Optical stimulation of excised murine sciatic nerve using 1.8-μm wavelength laser

While recording of compound actions potentials is a mature technique, it becomes problematic to use traditional electrical nerve stimulation on very short nerves due to the large electrical stimulus artifact and short propagation times. Novel methods of stimulation using focused infrared laser radiation may permit stimulation and measurement in closer proximity with much finer spatial resolution than conventional techniques. This project involved the development of a murine sciatic nerve model for action potential stimulus and measurement in vitro, including refinement of a dissection protocol and development of a small-scale stimulation and measurement dish specific to murine sciatic nerve. It demonstrated successful recording of compound nerve action potentials (CNAPs) using traditional current-mode electrical stimulus. Lastly, optical nerve stimulation was attempted on the same nerve prep using an infrared laser source of 1.86um. In this preliminary study, the conventional stimulus was been successfully demonstrated, however the optical stimulus failed to produce measurable CNAPs, We later learned that other investigators have only succeeded with in vivo experiments in the mouse sciatic nerve, and in vitro experiments have not been demonstrated. More work is needed to achieve success in the in vitro model.