On the use of time division multiplexing to improve electrical brain stimulation focality

Abstract Background and objective Selective electrical stimulation of target brain locations (stimulation focality) is a difficult problem because it comprises conflicting goals. The stimulating current density field needs to be strong enough to stimulate targeted locations but weak enough not to stimulate near-by non-targeted locations. The objective of this study is to suggest a methodology for improving electrical stimulation focality based on time-division multiplexing principle. Proposed methodology The complex problem of exciting a group of target locations is decomposed into a series of simpler problems in which a single location is targeted. Time-division multiplexing between the solutions of the simpler problems achieves seemingly parallel excitation of the selected target locations with minimal excitation of non-targeted locations. Results A high fidelity finite element-based simulation of a cortical vision prosthesis is used to demonstrate the proposed idea and highlight important facts about neurons dynamics that must be taken into consideration in order to design a successful time-division multiplexing based stimulation scheme. Conclusion The study offers a clear detailed procedure for designing focal electrical stimulation setups based on time division multiplexing principle. The included results and experiments prove that the proposed strategy is a step forward towards more focal stimulation setups.