Bridging macroscopic and microscopic modeling of electric field by brain stimulation

BackgroundModeling the electric field (E-field) on the microscopic scale improves our understanding of brain stimulation modalities and modeling methods but requires careful consideration of the conductivity values and correction of the field amplitudes to match conventional models on the macroscopic scale. ObjectiveWe analyze the correction step and discuss its relevance and implications for E-field modeling efforts bridging the macroscopic and microscopic scales. MethodsWe provide the theoretical framework for comparing microscopic and macroscopic models and describe approaches for effectively and efficiently matching the E-field amplitude and tissue conductivity. ResultsConsistent results can be obtained for brain stimulation models on different scales with appropriately selected conductivity and E-field amplitudes. ConclusionMicroscopic E-field models enable numerical estimation of conductivity of macroscopic homogenous neural tissue from microscopically realistic brain samples and exploration of the effect of microscopic E-field perturbations on neural activation threshold by brain stimulation, therefore improving modeling accuracy.