Single nerve cell’s mechanical response is an important issue for understanding function of nerve system, though, the response has been rarely clear. One of the factors is difficulty to stimulate the single cells by quantitative and controllable mechanical stress with subcellular spatial selectivity. As such mechanical stimulator, our group has focused on shock and stress waves generated by focusing the femtosecond laser under a microscope. When those waves impact on the biological cell, they act as an impulsive force. Although the impulsive force is available as a mechanical manipulator of the single cells, it was not confirmed that it could stimulate the nerve cells. Here we investigated the issue using neuro2a cells extending their neurite as an experimental model of nerve cell. Our results indicated that the impulsive force could be available as the stimulator to cause the mechanical response of the neuro2a cell.
A new methodology to estimate the dynamics of femtosecond laser-induced impulsive force generated into water under microscope was developed. In this method, the position shift of the bead in water before and after the femtosecond laser irradiation was investigated experimentally and compared with motion equation assuming stress wave propagation with expansion and collapse the cavitation bubble. In the process of the comparison, parameters of force and time of the stress wave were determined. From these results, dynamics of propagations of shock and stress waves, cavitation bubble generation, and these actions to micro-objects were speculated.