"The results imply a restoration to some extent of the normal organization through the use of the cochlear implant,” says Manuel Don, PhD, of the House Ear Institute in Los Angeles. “They also claim to find ties between the degree of restored organization and a hearing task. Such ties are of enormous importance in evaluating cochlear implant benefits.” Don was not involved in this study.
Guiraud and her team studied 13 profoundly deaf adults who had received cochlear implants, on average, eight months before the study. Electrical stimulation to the ear allowed the team to locate where in the brain’s auditory cortex various frequencies were processed and come up with a map for these tones. Their results demonstrated that in people who had cochlear implants for at least three months, normal frequency organization was somewhat restored.
"Our results strongly suggest that the recipient’s auditory cortex presents a tonotopic organization that resembles the frequency maps of normal-hearing subjects,” says Guiraud.
In the future, the team hopes to determine in detail the ways in which these maps may change as a result of cochlear implants by studying subjects immediately following implant surgery.
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The work was a supported by a grant from Advanced Bionics Europe.
The Journal of Neuroscience is published by the Society for Neuroscience, an organization of more than 36,500 basic scientists and clinicians who study the brain and nervous system. Guiraud can be reached at jeanne_guiraud@hotmail.com |
