Non-invasive brain stimulation: from field modeling to neuronal activation

Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are the most commonly studied non-invasive brain stimulation treatment options. Over the past years, modeling and simulation of stimulation-induced electric fields have received increased attention. Modeling can take place at three different levels of abstraction. Although some validation of these models has taken place at these levels separately, coupling between the levels through a multi-scale approach and experimental validation of the overall approach has only recently started. This specific coupling might be an important step to unravel the mechanism of action and to ultimately improve the clinical efficacy of non-invasive brain stimulation.