Jay Rubinstein - US grants

computational neuroscience; ganglion cell; model design /development; cochlear implants; neural conduction;

nervous system disorder therapy; human therapy evaluation; cochlear implants; sensorineural hearing loss; tinnitus; acoustic nerve; auditory stimulus; patient oriented research; electrodes; human subject; medical implant science; clinical research;

[unreadable] DESCRIPTION (provided by applicant): High levels of speech perception in quiet are currently available to a significant percentage of modern cochlear implant recipients. In a noisy background, however, particularly if that noise is competing speech, speech perception is dramatically impaired. One possible method for improving speech perception in noise is to improve the temporal representation of speech in discharge patterns of electrically stimulated auditory nerve fibers. This method would also be expected to improve the performance of bilateral implant recipients on tasks requiring brainstem analysis of interaural timing. Detailed biophysical models and animal studies have demonstrated that improved temporal representation can be accomplished through the use of "conditioning stimuli" - trains of unmodulated high-rate pulses that desynchronize activity of auditory neurons to competing signals. Use of this procedure has led to dramatically increased speech perception in quiet and/or noise in some subjects, but not in others. The goal of the proposed work is to optimize the presentation of both the speech signal and the conditioner so as to maximize speech perception in quiet and noise for unilateral implant recipients, as well as improve perception of temporally-based lateralization and binaural unmasking in bilateral implantees. Because temporal pitch mechanisms demand accurate place information if they are to be useful, and pitch is thought critical for speech discrimination in competing speech, filter-to-electrode mappings will be manipulated in conditioned speech processors to maximize performance on a test of spondees in steady-state noise, "babble noise", temporally modulated noise, as well as on HINT sentences in speech-shaped noise. The results will allow optimization of conditioned processors for unilateral and bilateral cochlear implant recipients. In those bilateral implant recipients who have interaural timing perception for electrical stimuli in the physiologic range, this work has the potential to provide significant additional binaural benefits from a clinical speech processor beyond those currently available via interaural amplitude differences. In unilateral implantees, this work has already demonstrated substantial benefit in a limited number of subjects; it is our goal to deliver these benefits to the broader population of implant recipients. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Vestibular disorders exact a huge toll in lost productivity and quality of life. The bilateral loss of vestibular function is currently a disorder without effective treatment other than rehabilitative strategies which cannot restore normal vestibulo-ocular or vestibulo-spinal reflexes. Due to the extraordinary success of cochlear implants, there has been a major effort to develop a similar neural prosthesis for the diseased vestibular system. We have developed a vestibular neurostimulator, studied it in rhesus monkeys, and performed four human implants under an FDA investigational device exemption for the treatment of uncontrolled Meniere's disease. Our four human subjects have had profound hearing loss postoperatively and significant loss of electrically-evoked responses has been observed in all of our human subjects and some of our monkeys over months postoperatively. We propose a modification to our existing devices to provide greater stability within the labyrinth and to partly restore hearing in the implanted ear. We also propose a detailed series of longitudinal human studies with the new design to characterize the function of a gyroscopic sensor that we have developed for the treatment of vestibular loss as well as safety studies of the new design in non-human primates. These studies will greatly enhance our understanding of the effects of a vestibular implant in humans and allow us to develop an investigational device exemption for the treatment of uncompensated unilateral and bilateral vestibular loss.