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'Laser tweezers' may help the hard of hearing

February 05, 2003

A University of Sussex neuroscientist has been awarded £775,000 by the Medical Research Council to continue his research into the causes of deafness, by looking at hair cells in the ear.

"Hair cells are the sensory receptors in the ear. Sound vibrates the hairs, which produces an electrical current, and this current starts a chain of events that the brain then interprets as sound," explains Dr Corné Kros.

A new £120,000 microscope will be used to manipulate the hair bundles on the hair cells using 'laser tweezers'. At the moment this is done using a jet of fluid instead of a laser, but this works only up to a frequency of 1 kHz, whereas the human ear can hear up to a frequency of 20 kHz.

"The ear is a bit like a rolled-up piano with one end sensitive to low frequencies and the other to high frequencies," Dr Kros explains. "What I'm interested in is to find out what the essential differences are between high- and low-frequency hair cells."

In future, his work may make possible treatments for deafness in humans that is due to a loss of function in these hair cells.

"Deafness has two main categories," says Dr Kros. "One is early onset deafness, which happens in about one in 800 children, usually due to a specific genetic defect. Much more common is old-age deafness, which is due to a loss of function in these hair cells, particularly the high-frequency ones.

"We know a lot about what makes the heart tick, but we don't know a lot about what makes the ear work. If you know what sort of molecules make these hair cells work, drugs could be developed to affect them and improve hearing."

Dr Kros hopes it may at some point become possible to regenerate these hair cells: "Birds can do this, but for some reason mammals cannot."

Sussex, University of