Ears make their own sound

Nov. 1, 2007 at 2:43 PM
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BALTIMORE, Nov. 1 (UPI) -- U.S. brain scientists discovered cells in the developing ear make their own noise, long before the ear is able to detect sound around them.

The finding, reported in Nature, helps explain how the developing auditory system generates brain activity in the absence of sound and may help people who experience tinnitus -- hearing sounds that seem to come from nowhere.

"It’s long been thought that nerve cells that connect auditory organs to the brain need to experience sound or other nerve activity to find their way to the part of the brain responsible for processing sound," lead study author, Dwight Bergles, of John Hopkins Medical Institutions, said in a statement. "So when we saw that these supporting cells could generate their own electrical activity, we suspected they might somehow be involved in triggering the activity required for proper nerve wiring."

Bergles explained the breakthrough came when it was discovered that adenosine triphosphate, or ATP -- a chemical used in providing cell energy -- was also changing the shape of certain cells.

He said small amounts of free-floating ATP activates only a few nearby hair cells in the ear and he believes these brief bursts of electrical activity may help the hearing system do fine-tuning.

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