Inner Ear Nerve Cells Warn Brain of Damage
Baltimore, MD -- Some nerve cells in the inner ear can signal tissue damage in a way similar to pain-sensing nerve cells in the body, according to new research from Johns Hopkins. If the finding, discovered in rats, is confirmed in humans, it may lead to new insights into hyperacusis, an increased sensitivity to loud noises that can lead to severe and long-lasting ear pain.
“We are still a long way from being able to treat hyperacusis,” says Paul Fuchs, Ph.D., professor of otolaryngology-head and neck surgery, neuroscience and biomedical engineering at the Johns Hopkins University School of Medicine, “but our results suggest that cells called type II afferent neurons are similar to pain-sensing neurons in the rest of the body, so lessons about interventions elsewhere could apply to the ear, too.”
A summary of the research were published online in the journal Proceedings of the National Academy of Sciences during the week of Nov. 9.
The new discovery came as a result of interest in why this small subset of afferent nerve cells — nerves that take information from the inner ear to the brain — are quite insensitive to sound. “If they aren’t very good at relaying sounds, what are they doing?” says Fuchs.
Fuchs and his team knew that these type II afferents connect to specialized sensory cells in the ear of mammals. These so-called outer hair cells amplify the sound waves that enter the inner ear, giving mammals very sensitive hearing over a wide range of frequencies. But, according to Fuchs, this specialization comes at a cost. Continue>
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