Electrophysiological mechanisms of single-neuron stimulation using a focused femtosecond laser

Abstract Single-cell stimulation can be effective for investigating neuronal network functions and their relationship with electrophysiological properties of single neurons. Previous studies have reported external stimulation of single neurons with low invasiveness using a focused femtosecond laser. However, laser-induced stimulation mechanisms remain unclear and require further evaluation of their electrophysiological properties. In this study, we evaluated the electrical activity of femtosecond laser-irradiated single neurons using simultaneous fluorescence Ca 2+ imaging and whole-cell patch-clamp recordings. Extracellular Ca 2+ influx and highly frequent action potentials were observed in target neurons after laser irradiation. Upstate membrane potentials are caused by extracellular cation influx through disrupted membranes at the focal spot. These results suggest that single neurons were stimulated by a focused femtosecond laser. The proposed method is effective in clarifying information processing in the brain at the single-cell level.