Recently, we published our work on modeling and empirically validating incident TMS coil fields of increasing geometrical complexity:
This method is a unique way to measure the magnetic field induced by a specific TMS coil automatically and in 3D in an MRI scanner, using a phase mapping technique. We also assessed in computer simulations what the influence of TMS coil model complexity means for actually stimulating a human motor cortex.
What we learned was that in-plane detail like spiraling TMS coil wires need to be modeled, and can make a difference when assessing accumulating currents in the motor cortex. Coil winding thickness, on the other hand, does not have much of an influence. These new insights can aid researchers in estimating how much current goes into their stimulated region, and what coil details they should take into account when planning their experiments.