Conductivity Based Current Focalization in Transcranial Direct Current Stimulation: A Simulation Study

摘要

Transcranial direct current stimulation (tDCS) is a method for stimulation of the brain noninvasively by applying direct current through surface electrodes. Conventional tDCS uses two large pad electrodes on the scalp for current injection. Different studies in this field have shown the importance of electrode positions on the amount of current intensity delivered to different parts of the brain. In recent investigations an array of small electrodes has replaced two large pad electrodes in order to increase the amount of delivered current. Finding an optimal stimulus pattern has been of great interest in such arrays. In this article we use a constrained weighted least squares beamforming approach to find a unique stimulus pattern which delivers maximum current to the target site. By using a spherical head model and considering resistivities of the brain layers for choosing the weights of the beamformer and solving a convex optimization problem, we propose a method to improve the maximum induced electrical field up to 20% in the region of interest in comparison by the existing methods.