Hopkins study proves cochlear implants prevent or reverse damage to brain's auditory ne...( brain where the signals are translate...),Health

Unlike hearing aids, which simply amplify sound through an intact auditory nerve-to-brain system, cochlear implants are much more complicated. Composed of two parts, the devices simulate hearing by picking up sound through an external microphone located behind the ear and outside the scalp and then transmitting sound as electrical signals across the skin to an implanted receiver that is directly attached to the brain.

In the Science report, Ryugo, with graduate student Erika Kretzmer, B.S., and Hopkins professor of otolaryngology John Niparko, M.D., report comparisons of brain tissue containing auditory nerve fibers taken from cats that were born deaf. Three of the cats underwent implants within months of birth, and four did not get implants at all.

Both groups of cats were then exposed to three months of sound stimulation, in which the researchers played music and let the animals run around the lab, with its various and everyday background noises. Included with the deaf cats was a group of three similar cats with normal hearing for further comparison.

The miniaturized cochlear implants were very similar to those currently in use in children.

To gauge the animals' hearing development, the deaf cats - both with and without implants - were subjected to a unique sound, one for each cat, that measured the cat's response to cues, such as the sharp clapping of hands or ringing of a bell, to signify a food reward nearby. Within in a week, implanted kittens responded to their individual sound cues, rushing to collect their food reward, while those without implants did not.

Brain tissue analysis later showed that cats with implants developed regions, called synaptic connections, between connecting auditory nerve cells that closely resembled those of normal cats. The auditory nerve fibers contained plentiful supplies of synaptic vesicles, which store the tr
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Contact: David March
dmarch1@jhmi.edu
410-955-1534
Johns Hopkins Medical Institutions
1-Dec-2005