Field modeling for transcranial magnetic stimulation: A useful tool to understand the physiological effects of TMS?

TLDR

Electric field calculations using numerical methods and realistic head models are increasingly employed in TMS research, yet they remain far from being standard tools for practical planning and analysis. The study identifies three key challenges: managing model uncertainties, linking induced fields to physiological stimulation effects, and improving tool usability for non‑experts. A new SimNIBS pipeline is introduced that simplifies the setup and execution of TMS and tDCS simulations via finite‑element methods. The updated SimNIBS version is expected to address these challenges, enhancing field calculation accuracy and user accessibility.

Abstract

Electric field calculations based on numerical methods and increasingly realistic head models are more and more used in research on Transcranial Magnetic Stimulation (TMS). However, they are still far from being established as standard tools for the planning and analysis in practical applications of TMS. Here, we start by delineating three main challenges that need to be addressed to unravel their full potential. This comprises (i) identifying and dealing with the model uncertainties, (ii) establishing a clear link between the induced fields and the physiological stimulation effects, and (iii) improving the usability of the tools for field calculation to the level that they can be easily used by non-experts. We then introduce a new version of our pipeline for field calculations (www.simnibs.org) that substantially simplifies setting up and running TMS and tDCS simulations based on Finite-Element Methods (FEM). We conclude with a brief outlook on how the new version of SimNIBS can help to target the above identified challenges.