Increasing the Expression Level of ChR2 Enhances the Optogenetic Excitability of Cochlear Neurons

This study reveals a dose-response relationship between channelrhodopsin expression and optogenetic excitation. Both single cell and organismal responses depend on the expression level of the heterologous protein. Expression level of the opsin is thus an important variable in determining the outcome of an optogenetic experiment. These results are key to the implementation of neural prostheses based on optogenetics, such as next generation cochlear implants, which would use light to elicit a neural response to sound.