Sampling pad-electrode configurations with a high density electrode array for transcranial direct current stimulation

Abstract

Transcranial Direct Current Stimulation (tDCS) is a non-invasive neuromodulation technology that is under investigation as a treatment for a variety of neurological conditions such as epilepsy, Fibromyalgia, depression, Alzheimer’s disease, Parkin-son’s disease and stroke. Today, sponge-electrode pads are commonly used for current injection in tDCS. Research studies on tDCS often use computational model to provide guidance on the placing of sponge-electrode pads. However, the expertise and computational resources needed for Finite Element Modeling (FEM) makes modeling impractical in a clinical setting. The objective is to make the exploration of diUerent electrode conVgurations accessible to practitioners by separating it from the computationally demanding process of current Wow modeling. To efficiently estimate current distributions for arbitrary pad configurations pad electrodes are simulated with an array of high-definition (HD) electrodes and an efficient linear superposition is used to then quickly evaluate different electrode configurations. Numerical results on 10 different pad configurations on a normal individual show that electric field intensity simulated with the sampled array deviates from the solutions with pads by only 5% and the locations of peak magnitude Velds have a 94% overlap when using a dense array of 336 electrodes. Best results are obtained when assuring complete coverage of the electrode pad with sampled electrodes. The precise distribution of currents among the HD electrodes is of minor importance, making the uniform distribution an obvious choice. Computationally intensive FEM modeling of the HD array needs to be performed only once. The present results confirm that using these models one can now quickly and accurately explore and select pad-electrode montages to match a particular clinical need.