Using Lasers To Stimulate The Auditory Nerve

Using Lasers to Stimulate the Auditory Nerve added by Caitlin Padick

On January 4, 2007 the National Institute on Deafness and Other Communication Disorders presented the results of their investigation into the improvement of cochlear implants to decipher sounds when background noise is present. The goal was to find a way to create a more realistic listening experience for those with cochlear implants. Cochlear implants work by allowing sounds to bypass the damaged parts of the inner ear and stimulate the auditory nerve directly. Currently cochlear implants use electrodes to stimulate the auditory nerve, the result is sound that helps the user distinguish a useful amount of sounds from the environment but this in no way approximates natural hearing. Researchers from New Hampshire hope that by using light in the form of lasers to stimulate the auditory nerve directly sound quality will approach that of a hearing person.

Cochlear implants work by replicating the way humans hear using electrodes. The cochlea hears sounds as a range of stimulations. Sound waves that are high pitched hit the part of the cochlea closest to the outside of the ear, correspondingly as the pitch deepens so does the location of the sensory nerve. In a person with a cochlear implant, electrodes located throughout the cochlea react appropriately when a pitch of the correct pitch hits them, the electrodes in turn stimulate the auditory nerve. However the electrodes are not precise and tend to stimulate surrounding parts of the auditory nerve as well producing a muddled sound. Claus Peter Richter M.D, PhD. suggests that using a low level infrared light laser would be more precise in stimulating the correct part of the auditory nerve. In addition to improved sound quality over electrode implants, the laser guided stimulation may also allow the stimulation of smaller nerve endings that are not reached at all by the electrodes. To date the researchers have proven that the use of a laser can stimulate the auditory nerve of laboratory rats with no damage to the nerve endings. They were given a 5 year, 1.68 million dollar grant in September 2006 by the NIDCD to continue their research.

Resource:

National Institute on Deafness and other Communication Disorders. NIDCD-funded Research Explores Use of Laser to Stimulate Auditory Nerve. January 4, 2007. http://www.nidcd.nih.gov/news/releases/07/01_04_06.htm