (“SCS”) using a finite element model (FEM) circuit to determine a FEM of an implanted electrode and a spinal cord in which the electrode is implanted, a Fourier FEM solver circuit to calculate a potential distribution in the spinal cord using information from the FEM circuit and a capacitive component of at least one of the implanted electrode and the spinal cord, and a volume of activation (VOA) circuit to predict a VOA using the potential distribution and a neuron model.