Professors research hearing loss, concussions
Kathryn Marshall | Monday, December 5, 2016
Students and faculty members heard more about research at Saint Mary’s during Friday Faculty Colloquium Series presentations by Dr. Jennifer Rowsell, assistant professor of biology, and Dr. Sandra Schneider, associate professor of communicative sciences and disorders.
Rowsell spoke on “Insights into the Restoration of Hearing Loss.” She said there are two types of hearing loss, and she is specifically interested in the sensorineural type, which is when hearing loss results from damage to the cochlea in the inner ear.
This type of hearing loss has multiple causes, including presbycusis, or age. Playing different frequencies of sound demonstrated to attendees how older age decreases the ability to hear high frequency sounds.
“You can speed up this process by exposure to loud noises,” Rowsell said. “In a younger ear, if you are exposed to loud noises it doesn’t necessarily mean that you are going to cause an immediate hearing degeneration or loss, but it may very well cause this to occur a lot earlier in life.”
Mammals naturally lose hair cells as they age, and this results in hearing deficits, Rowsell said. These hearing losses are permanent because the hair cells can’t regenerate, she said.
“These neurons that are connecting to our hair cells are taking information to the brain,” she said. “So what’s happening here is hair cells recognize the vibrations caused by sound waves. Neurons transmit that information to the brain for interpretation … these are the cells that are important for the function of hearing in the cochlea.”
However, fish and birds can regenerate these hair cells. By studying the developmental pathways of hair cells in animals such as birds and mice, researchers like Rowsell can explore different routes of promoting hair cell regeneration in mammals, she said.
One future possibility being explored in research is using stem cells in stem cell therapy to replace lost hair cells.
“First, you have to know the normal developmental pathway, how they make these decisions, if you want to force an undifferentiated [stem] cell down that pathway,” she said.
Schneider’s area of interest is in neurogenic communication disorders, and that interest was explored in her talk “Using Speech Analysis for Concussion Detection and Other Neurological Disorders.”
The lecture began with a video of a hard hit by a football player, who, despite displaying symptoms of having a concussion, played again later in the game.
“It’s an epidemic,” she said. “There are two different types of concussion … after a hard hit, the brain bounces up and back. The cranium is a very hard system. There is nothing it can do, but the brain gets knocked around … the other concussion that they don’t talk about as much is the face mask or any kind of rotational where they grab and twist the brain on top of the brain stem. Both of those are equally damaging.”
Concussions are a significant health problem in the United States, and are the leading cause of death and disability in young people, Schneider said.
These concussions have long-term consequences, including temporary and permanent effects on personality, relationship skills and early onset dementia, Schneider said. She said she often tells her class, “Touch the brain, never the same.”
“Sometimes symptoms don’t manifest themselves immediately to the physician or clinician who is looking that them, and yet [the athlete] will have delayed onset of symptoms where the functional ability it just difficult,” Schneider said. “Unfortunately, 90 percent of concussions go undetected.”
While people are finding ways to cheat current concussion tests, the voice is one thing humans can’t cheat, Schneider said. One example of this is when a student calls home, and their mother knows something is wrong simply by the emotions in the student’s voice.
By collaborating with engineers at Notre Dame, Schneider uses her interest in speech to develop a technology tool to detect concussions, she said. Such collaboration resulted in data collection for over 2,500 subjects, and collecting numerous baseline and after-event recordings.
“We looked at movement,” she said. “Hesitating with movement, pitch level change, also duration rate of what’s going on. Particularly motor speech execution involves about 100 different muscles containing about 100 different motor units. During normal speech 140,000 neuromuscular events are generated every second to produce one monosyllable.”
Using around 40 different motor speech execution biomarkers, Schneider and her collaborators have developed a tool for detecting concussions that has 94 percent accuracy. The idea of using motor speech execution biomarkers has potential future applications in areas such as detecting autism, she said.