SimNIBS 4.0: Detailed Head Modeling for Transcranial Brain Stimulation and EEG

Computational modeling of the electric currents in the cortex is an integral part of many brain mapping approaches [1,2]. The currents can be either externally induced by electric (TES) or magnetic (TMS) stimulation, or due to neuronal activity in which case they can be measured using M/EEG. In both cases the current flow is largely shaped by the individual anatomy [3], which implies that reliable stimulation targeting, or source reconstructions, require accurate anatomical models of the head anatomy. In the new version of the open-source toolbox for Simulation of Non-Invasive Brain Stimulation (SimNIBS 4.0), we have improved the accuracy and robustness of the anatomical modeling, and included multiple additional head tissue classes, such as veins and spongy bone. SimNIBS 4.0 also supports lead-field calculations, which allows the improved head modeling to be integrated into EEG source reconstruction algorithms.