Snapshots of Life: The Biological Basis of Hearing
Posted on by Dr. Francis Collins
Did you know that chickens have ears? Well, here’s the evidence—you’re looking at a micrograph of sensory hair cells that make up the inner ear of Gallus gallus domesticus, otherwise known as the domestic chicken. Protruding from each hair cell is a tall bundle of stiff appendages, called stereocilia, that capture vibrations and enable the chicken to hear everything from grain being poured into a feeder to the footsteps of a wily fox. The flatter area is occupied by supporting cells, which have recently been shown to have the capacity to regenerate damaged or destroyed hair cells.
Peter Barr-Gillespie and Kateri Spinelli of Oregon Health & Science University, Portland used a scanning electron microscope to capture this image—one of the winners of the Federation of American Societies for Experimental Biology’s 2014 BioArt competition—while studying how these cells convert sound waves into brain waves. It is generally known that sound waves cause the stereocilia on each hair cell to oscillate in concert. These vibrating stereocilia trigger electrical changes in the hair cells, which then send signals to the brain. Barr-Gillespie’s group focuses on the actual molecules that build the stereocilia and translate the vibrations into brain signals.
Sensory hair cells are vital for hearing. But when you are crank up the volume on your MP3 player or use loud machinery, the powerful sound waves can break and sometimes snap off the stereocilia, eventually killing the hair cells.
In humans, the destruction of hair cells by noise exposure, injury, or disease can lead to permanent hearing loss, a problem that affects some 26 million Americans. But researchers have discovered that in chickens (as well as in fish, amphibians, and reptiles), supporting cells have the power to regenerate sensory cells within a couple of weeks—restoring the ability to hear. Barr-Gillespie anticipates that a better understanding of these sensory and supporting cells in the chicken may provide clues to treating and possibly reversing hearing loss in humans.
Meanwhile, if you happen to work or live near NIH or have plans to visit our main campus in Bethesda, MD, I encourage you to view this and other winning BioArt 2014 images in person. They are on display in an exhibit at the Nobel Laureate Exhibit Hall inside the NIH Visitor’s Center.
Noise-Induced Hearing Loss (National Institute on Deafness and Other Communication Disorders/NIH)
Barr-Gillespie Lab (Oregon Health & Science University, Portland)
BioArt 2014 (Federation of American Societies for Experimental Biology)
NIH support: National Institute on Deafness and Other Communication Disorders