Study Maps Brain’s Ability to Comprehend Sound
Research identifies genes responsible for how the brain processes and perceives sound
By Erik Robinson, Oregon Health & Science University
New research from Oregon Health & Science University (OHSU) and collaborating institutions reveals the complex orchestration of neurons in the brain that turns raw noise—the compression of airwaves and pressure on the inner ear—into the ability to, for instance, understand speech, enjoy music, and discern train whistles from car horns.
The study was published in the journal Nature Communications in January 2025.
“Our ability to understand the meaning of sounds depends on the ability of the brain to represent whether the sound is high- or low-pitched, loud or soft, near or far,” says Laurence Trussell, Ph.D., a professor of otolaryngology–head and neck surgery in the OHSU School of Medicine and scientist in OHSU’s Vollum Institute. “All of that requires very specialized neurocircuitry and highly specialized types of neurons in the brain.”
(a) Diagram of the mouse cochlear nucleus (CN) showing different cell types and their locations. (b) Visualization of 31,639 CN neurons grouped by gene activity, with clusters labeled by key genes. (c) A tree diagram shows how the clusters are related, and a chart highlights key gene activity in each group. More details and credit: Jing et al./Nature Communications
Researchers at OHSU, Baylor College of Medicine, and Texas Children’s Hospital collaborated on the study. Using a technique developed by lead author Xiaolong Jiang, Ph.D., an associate professor of neuroscience at Baylor, the study, which uses a mouse model, reveals the unique patterns of gene expression in specific neurons in the brain that process the signals of sound and enable communication.
This research builds on a previous discovery by Vollum Institute researchers, who in 2022 revealed the architecture of the inner ear in near-atomic detail. That study showed the physiology of the inner ear, which converts vibrations into electrical signals the brain translates as sound.
Trussell and Ngodup in front of their related poster at the 2023 ARO (Association for Research in Otolaryngology) MidWinter Meeting in Orlando.
The new study reveals how the brain’s cochlear nuclear complex processes those electrical signals from the ear, leading to the perception of sound.
“Those electrical signals don’t have much meaning unless they’re integrated over time and across the two ears,” Trussell says. “The brain has to pull in all of this information and make sense of it. That requires a rich neural circuitry in the brain, with neurons that have very specific properties and jobs to fulfill.
“It’s an amazing process, and now we know the genes that make that happen.”
According to the Baylor researchers, some cells respond to sudden, sharp noises while others detect changes in pitch or fluctuating sounds, such as those found in speech or music. Knowing which cell types govern these different functions allows scientists to develop more targeted and effective treatments for hearing impairment.
“For some of these genetic forms of deafness, gene therapies that only treat the inner ear may not be sufficient,” Trussell says. “Going forward, we’re going to be able to take advantage of this information by looking at how these properties are altered during hearing loss.”
This originally appeared on the OHSU website. Laurence Trussell, Ph.D., is a 1991 Emerging Research Grants scientist, and study coauthor Tenzin Ngodup, Ph.D., an assistant professor at the University of Washington, is also a past ERG scientist, whose 2018 grant was generously funded by the Les Paul Foundation.
Baylor College of Medicine also prepared a story on the paper with additional details here.