Cell membrane tethers offer clues to hearing loss
By Graciela Gutierrez
When William Brownell, Ph.D., considered how he was going to study mechanical functions in the ear that affect hearing, he knew he was going to have to figure out how to make a tether – not just an ordinary one. He had to make it out of an ear structure itself.
In collaboration with Bahman Anvari, Ph.D., professor of bioengineering at the University of California, Riverside, he has developed a way to pull a portion of the membrane of an inner ear hair cell away from the cell itself, forming a tether-like structure.
Pulling tethers lets researchers see membrane response
"Think of a balloon, the air is the cell, and the rubber is the membrane," Brownell said. "Pulling on the rubber, or membrane, allows us to clearly see what it is made of."
Using different levels of force, he and his colleagues pulled these "tethers." This enabled them to see how the membrane responds mechanically. His team has developed computational models that allow them to analyze the force measurements in order to understand how the membrane reacts to different levels of force.
"Sound waves move through the ear at different forces depending on the pitch," Brownell said. "The cell membranes act as motors that modulate the electrical information the ear sends to the brain, which allows us to understand what we hear."
Studying membranes offers clues to why hearing loss occurs
When hearing loss occurs, a part of the mechanical function of the inner ear hair cell membrane isn't working correctly. Brownell said these computational models will help doctors and researchers understand exactly when that happens.
"This could one day help us to understand what causes different forms of hearing loss and how to fix it," Brownell said. "In order to understand why you hear, you have to understand the underlying mechanism of the cells."
Others who contributed to this study include Drs. Alexander Spector, Kristopher R. Schumacher and Aleksander Popel of Johns Hopkins University.
