Unlocking the neural basis of overeating

Does memory influence what and how much we eat? Breakthrough Monell Chemosensory Center A study linking food memory and overeating answered that question with a yes. A research team led by Monel Associate Dr. Guillaume de Lartigue has for the first time identified the brain's food-specific memory system and its direct role in overeating and diet-induced obesity.

Published in natural metabolismthey describe a specific population of neurons in the mouse brain that encodes sugar and fat memory, with profound effects on food intake and body weight. “In today's world, we are constantly bombarded with advertising and environmental cues designed to remind us of pleasurable food experiences,” says Dr. de Lartigue. “What was surprising was that we identified a specific population of neurons within the hippocampus. It not only forms these food-related memories but also drives our eating behavior. This relationship can have significant implications for weight and metabolic health. ”

These neurons encode memories of the spatial location of nutrient-rich foods and serve as “memory traces”, especially for sugars and fats. Silencing these neurons impairs the ability to recall sugar-related memories, reducing sugar consumption and preventing weight gain, even when animals are exposed to diets that lead to excessive weight gain. Conversely, reactivating these neurons strengthens food memory and increases consumption, demonstrating how food memory influences eating behavior.

These findings introduce two new concepts. First, there is evidence that specific neurons in the brain store food-related memories, and second, these memories directly influence food intake. “It's no surprise that we remember pleasurable eating experiences, but it has long been thought that these memories have little or no influence on eating behavior,” de Lartigue said. says. “What's most surprising is that inhibiting these neurons prevents weight gain, even in response to a diet high in fat or sugar.”

The underappreciated role of memory

Memory is often overlooked as a major factor in food intake, but this study shows a direct link between memory and metabolism. What sets this finding apart from other studies related to memory is its implications for understanding metabolic health. Deleting sugar-responsive neurons in an animal's hippocampus not only destroys memory, but also reduces sugar intake and prevents weight gain when the animal is exposed to a high-sugar diet. This highlights a direct link between specific brain circuits involved in memory and metabolic health, which has been largely overlooked in the field of obesity research.

“The hippocampal memory system evolved to allow animals to locate and remember food sources essential for survival,” said first author Minxin Yang, a doctoral student in de Lartigue's lab at the University of Pennsylvania. .

In modern environments where food is plentiful and cues are everywhere, these memory circuits can encourage overeating and contribute to obesity. ”

Minxing Yang, PhD student, University of Pennsylvania

Special yet independent circuit

Another important finding is that food-related memories are highly specific. Glucose-responsive neurons encode and influence only sugar-related memories and intake, whereas fat-responsive neurons influence only fat intake. These neurons do not influence other types of memory, such as spatial memory for tasks that do not involve food.

“The specificity of these circuits is interesting,” de Lartigue said. “This highlights how the brain is finely tuned to link food and behavior so that animals can reliably distinguish between different nutrient sources in their environment.” It has separate types of neurons that encode memories of sugar-rich foods and memories of sugar-rich foods. The authors speculate that these separate systems probably evolved because foods in nature rarely contain both fat and sugar.

Implications for obesity treatment

The findings open new possibilities for combating overeating and obesity. By targeting memory circuits in the hippocampus, researchers may be able to block memory triggers that encourage eating unhealthy, high-calorie foods.

“These neurons are important for linking sensory signals to food intake,” Dr. de Lartigue said. “Their ability to influence both memory and metabolism makes them promising targets for treating obesity in today's food-rich world.”

This collaboration was conducted with colleagues at the University of Pennsylvania and the University of Southern California, and was supported by the National Institutes of Health and the American Heart Association.