Nov. 7, 2019 — The holidays are a time for many families to break bread together around the dinner table. But it’s also when many people get another scoop of mashed potatoes or grab a second piece of pie.
Indulging more than usual during holidays such as Thanksgiving can happen because of the way people use of all of their senses, said Lindsey Macpherson, a UTSA assistant professor of biology who specializes in sensory neuroscience.
“Eating is a multisensory experience. You engage pretty much all of your senses when you’re enjoying a meal, especially if you’re enjoying a meal among family,” Macpherson said. “You can see all these different foods. You can smell them. When you eat them, there’s the taste, but there’s also the texture.”
An experience is created when in a party atmosphere surrounded by the sights and sounds of the holidays, Macpherson said.
“When you have an exciting holiday meal, you’re engaging with other people and have many different courses,” she explained. “You’ve had several savory things that taste different, and still you feel like, ‘I still have room for a slice of pie, right?’ Those new flavors, like you get with a dessert, contribute to overeating at these lavish meals because essentially you’re reexciting your taste buds.”
Macpherson added that accessibility of nutritious and energy-rich foods also contributes to holiday overeating.
“We don’t have to go out and hunt to get our food. We can go to the grocery store and get whatever we want,” she said. “We definitely have an evolutionary drive to consume food that’s nutritious and highly energy-rich. We haven’t quite evolved far enough to curtail that. We have a long history of trying to take advantage of eating energy-rich foods, so we still have that drive to do so.”
The Macpherson Lab at UTSA investigates the sense of taste and the molecules, cells and circuits involved in chemosensation from the tongue and gut to the brain. The lab researches the different interactions of chemicals in food within the digestive tract, which Macpherson said she hopes can help with obesity and overeating in the future.
“Fairly recently people have identified taste receptors expressed within chemosensory cells in the gut, but we don’t know exactly what they’re doing,” she said. “My lab is looking within the gut and what chemicals activate those receptors but also what signals are processed within the gut.”
Macpherson believes the vagus nerve, which runs from the brain to the abdomen, plays a major role in signaling between the gustatory system, the stomach and the intestines and then back to the brain to give us an idea what types of foods we have eaten and how to process that food in the best way.
However, it’s not clear which circuits are used. Macpherson’s team is attempting to determine what neurons within the vagus nerve are activated by different types of chemicals within the digestive system and what signals are being mediated, such as the ability to digest better or reject food.
“If we can identify different neurons that are responsible for signaling different things, we might be able to target those neurons, activate them and tell our bodies, ‘Oh, you’ve had enough to eat. You should stop eating now,’” Macpherson said. “We hope that will be able to combat obesity. Or if you take a dash of that secret, unknown chemical along with your food, you might feel fuller more quickly. And that might help curtail overeating.”