The activation function of TMS on a finite element model of a cortical sulcus

TMS is a promising tool for the non-invasive stimulation of the cerebral cortex, with applications in Neurology and the Neurosciences. From cable theory, it is known that the activation function for neuronal stimulation in TMS may contain contributions from the electric field and the component of the electric field gradient along the direction of the nerve. Here we present a calculation of the spatial distribution of the induced electric field by TMS using a finite element model of the cerebral cortex and surrounding tissues. This distribution allows us to calculate the activation function for different experimental conditions, and is expected to provide new insight into the mechanisms of TMS in the cortex.