To explore the improvement probability of cochlear implants' performance, researchers began trying to use laser pulse as s stimulus to evoke neural activity. Professor Tian Lan's research team makes intensive studies on the characteristics of light signal stimulation of auditory nerve cells and establishes optical bionic ears research platform based on signal processing theory and photo-electric conversion technology. And the experiments of the real-time detection of intracellular calcium concentration under the laser radiation was carried out by specific fluorescent indicator staining based on calcium imaging. The spiral ganglion cells of mice were cultured in vitro. After fluorescent indicating, morphologic observation under optical microscope, Fura⁃2 calcium ion fluorescence excitation, intact morphology cells selection, fixing the optical fiber, the spiral ganglion cells were irradiated by different wavelength laser, including visible light (450nm) and near infrared light (808nm,1065nm). The intracellular calcium concentration was monitored by calcium ion imaging. It was found when 450 nm laser stimulates spiral ganglion cells, the intracellular calcium concentration was strongly increased, however, for other wavelength laser stimulation, there was no obvious relative response. And the sensitivity expression of the cells under laser was related with the wavelength and the optical fiber location of the laser. This found is of great theoretical value to further study the characteristics of auditory loop stimulated by optical signals and the integrated manufacturing of optical cochlear implant system.

This research was published in the journal "Chinese Journal of Otorhinolaryngology Head and Neck Surgery"(2020) with title "In vitro study on signal transduction in mice spiral ganglion cell stimulated by multi‑wavelength laser based on calcium imaging".