Research On The Mechanism Of Laser Stimulation On The Spiral Nerve

In the sixties of the last century, the first cochlear implant with single-electrodehad been produced, after nearly half a century, nowadays, the number of electrodehas reached22. However, between the implanted electrode, their current willinfluence each other. That is why the number of electrode is limited. Only with the22electrodes, people with hearing impairment cannot get a good sound effects.Since the research of stimulating neural using laser emerged, it gives a goodenlightenment to the improvement of stimulus in the cochlear implant. When laserstimulating the auditory nerve, it has a good directivity, the diffusion effect won’tappear, so, if we choose the laser as the stimuli of cochlear implant, in order toachieve the purpose of improving listening quality, we can increase the number ofoptical fiber. At present, in this research field, there are two foreign research groups,so far, there is no research on this field in China. After we have done a lot ofresearch in this field, Harbin institute of technology Shenzhen graduate schoolcollaborates with Shenzhen graduate school of Tsinghua university in the domesticfirst to enter the field of optical cochlear and research on this subject.This paper needs to research the mechanism of laser stimulation on the spiralnerve, it is the preliminary study of the mechanism of laser thermal effect for theoptical cochlear implant project. Through studying the foreign research status, it isclear that what function should be achieved. It needs to collect the data ofsound-induced ABR signal, design a program of animal experiment, build an opticalpath that can get pulse laser light and collect the data of photoinduced CAP signalsynchronizing with the stimulates. Then debug the existing sonoluminescence ABRsignal acquisition platform, build the photoluminescence CAP acquisition platformand use it for the experiment.First is the debugging process of ABR signal acquisition platform when thesound source as a stimulus. This paper illustrates the hardware platform and theperformance of its various parts, which focuses on the software interface of thevarious adjustable parameters. And then through the analysis of the situation thatcollected data is not accurate, we formulate measures for debugging, finally, bycomparing the debug data, we got the optimum parameters of the commissioning.Followed by the determination of animal surgery program. It chooses thespecial instruments for animal experiment and makes a detailed surgery plan forexperiment, through our own practice, the scheme has been improved. The animalcan be used into study after dealing with this surgery. A data acquisition platform of pulse laser induced CAP signal will be set up,analysis the function goals of this platform, choose optical equipments of suitableparameters to construct the light path that can produce pulse laser. By using thesignal from stimulation output port of RM6240multi-channel physiologicalacquisition instrument to as an enable signal of optical shutter, we achieve thesynchronization of laser stimulus and CAP signal acquisition.So far, the necessary conditions of experiments have been fulfilled, we collectthe CAP signal of guinea pig induced by pulsed laser at different wavelengthsthrough this platform. The results illustrate that as the water absorption coefficientof the laser increases, so dose the amplitude of laser-induced CAP signal. Becausethe intensity irradiation we use is too low to induce the photochemical reactionswithin the organization, which indicates that the larger the absorption coefficient,the deeper the penetration depth, the more heat generated through the waterabsorption of the laser beam. At last we get a conclusion that mechanism of laserstimulation on the spiral nerve cells is photo thermal effect. This research directionis proposed in China for the first time, it will be a good guidance to the developmentof cochlear implant of our country.