Scientists talked about the mechanism of formation of food preferences
The first cup of coffee may seem too bitter, but over time you start to like the taste. Such changes in food preferences are not only related to habit: the body learns to associate the taste of foods with their nutritional value. Scientists have discovered a mechanism that helps the brain form such associations using signals from the gut. How this system works and why it affects our tastes is described in the Izvestia article.
A slow signal from the intestine
Researchers from the University of California, San Francisco, have discovered a dopamine pathway that helps the brain connect the taste of food with the intake of nutrients. The work was published in the journal Nature.
Zachary Knight, Professor of physiology and senior author of the study
We have shown that it is this slow dopamine system that makes us learn to love certain foods over time, and now we can see where and how this happens.
Unlike the rapid dopamine signals that occur, for example, at the sight of your favorite food, the discovered mechanism is triggered after the intake of nutrients into the digestive system. Intestinal sensors detect sugar and fat, and then transmit the information to the brain. The signal increases gradually and may persist for several minutes.
How preferences are formed
To study this process, the scientists injected sugar water or a milkshake-like liquid directly into the stomach of mice. This is how the researchers were able to separate the reaction to nutrients from the reaction to taste. After eating, they recorded a prolonged release of dopamine in the anterior basolateral amygdala, an area of the brain involved in processing emotions and forming memories.
Zachary Knight
We saw that this dopamine belongs to a different system, and we began to understand its role.
When the researchers blocked this pathway, the mice continued to eat normally, but stopped associating the new taste with calorie intake. In another experiment, the scientists artificially activated dopamine fibers after the animals tasted a calorie-free product. As a result, the mice began to prefer this taste.
Similar patterns have been found in humans. Dana Small, a psychologist from Yale University (the organization's activities are considered undesirable in the Russian Federation), reanalyzed an early PET study of 13 men and recorded the release of dopamine in the left side of the basolateral amygdala after the intake of nutrients. In a separate experiment involving 38 adults, fMRI showed increased activity in the same area after consuming glucose.
Is it possible to change tastes
In both mice and humans, the reaction was noticeably stronger in the left side of the basolateral amygdala than in the right. This surprised the researchers: neural circuits responsible for basic functions, including nutrition, are usually considered symmetrical. Scientists have yet to find out why the discovered mechanism mainly involves the left side of the brain.
The discovery gives researchers new opportunities to study eating habits. Knight also suggested that this mechanism could potentially be influenced by drugs that mimic the action of the hormone GLP-1. However, the team did not study their effects on the discovered dopamine pathway, so this relationship remains a hypothesis for now.
Zachary Knight
Understanding the stages between the discovery of nutrients in the gut and learning in the brain can allow us to fine-tune these processes to imperceptibly change our preferences for different foods.
So far, the study reveals one of the mechanisms of food preference formation, but it does not offer a ready-made way to change a person's tastes or eating behavior.
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