After years of work, cognition and neuroscience doctoral student Hailey Welch is—for the first time—the lead author of a study published in an academic journal, a paper appearing in Cell Reports, which examined the role of the vagus nerve’s branches in digestive signaling.
The goal of Welch’s research is to learn more about the vagus nerve‘s role in the forming of dietary habits. The vagus nerve includes left and right branches. Earlier research in the Motor and Habit Learning Lab of Dr. Catherine Thorn, associate professor of neuroscience in the School of Behavioral and Brain Sciences and the corresponding author of the Cell Reports study, indicates that those two sides have different functions.
“We know that the vagus nerve transmits information about the nutritional and reward aspects of food from the gut to the brain,” Welch said. “What we are discovering is that such reward signaling is lateralized—mainly right-sided.”
The human drive to consume energy-dense, high-fat and high-sugar foods has persisted through millennia. In the modern world, with easy access to so many foods high in both fat and sugar, this craving can lead to obesity and metabolic disorders, Welch said.
Her research in the study charted the molecular and functional profiles of sensory neurons in the vagus nerve using genetic sequencing, imaging and functional assays. The work, conducted in rodents, provides a potential explanation for why right-sided vagus nerve signaling activates the release in the brain of dopamine, known as the “feel-good” hormone.
“We found that the right vagus nerve includes a unique population of sensory neurons consistent with sensing signals from the digestive system. There are about half as many of these neurons on the left side,” Welch said. “This supports the idea that the right vagus nerve is more involved in sensing nutritional information and reinforcing dietary behaviors.”
Building on the findings, the proposed experiments would attempt to narrow down this role to specific nerve cells within the right vagus nerve.
“We’re currently working on techniques to lesion these specific neurons to learn the effect on food preferences,” said Welch, who is also a Eugene McDermott Graduate Fellow at UT Dallas. “We’re hoping that introducing a specific lesion will allow us to learn more about the possibly lateralized development of preference for high fat diets.”
Thorn, whose research focuses on the neuroscience of motor-skill learning, said that Welch’s research on the vagus nerve has implications for improving treatments not only for obesity or metabolic diseases, but possibly movement disorders, depression and substance abuse.
“We know that there are differences between the right and left sides in how the vagus nerve encodes these reward signals, and Hailey has found a possible molecular underpinning for such side-specific functions,” said Thorn, who is also a Fellow, Eugene McDermott Distinguished Professor. “Food can be very rewarding, and if we can tap into the body’s natural mechanisms for encoding these rewarding properties of food, we may be able to improve motivation and learning across a range of contexts.”
Growing up in Tulsa, Oklahoma, Welch said that by early high school, she knew she wanted to be a neuroscientist, and she listened to podcasts to expand her knowledge of the topic. At the University of Oklahoma, she studied chemical biosciences and performed research on the relationship between iron deficiency and dopamine. A self-described “foodie” with a love for cooking and trying new foods, Welch was initially drawn to UT Dallas for graduate studies for its strength in pain research. But once she joined Thorn’s lab, she knew she had found her niche.
“Continuing this gut-brain research is a perfect fit. It’s not what I foresaw myself doing, but it makes total sense, and I love it so much,” she said. “Science is hard, and experiments generally don’t work the first time, but the passion for figuring out what’s going on is the thing that keeps me going.”
Thorn added, “Hailey is using many different approaches to answer this massively complex question of how gut-brain circuits can impact decision-making. Her research is taking the lab in exciting new directions.”
More information:
Hailey F. Welch et al, Molecular and functional asymmetry in Cckar-expressing vagal sensory neurons, Cell Reports (2025). DOI: 10.1016/j.celrep.2025.116507
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