Mechanisms for the light-cell interface in optical cell stimulation

Electric neurostimulation has become an important means of therapy for many different indications such as epilepsy, chronic pain, cardiac arrhythmia or sensory loss. However, an electrode cannot deliver a stimulus with sufficient precision to stimulate single cells in a dense neural network. Concerning sensory devices like a cochlear implant, an imprecise stimulus due to electronic crosstalk results in a blurred sensory impression. Advances in optical neurostimulation have shown great potential to overcome these limitations of electrical approaches by translating precise optical stimuli into electrophysiological signals on a single cell level. We used a neuroblastoma cell line (N2A) to study the effects of different optical stimulation methods, such as glutamate uncaging, gold nanoparticle mediated laser stimulation and optogenetic approaches. The different strategies were evaluated with respect to factors like robustness of the results, cell damage and transferability of the experimental conditions to circumstances in vivo. Thereby, a first attempt was made to assess the feasibility of an optical hearing aid.