The human nervous system is among the most complex biological structures on this planet. The brain alone is composed of tens of billions of cells \cite{Pakkenberg_1988} and is responsible for coordinating the behavioral responses to the sensory inputs of the body. The nervous system can be interacted with through electrical, optical mechanical and chemical means. Each of these methods has its limitation, particularly when it comes to selectivity. Achieving high selectivity is critical to understanding and controlling the nervous system.