Modeling the impact of local and distant electrode configuration on the stimulation pattern in micrometer-size neural probes

Electrical deep brain stimulation is a valuable last resort for the treatment of severe brain disorders when pharmaceutical drugs have proven to be ineffective for a particular patient. A major challenge of DBS is to achieve a high selectivity to allow efficient local stimulation of desired brain regions while minimizing side effects in neighboring regions., For discrimination at a single neuron level, we need electrodes of the same size of magnitude as that of the neurons which are in the 5 to 10 mum range. Exploration of the optimum configuration of a multitude of these microelectrodes requires finite element modeling (FEM) as an important tool for understanding the field distribution from these microelectrodes. Based on simulations in a 3D-FEM of a 10-contact 50-mum contact-size neural probe, we can show that configuring the neighboring electrodes around a stimulation electrode can be used for increasing field penetration depth into tissue. In addition, we investigate field asymmetry effects based on surrounding electrodes and the probe edge.