Researchers Discover How Brain Region Helps Us Switch From Passive to Active Listening
Study of Hearing in Different Contexts Could Offer Insights Into Sensory Impairment Disorders
University of Maryland biologists have found that an unexpected area of the brain, the orbitofrontal cortex, plays a central role in helping people pay closer attention to sounds in specific contexts.
Photo illustration by Adobe Stock
Ever notice how you can suddenly hear your refrigerator humming in the background when you focus on it? Or how your name being spoken catches your attention even in a noisy crowd?
The human brain is remarkably adept at detecting, filtering and reacting to sounds, but how it does all that remains a mystery. Now, biologists at the University of Maryland are a step closer to solving that mystery.
In a discovery published Thursday in the journal Current Biology, the team found that the orbitofrontal cortex (OFC), a brain region associated with decision-making but not typically linked to hearing, plays a central role in helping a primary hearing center of the brain known as the auditory cortex adapt to changing contexts or situations.
“Our hearing doesn’t just depend on the sounds around us. It also relies heavily on what we’re doing and what’s important to us at that moment,” explained UMD biology Assistant Professor Melissa Caras, the paper’s senior author. “Understanding the neural mechanisms responsible for these adjustments can also lead to a better understanding of and potential treatments for neurodevelopmental disorders like autism, dyslexia or schizophrenia—conditions where sensory regulation goes awry.”
A diagram of the connection between the orbitofrontal cortex and the auditory cortex in the brain. (Image courtesy of Melissa Caras)
To closely examine the brain circuitry involved in the hearing process, the researchers turned to gerbils, small mammals with a hearing system similar to that of humans. The animals were exposed to sound patterns in two different contexts: In one, the animals listened to sounds passively without needing to do anything. In the other, the animals had to perform a specific action in response to the sounds they heard. By recording and manipulating the brain activity of the animals, the team discovered that the OFC helped the animals switch between passive and active listening.
“In short, the OFC sends signals to the auditory cortex when it’s time to pay closer attention to sounds,” Caras said. “It’s not certain whether the signals are sent directly or indirectly via an intermediary brain region, but we do know that activity in the OFC is essential to how the gerbils behaved in our experiments.”
When the OFC was silenced, the animals’ auditory cortex did not switch between passive and active listening, impairing their ability to pay attention to and react to a behaviorally relevant sound.
“It would be as if I told you to suddenly pay attention to your refrigerator humming in the background,” Caras said. “If your OFC was silenced and unable to send a signal to your auditory cortex, you might have difficulty doing so because the ability to rapidly alter your sound perception would be impaired.”
While this study was conducted in animals, Caras said the findings may have notable implications for human health and well-being. The ability to quickly shift attention to important sounds is essential for day-to-day activities including communicating with others and navigating busy or dangerous environments. The team’s work could pave the way for researchers and health care professionals to develop better strategies for improving hearing in both healthy individuals and those with sensory impairments, she said.
“We’re just beginning to understand how the brain fine-tunes hearing sensitivity in response to sudden shifts in behavioral contexts,” Caras said. “We plan to explore exactly how the OFC communicates with the auditory cortex and see whether it’s possible to strengthen the connection and improve hearing ability.”
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