Summary: New research shows that stimulating the vagus nerve enhances perceptual learning, allowing animals to better distinguish between subtle sensory differences over time.
In this study, mice trained to discriminate between sounds improved further when the vagus nerve was stimulated, surpassing the performance plateau seen in unstimulated mice. This stimulation activates areas of the brain associated with attention, memory, and neuroplasticity, suggesting it may increase adaptability to new experiences. The findings suggest that vagus nerve stimulation may help improve sensory-based skills in humans, including adaptation to cochlear implants.
The researchers plan to further investigate this approach in humans, particularly to help people with hearing loss. This study highlights the potential of non-invasive techniques to promote learning and sensory adaptation.
important facts
Stimulating the vagus nerve enhanced the mice’s learning, allowing them to better recognize subtle differences. Stimulated mice showed increased neuroplasticity in the auditory cortex. The findings have the potential to improve learning and sensory adaptation in humans, especially mice with cochlear implants.
Source: New York University Langone
Just as musicians can be trained to better distinguish subtle differences in pitch, mammals can be trained to improve their ability to interpret hearing, vision, and other senses. This process, called perceptual learning, can be enhanced by activating key nerves that connect the brain to nearly every organ in the body, a new study in mice shows.
The study, led by researchers at New York University Langone Health, focuses on the vagus nerve, which carries signals between the brain, heart, digestive system, and other organs.
Experts have long studied targeting this nerve with gentle electrical pulses to treat conditions ranging from epilepsy and depression to post-traumatic stress disorder and hearing loss.
However, the results of such efforts have been mixed, and the underlying mechanisms that may lead to improved hearing have remained unclear until now.
To learn more about whether vagus nerve stimulation can promote perceptual learning, the researchers trained 38 mice to distinguish between musical tones. Initially, all animals performed better and made fewer mistakes over time.
However, while the untreated rodents reached their limit after approximately 1 week of training, the neurally stimulated rodents continued to improve at the task and on average improved on most tests compared to before the simulation. Errors decreased by about 10%.
Additionally, mice in this group made half as many errors as their counterparts on the most difficult assessment, which requires distinguishing between very similar sounds.
“Our findings suggest that activating the vagus nerve during training may push the limits of what animals, and perhaps even humans, can learn to perceive,” said the researchers. said Kathleen Martin, BS, author and graduate student at New York University’s Grossman Institute for Neuroscience. Faculty of Medicine.
In the second part of the study, the researchers evaluated how and where vagus nerve stimulation affects the brain. The results showed that the technique stimulated activity in the basal cholinergic forebrain, an area involved in attention and memory. When the researchers instead suppressed this region during neural activation, the rodents were unable to obtain any additional learning effects.
Additionally, the researchers found that vagus nerve stimulation increases neuroplasticity, a process that allows brain cells to adapt to new experiences and form memories, in the auditory cortex, the brain’s main hearing center. Showed. This may lead to long-term cellular changes that allow new skills to persist even after training, Martin said.
He notes that targeting the vagus nerve to enhance hearing has been controversial among experts, and previous studies in animals have failed to show significant improvements. .
The new study, published online Sept. 16 in the journal Nature Neuroscience, shows that the method may actually work, although results took longer to produce than the researchers originally expected. The authors say that this suggests that. This delay may occur in part because the electrical pulses used in the technique can distract laboratory animals and they may need time to adjust to the sensation, Martin said. added.
The authors point out that using vagus nerve stimulation to enhance hearing has potential uses far beyond maximizing musical ability. Perceptual learning is a key element in both understanding new languages and adapting to cochlear implants, a cochlear implant tool used to restore hearing loss. In particular, it often takes patients several months to get used to these devices, and many patients continue to struggle with conversation even after years of use.
“These results highlight the potential for vagus nerve stimulation to enhance hearing improvement with cochlear implants,” said study lead author Dr. Robert Froemke. “By promoting perceptual learning, this method could make it easier for implant recipients to communicate with others, hear approaching cars, and engage more effectively with the world around them. There is a sex.”
Froemke, the Skirball Professor of Genetics in the Department of Neuroscience and Physiology at New York University’s Grossman School of Medicine, said the electrical stimulators currently used to activate the vagus nerve are only a few centimeters in diameter and are used in outpatient settings. He says it can be implanted surgically. procedure. Some devices, such as those used to relieve migraines, are even less invasive and are simply applied to the skin of the neck.
According to Fromke, who is also a professor in the Department of Otolaryngology and Head and Neck Surgery at the New York University Grossman School of Medicine, the researchers tested vagus nerve stimulation in rodents with cochlear implants based on the following findings: The plan is to see if the functionality improves.
Professor Fromke, who is also a member of the New York University Langone Neuroscience Institute, said that because the vagus nerve is much larger and more complex in humans than in mice, the effects of stimulating the vagus nerve may be different and therefore in humans. It warns that further tests need to be carried out on the patient.
Funding: Funding for the study was provided by National Institutes of Health grant DC012557. Additional research funding was provided by the U.S. Department of Defense and the National Science Foundation.
In addition to Martin and Froemke, researchers from New York University Langone College who were involved in the study include Eleni Papadoyannis, Massachusetts, and Jennifer Schiavo, Ph.D.; Saba Shokat Fadai, Mississippi. Javon Issa, Bachelor of Science. Soomin Song, Ph.D. Sofia Orley Valencia, Bachelor of Science; Other study collaborators include Dr. Nesibe Temiz of the Friedrich Miescher Institute for Biomedical Research in Basel, Switzerland. Dr. Matthew McGinley, Baylor College of Medicine, Houston, Texas; and Dr. David McCormick of the University of Oregon, Eugene.
About this brain stimulation and learning research news
Author: Sheila Pollan
Source: New York University Langone
Contact: Shira Pollan – NYU Langone
Image: Image credited to Neuroscience News
Original research: Closed access.
“Stimulation of the vagus nerve recruits the central cholinergic system to enhance perceptual learning” (Kathleen Martin et al.) Natural Neuroscience
abstract
Vagus nerve stimulation recruits the central cholinergic system to enhance perceptual learning
Awareness can be refined through experience up to a certain limit. It is unclear whether perceptual limitations are absolute or can be partially overcome through enhanced neuromodulation and plasticity.
Recent studies suggest that peripheral nerve stimulation, particularly vagus nerve stimulation (VNS), can alter neural activity and enhance experience-dependent plasticity, but the central mechanisms recruited by VNS are unclear. is little understood.
Here we developed an auditory discrimination task for mice implanted with VNS electrodes. Applying VNS during behavior gradually improved discrimination ability beyond the level that could be achieved through training alone.
Two-photon imaging revealed that VNS induces changes in auditory cortical responses and activates cholinergic axons that project to the cortex. Anatomical and optogenetic experiments have shown that VNS can improve task performance through activation of the central cholinergic system.
These results highlight the importance of cholinergic modulation for the efficacy of VNS and may contribute to further refinement of VNS methodology for clinical conditions.
