NIH grant advances Creighton research into hearing loss
For most people, hearing seems like a one-way process. Sound enters the ear, travels to the brain and is interpreted. But hearing is more complex.
As the brain processes sound, it also sends signals back to the ear through a little-understood network known as the auditory efferent system. This feedback pathway helps regulate hearing sensitivity and protect the auditory system from damage, yet researchers still know relatively little about how it functions, particularly after hearing loss.
With support from a $524,205 R21 grant from the National Institutes of Health’s National Institute on Deafness and Other Communication Disorders (NIDCD), Hui Hong, PhD, assistant professor of biomedical sciences at Creighton University School of Medicine, will investigate how this overlooked communication system changes after noise-induced hearing loss and whether those changes help or hinder recovery.
Her findings could improve scientists’ understanding of hearing disorders and lay the groundwork for future therapies that complement existing treatments such as hearing aids and cochlear implants.
Why the auditory efferent system matters
Noise-induced hearing loss affects hundreds of millions of people worldwide and is often accompanied by tinnitus, commonly described as ringing in the ears, and hyperacusis, an increased sensitivity to everyday sounds. Although researchers have long known about the auditory efferent system, little is understood about how it responds after hearing loss.
“I’m interested in this auditory efferent system and how it plays a role in noise-induced hearing loss,” Hong said. “Not many people are aware of this auditory efferent system, even in healthy conditions.”
Hong’s project will investigate whether the brain’s feedback system helps repair hearing after acoustic injury or instead contributes to additional hearing disorders such as tinnitus and hyperacusis. Understanding that distinction could help researchers determine whether future therapies should increase or decrease activity within the auditory efferent system.
If the auditory efferent system helps protect or restore hearing, scientists may one day look for ways to strengthen it. If it contributes to further dysfunction, they may instead look for ways to reduce its activity.
Looking deeper with Patch-seq
To answer those questions, Hong will use Patch-seq, a cutting-edge technology that combines whole-cell electrophysiological recordings with single-cell gene expression analysis.
The approach allows researchers to record how an individual neuron functions while it is alive and then analyze the genes expressed within that same cell. By combining functional and genetic information, Patch-seq provides a detailed picture of how hearing loss reshapes neural circuits in ways that traditional methods cannot reveal.
“The technique we use is called patch clamp technology, which allows you to use a very sharp electrode to record from a single cell when it’s alive,” Hong said. “You can record their activity alive.”
Patch-seq builds on that approach by pairing live cellular recordings with genetic analysis. The technology is beginning to emerge in auditory neuroscience, but Hong’s work places Creighton among the first to use it to study the auditory efferent system.
“It’s a very cutting-edge tool,” Hong said. “It allows you to not only record live activity from the cell but also analyze its genes.”
Hong’s project will integrate physiological, transcriptomic and computational approaches to identify the genes, proteins and neural activity altered after noise-induced hearing loss. Understanding these changes could reveal new molecular targets that may someday be used to restore auditory function.
Opening new possibilities for treatment
Although the project is rooted in basic science, its long-term goal is practical: to better understand how the brain responds to hearing loss and how that knowledge could inform future treatments.
For decades, the auditory efferent system has remained one of the least understood parts of the hearing pathway. Despite major advances in cochlear implants and hearing aids, current hearing therapies largely ignore the auditory efferent system. By studying how it changes after noise-induced hearing loss, Hong hopes to fill an important gap in scientists’ understanding of how the brain and ear work together.
That knowledge could shape future hearing research and help identify new approaches to treating hearing disorders, ultimately improving the lives of people living with hearing loss, tinnitus and hyperacusis.
