Characterization of the auditory system responses to infrared neural stimulation of the cochlear nucleus
The aim of this project is to study the use of pulsed infrared laser light to stimulate the central auditory system. This novel approach may be a means to improve the efficacy of the current generation of electrically based Auditory Brainstem Implants (ABI). Infrared neural stimulation (INS) has been shown to activate peripheral nerves and other excitable cells. This method appears to achieve a stimulation that is more spatially selective than traditional electrical methods. In this project, the use of INS as a means of activating the cochlear nucleus (CN) of a rodent model is investigated. To characterize the response of the auditory system to INS of the CN, optically evoked auditory brainstem responses (ABR) as well as neurophysiologic multiunit recordings from the central nucleus of the inferior colliculus (IC) are obtained and analyzed. One aim of this project is studying the effects on the responses of different laser parameters, such as the pulse duration, the peak power, the laser wavelength and the stimulation pulse rate. A second aim is identifying the importance of the stimulation location on the surface of the CN in comparison with electrical stimulation. Finally, due to the known optophonic artifact generated by the infrared laser, the effect of deafening of the animals on the responses is studied. The results show a successful activation of the auditory system of normal hearing animals, recorded both with ABR and IC recording techniques. The laser peak is the only parameters having a significant effect on the response. In deafened subjects, no significant responses can be recorded. The conclusions of this study are that the optophonic effect predominates on the responses in hearing animals, and that INS alone is not a suitable technique for an ABI. Further work involves CN local responses measurements, as well as characterization of the cell types targeted by INS. Bimodal stimulation with combined INS and electrical stimulation is also a promising technique for the improvement of the ABI.
Record created on 2014-03-06, modified on 2016-08-09