Researches On Animal’s Auditory Responses Induced By Fiber-coupled Pulsed Laser

The function of auditory system is auditory perception, in which cochlea acts as a complicated auditory sensor of the auditory system. In the case of cochlea’s disfunction, human and animals would suffer from serious sensorineural deafness. Under this circumstance, we are not able to achieve sound perception and language communication, which directly affect one’s life quality. For sensorineural deafness, electrical cochlea implant(CI) is the most fitted and effective treatment in clinical application. Based on electrical stimulation, cochlea implant bypass damaged portions of the cochlea and directly stimulate the auditory nerves with implanted electrode array.It aids implant user to perform basic speech perception, while it has very poor performance on music perception or under noisy conditions. Electrical stimulation used by CI is constrained by electrode interference and stimulus artifact. The electrode interference has limited the number of electrode channels, while stimulus artifacts plagued simultaneous stimulation and recording. These defects of electrical means directly lead to poor selectivity which even best electrode design cannot overcome. Hence some other stimulation method has been proposed, in which laser stimulation is a very promising one. Laser stimulation has several appealing features: high precision, non-contact with neural tissue, high spatial resolution,In this thesis, we attempt to use pulsed laser coupled with optical fiber to evoke guinea pig’s auditory brainstem response. The appropriate wavelength is chosen by spectral analysis of cochlea tissue and then we designed a pulsed laser system applied on cochlea stimulation. The laser parameter, such as pulse duration, repetition rate, radiant exposure are tunable. Then the optical fiber was carefully placed to let pulsed laser radiate the cochlea modiolus. Optical evoked auditory brainstem responses are recorded for different laser parameters, with electrophysiological measurement devices. In comparison with sound stimuli, we discuss the perception characteristics and physiological mechanism of laser stimuli. The results indicate that laser can fire cochlea neurons and evoke auditory sense, we consider it as a combined result of optoacoustic effect and photothermal effect.