Hearing can be Restored

Adults who have lost their sense of hearing have reason to hope as scientists work on new ways to restore this ability.

Researchers have tracked a cell-to-cell signalling pathway that designates the future location of the ear's sensory organs in embryonic mice. The scientists succeeded in activating this signal more widely across the embryonic tissue that becomes the inner ear.

Presbycusis (Age-related Hearing Loss)-Causes-Symptoms-Diagnosis-Treatment-FAQs
Presbycusis (age related hearing loss) is the gradual loss of hearing that occurs as people get older. Presbycusis involves progressive sensorineural hearing loss.

"As the population ages, there's a great interest in discovering how to regenerate the inner ear sensory cells that we need for our hearing and balance," said Olivia Bermingham- McDonogh of the University of Washington.

"Both of these falter as we get older-we get hard of hearing and unsteady on our feet-due to accumulated destruction of the sensory cells in the inner ear," she added.

The goal of their research is to develop ways to restore inner ear sensory hair cells in people who have lost them due to age, excessive noise or other toxic damage.

Anatomy of Ear and Hearing
Ear converts sound waves into electrical impulses that are transmitted to the temporal lobe of the brain through the auditory nerve. It consists of outer, inner and middle sections.

In order to devise a way to restart hair cell formation in the adult ear, Bermingham-McDonogh's group studied how hair cells are made in the first place during ear development.

They could encourage the formation of new building foundations throughout the inner ear. Once these new sensory patches were made, new hair cells and support cells were properly produced within them.

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So by starting the ball rolling with the Notch signal, the researchers observed that the rest of the developmental processes followed along correctly.

The team is now studying ways of manipulating the Notch pathway in the adult inner ear to see if this will stimulate hair cell regeneration in the hearing and balance organs.

How Hearing Works
95 percent of the cells that shuttle sound deep from inside the ear to the brain are big neurons that have explained most of what scientists know about how hearing works.

If ways could be found to safely re-start particular Notch signals in adults, therapies might be designed to regenerate specific tissues, like nerves, and thereby repair damage and restore lost function, like hearing.

The findings are reported this week in the early online edition of Proceedings of the National Academy of Sciences.

Source-ANI