Have you ever wondered why some people love to end a good meal with a sweet dessert, while others are the bane of savory appetizers? What do our food preferences depend on? Trying to answer these questions, a new investigation has found that there is a strong relationship between the food we eat during the first years of life, and our culinary tastes when we reach adulthood, and that this relationship depends, specifically, on the effects that about the brain our first experience with food.
The study has been carried out by researchers from Stony Brook University and has identified the neural basis that regulates preferences for our favorite foods, providing new data on the relationship between brain function and nutrition, as well as highlighting the importance of early exposure to different flavors. Their results have been published in Science Advances.
As the biology of the taste system is similar in all mammals, the researchers used groups of mice, which were exposed – either as weanlings (early exposure) or as adults (late exposure) – to a variety of flavors for a week, and thereafter. the animals returned to eating their usual diet, which was balanced but tasteless. In addition, they bred another group of mice on the blander regular diet for comparison. They thus discovered that the development of neural circuits and preference for taste are influenced by all aspects of the taste experience: sensations in the mouth, smell, the gut-brain axis.
“Understanding the developmental neural circuitry for tastes will contribute to our understanding of food choices and eating disorders”
“Our research is aimed at evaluating whether and how taste experience and diet influence brain development. This study shows that the taste experience has fundamental effects on the brain. The next steps will be to determine how different diets, such as one that is high in fat, or one that is high in sugar or salt, can influence taste preferences and neural activity,” said Arianna Maffei, lead author and professor in the Department of Neurobiology and Behavior.
How a preference for sweet tastes develops
Several weeks after the mice were exposed to the variety of flavors, the animals’ preference for a sweet solution compared to water was assessed, and adult mice that had experienced a variety of flavors early in life showed a higher preference. by sweet tastes compared to the control group. However, mice exposed to the same variety of tastes as adults did not show such a sweet preference, indicating that taste experience influences preference, but only if it occurs over a restricted period of time. .
The researchers also recorded the activity of neurons in the gustatory cortex, an area of the brain involved in taste perception and decisions about eating or refusing food, and this activity showed that change in sweet preference was associated with differences in the activity of inhibitory neurons in adult mice, so they wondered if manipulating these inhibitory neurons in adulthood might modify sensitivity to the experience of taste.
To verify this, they injected a substance into the taste cortex that breaks down the perineuronal networks, which are networks of proteins that accumulate around inhibitory neurons in the early stages of life, and that play a fundamental role in limiting plasticity, the ability to change in response to stimuli at inhibitory synapses.
When exposed to the flavor variety, adult mice without perineuronal networks in the taste cortex showed a change in sweet preference similar to that of the group exposed early in life. This manipulation “rejuvenated” inhibitory synapses in the taste cortex and restored plasticity in response to taste experience, confirming the importance of maturation and plasticity in inhibitory circuitry for the development of taste preference in the experimental model. .
The authors say that, although the study was done in mice, the findings provide very useful information about the fundamental biological aspects of taste experiences that extend beyond animal models and humans. “The development of taste preference requires a complete taste experience,” says Maffei. “This includes the detection of taste in the mouth, its association with smell, and the activation of gastrointestinal sensations. All these aspects influence the activity of brain circuits, favoring their healthy development”.
Maffei explains that humans often prefer the food of our childhood and that there are important cultural aspects to our taste experience. He also notes that various neurodevelopmental and neurodegenerative disorders are frequently associated with hypersensitivity or hyposensitivity to taste stimuli, suggesting links between taste and brain function in health and disease. “Expanding our knowledge of the developmental neural circuitry for tastes, as studies such as this do, will contribute to our understanding of food choices, eating disorders, and diseases associated with brain disorders,” she concludes.
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