Can memory influence what and how much we eat? A groundbreaking study conducted by the Monell Chemical Senses Center and published in Nature Metabolism has answered this question with a resounding “Yes.” Led by Dr. Guillaume de Lartigue, the research team identified, for the first time, the brain’s food-specific memory system and its direct involvement in overeating and diet-induced obesity.
The research focused on a specific population of neurons in the mouse brain, found in the hippocampus, that encode memories for sugar and fat. These memories significantly impact food intake and body weight. Dr. de Lartigue explained, “In today’s world, we are constantly bombarded with advertisements and environmental triggers designed to remind us of pleasurable food experiences. What’s surprising is that we’ve pinpointed a specific population of neurons in the hippocampus that not only forms these food-related memories but also drives our eating behavior. This connection could have significant implications for body weight and metabolic health.”
These neurons create “memory traces” of nutrient-rich foods, particularly sugar and fat, by encoding their spatial location. Silencing these neurons impairs an animal’s ability to recall sugar-related memories, reducing sugar consumption and preventing weight gain, even when exposed to a diet that typically promotes excessive weight gain. Conversely, reactivating these neurons enhances food-related memory, leading to an increase in consumption. This provides compelling evidence that food memories play a direct role in influencing eating behavior.
While memory’s influence on eating behavior has been studied before, this research reveals a direct connection between food-related memories and metabolism, an area largely overlooked in obesity research. “Memory systems in the hippocampus evolved to help animals locate and remember food sources critical for survival,” explained Mingxin Yang, a doctoral student at the University of Pennsylvania. In modern environments, where food is abundant and ubiquitous, these memory systems may drive overeating, contributing to obesity.
By deleting sugar-responsive neurons in the hippocampus, the researchers not only disrupted memory but also reduced sugar intake and protected against weight gain, even when animals were exposed to high-sugar diets. This highlights the essential role certain brain circuits play in controlling both memory and metabolic health.
One of the most fascinating aspects of this research is the specificity of the neurons involved. The neurons responsive to sugar memories only encode and influence sugar-related intake, while those responsive to fat memories solely impact fat intake. These neurons do not affect other types of memory, such as spatial memory for non-food-related tasks.
Dr. de Lartigue noted, “The specificity of these circuits is fascinating. It underscores how finely tuned the brain is for linking food to behavior, ensuring animals can differentiate between various nutrient sources in their environment.” The discovery that the brain has separate systems for encoding sugar-related and fat-related memories may have evolved because, in nature, foods rarely contain both sugar and fat.
The findings of this study open new avenues for addressing overeating and obesity. By targeting the hippocampal memory circuits, it might be possible to disrupt the food-related memory triggers that drive the consumption of unhealthy, calorie-dense foods. “These neurons are critical for linking sensory cues to food intake,” Dr. de Lartigue explained. “Their ability to influence both memory and metabolism makes them promising targets for treating obesity in today’s food-rich world.”
This study was a collaboration with researchers from the University of Pennsylvania and the University of Southern California, supported by the National Institutes of Health and the American Heart Association.
The implications for metabolic health and obesity treatments are profound, as disrupting the memory circuits connected to specific foods could potentially offer a strategy to reduce overeating and obesity in a world where food is often in excess.
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