New research suggests the orbitofrontal cortex helps switch between passive and active listening and plays a central role in helping the auditory cortex adapt to changing contexts or situations.
American biologists said the orbitofrontal cortex (OFC) was a brain region associated with decision-making but not typically linked to hearing.
However, they found it helped animals switch between passive and active listening.
They are now planning to explore exactly how the OFC communicates with the auditory cortex (a primary hearing centre in the brain) to see whether it’s possible to strengthen the connection and improve hearing ability.
Their findings were published in Current Biology on July 11, 2024.
“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,” said senior author, University of Maryland Biology Assistant Professor Melissa Caras.
“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.”
To closely examine the brain circuitry involved in the hearing process, the researchers turned to gerbils whose basic hearing system is similar to that of humans.
They were exposed to sound patterns in two different contexts. In one, they listened to sounds passively without needing to do anything. In the other, they 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 orbitofrontal cortex 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 behaviourally relevant sound.
“In terms of a more human-oriented analogy, it would be as if I told you to suddenly pay attention to your refrigerator humming in the background,” Caras explained. “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.
“We’re just beginning to understand how the brain fine tunes hearing sensitivity in response to sudden shifts in behavioural contexts.
“This work is paving 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 added.
The auditory pathway, tracing the journey of sound information from the ear to the brain’s auditory cortex. The study suggests the orbitofrontal cortex plays a central role in helping the auditory cortex adapt to changing contexts or situations. Image: Pungu X/stock.adobe.com
