St. Jude finds 'dancing' hair cells are key to humans' acu...( St. Jude Children's Research Hospita...),Health
St. Jude Children's Research Hospital investigators have found that an electrically powered amplification mechanism in the cochlea of the ear is critical to the acute hearing of humans and other mammals. The findings will enable better understanding of how hearing loss can result from malfunction of this amplification machinery due to genetic mutation or overdose of drugs such as aspirin.
Sound entering the cochlea is detected by the vibration of tiny, hair-like cilia that extend from cochlear hair cells. While the cochleas inner hair cells are only passive detectors, the so-called outer hair cells amplify the sound signal as it transforms into an electrical signal that travels to the brains auditory center. Without such amplification, hearing would be far less sensitive, since sound waves entering the cochlea are severely diminished as they pass through the inner ear fluid.
In their studies, Zuo and his colleagues have sought to establish the mechanism by which outer hair cells produce such amplification. Specifically, they wanted to distinguish between two amplification theoriescalled stereociliary motility and somatic motilitythat have resulted from previous studies of the auditory machinery.
The stereociliary theory holds that amplification is produced by intricate vibrations of the bundles of cilia extending from the outer hair cells. The somatic motility theory proposes that the sound signal is amplified by an amplifier protein, called prestin, embedded in the hair cell membrane. Prestin is powered by voltages within the membrane that are produced by mechanical sound vibrations.
This motility is also called dancing because when you electrically stimulate an outer hair cell with a sound, the cell body spontaneously elongates and contracts along with the sound, said Jian Zuo, Ph.D., associate member of the St. Jude Department of Development Neurobiology. It is very dramatic to see these hair cells dance with the sound.
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| Contact: Carrie Strehlau media@stjude.org 901-495-3306 St. Jude Children's Research Hospital Source:Eurekalert |
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