Improved neuroplasticity speeds up hearing in cochlear implant wearers

A new study in deaf rats shows that cochlear implants can effectively restore hearing loss by activating the brain’s natural ability to adapt to new situations, known as neuroplasticity. The researchers say the study may help explain why some implant recipients respond better to treatment than others.

Unlike hearing aids, which amplify, balance, and sharpen incoming sounds, cochlear implants send electrical signals representing sounds directly to the brain. Unfortunately, figuring out what the signals mean takes time. Some cochlear implant users begin to understand speech duration after receiving their device, while others take months or years to figure it out. The mechanisms that determine how quickly the brain can adapt to implants are unknown.

A new study in rats led by researchers at NYU Langone Health – was published online Dec. 21 in the journal. Nature— evaluated whether stimulating the locus coeruleus, a major site of neuroplasticity deep in the mammalian brainstem, would improve the speed at which people learn to use devices. Within just three days of receiving the implants, rodents given an additional boost were shown to be able to effectively complete tasks requiring precise hearing. It took a person up to 16 days to do so.

Our findings suggest that differences in neuroplasticity, particularly in parts of the brain such as the locus coeruleus, may help explain why some cochlear implant users improve faster than others. suggests.”

Erin Glennon, PhD, first author of the study, neuroscientist, medical student at NYU Grossman School of Medicine

In a previous study, the researchers found that electrically stimulating the locus coeruleus in rodents increased neuroplasticity and altered the way the brain’s auditory system represents sounds. But according to Dr. Glennon, this new study is the first to show that stimulating this brain region can improve hearing in cochlear implant wearers.

For the study, the study authors trained rats with normal hearing to press a button after hearing a particular sound and ignore the button if they heard another sound. Once deaf, the rats were unable to complete the task. They were then given cochlear implants and retrained to rely on the device to perform the same tasks.

Among its findings, this study showed that locus coeruleus activity changes dramatically as rats learn to use implants. Initially, brain regions were most active when animals received food after hearing the sound and pressing the correct button. Instead, brain activity peaked when the sound was heard, as it learned to associate pressing the button with receiving the reward. Notably, the faster this change, the faster the rats consistently succeed on the task.

“Our results suggest that improving neuroplasticity in the locus coeruleus may accelerate and enhance the efficacy of cochlear implants. NYU Langone Physiology.

Dr. Froemke says the team next plans to explore ways to stimulate regions of the human brain that don’t require invasive surgery. Dr. Froemke is also Professor of Otolaryngology – Head and Neck Surgery at NYU Langone.

“Since our goal is to activate the locus coeruleus, we need to determine what non-invasive mechanisms can be used to trigger brain regions,” said the study’s co-lead author. said Dr. Mario A. Svirski, Noel L. Cohen Professor of Hearing Sciences. Otolaryngology – Head and Neck Surgery.

Dr. Svirsky, who is also a professor in the Department of Neuroscience and Physiology, said rat hearing was tested using simple sounds in a simple task, whereas humans need to respond to subtle speech patterns in noisy environments. I warn you. Further research is needed on other brain regions that may be involved, he says.

Funding for this study was provided by National Institutes of Health grants F30DC017351, T32GM007308, R01DC003937, R01DC012557, P30CA016087, and P41EB017183. Additional financial support was provided by NYU vendor Cochlear Ltd. Cochlear Ltd. also sells equipment and technical support to NYU Langone. The terms of these agreements are governed by the policies of the healthcare system.

In addition to Dr. Glennon, Dr. Froemke, and Dr. Svirsky, other investigators include Dr. Youssef Z. Wadghiri, Associate Professor of Radiology at NYU Langone. Dr. Silvana Valtcheva, Principal Investigator, University of Cologne, Germany. She is Angela Y. Zhu, M.D., Ph.D., Assistant Professor of Clinical Ophthalmology at the Bascom Palmer Eye Institute in Miami.