Hair-Cell Roots Discovered
Hair cells of the inner ear have a previously unknown "root" extension that may regulate sensitivity to sound vibrations and head position, researchers at the University of Illinois at Chicago College of Medicine have discovered. Their findings, reported in the Proceedings of the National Academy of Sciences, indicate the hair-like structures—called stereocilia—are fairly rigid and interlinked at their tops by structures called tip-links.
Using a high-voltage electron microscope at the National Center for Microscopy and Imaging Research at the University of California San Diego, researchers constructed a composite picture of the entire top section of the hair cell. Although current thinking characterizes the roots of the stereocilia as ending in the cuticular plate, the new pictures showed that the roots continue through the plate, make a sharp 110-degree angle, and extend to the membrane at the opposite side of the cell.
Just as the brain adjusts the sensitivity of retinal cells in the eye to light, these results suggest the brain may also modulate the sensitivity of hair cells in the inner ear to sound and head position. When the head moves or a sound vibration enters the ear, motion of fluid in the ear causes the hair cells' tip-links to be displaced and stretched, exciting the cell, which then relays information to the brain.
According to the researchers, the pictures may revolutionize the way scientists think about the hair cells in the inner ear. Search doi: 10.1073/pnas.1101003109.
Brain Makes the Call
Left-brain thinkers are most likely to use their right hand to hold a cell phone to their right ear when talking, according to a recent study from Henry Ford Hospital in Detroit. More than 70% of participants held their cell phone up to the ear on the same side as their dominant hand, despite there being no perceived difference in their hearing in the left or right ear.
To determine possible associations between sidedness of cell phone use and auditory or language hemispheric dominance, the Henry Ford team developed an online survey using modifications of the Edinburgh Handedness protocol, a tool used for more than 40 years to assess handedness and predict cerebral dominance. These findings have implications for mapping the language center of the brain, making less-invasive, lower-cost options possible. The study also offers additional evidence that cell phone use and tumors in the brain, and head and neck may not be linked. Visit Newswise for more details.
The National Institute for Occupational Safety and Health (NIOSH), in partnership with the National Hearing Conservation Association, recently announced recipients of the 2012 Safe-in-Sound Excellence in Hearing Loss Prevention Awards™. The awards honor companies dedicated to preventing noise-induced hearing loss through notable hearing loss prevention practices in the work environment.
"Since noise is everywhere, preventing its negative effects requires the integration of occupational safety and health protection with health promotion," NIOSH director John Howard said. "NIOSH supports this concept, also called Total Worker Health, as the most effective approach to promote health. To effectively maintain healthy hearing, it is important for us to extend preventive initiatives outside the workplace, and this year's recipients offer us compelling examples of this approach."
This year's recipients include Colgate-Palmolive, the first corporation to win the award for its company-wide interventions, including adopting the NIOSH-recommended 85-dBA limit for eight-hour noise exposures, completing multiple noise-control studies in each business location, and documenting cost and noise reduction rates. Other award recipients were the 3M Hutchinson plant in Minnesota—the country's largest 3M manufacturing plant—and the Bechtel National, Inc., BSII, Waste Treatment & Immobilization Plant Project (Richland, Washington), a construction site of 65 acres with four major nuclear facilities. Read more at Safe-in-Sound's website.