Novel VIII Nerve Auditory Prostheses

Direct electrical stimulation of the modiolar portion of the cochlear nerve of subjects with profound hair-cell deafness could restore a useful auditory sense in these individuals. Such stimulation is expected to provide a significant improvement over cochlear electrical stimulation by mitigating the problems associated with cochlear scalar electrical stimulation.

We are conducting the following three phased sets of experiments to validate the use of the Utah Electrode Array (UEA) as a new auditory prostheses.

Anatomical Studies to develop surgical access in animal model and humans.

· Develop surgical access to the modiolar nerve in human.

· Develop the animal model and the surgical access.

· Modify pneumatic insertion technique for implantation in the modiolar nerve.

· Develop and customize recording and stimulation techniques.

Acute feline electrophysiological studies.

· Demonstrate nerve survival during and after surgery.

· Demonstrate that electrical stimulation of the cochlear nerve through a UEA evokes both EABRs (Electrical Auditory Evoked Brainstem Response) and correlated activity in primary auditory cortex (A1) of cats.

· Determine the number of available independent stimulating channels the UEA provides from recordings of evoked A1 activity during varying stimulation protocols.

Chronic biocompatibility studies.

· Evaluate histopathological effects of chronic active and passive UEA implants in cat cochlear nerve.

· Develop chronic UEA implant system with portable programmable multichannel microstimulators.

These physiological, anatomical and histological experiments will provide proof-of-concept of the advantages of direct implantation into and stimulation of cochlear nerve as an approach to an auditory neuroprosthesis. At the successful conclusion of these experiments, we propose to conduct in human experiments directed at exploring the nature of the restored auditory sense.