A group of researchers has uncovered a memory system in the brain that is dedicated to food, shedding light on its essential role in overeating and diet-related obesity. They identified a specific set of neurons in the brains of mice that retain memories linked to sugar and fat, which significantly affect their eating behavior and weight.
Can our recollections shape our eating patterns and the amounts we consume? A groundbreaking study from the Monell Chemical Senses Center has confidently concluded with a “Yes.” Conducted by Dr. Guillaume de Lartigue, an Associate Member at Monell, this research successfully pinpointed the brain’s food-centric memory system and its association with overeating and obesity caused by diet.
In a report published in Nature Metabolism, the research team outlined a specific neuron cluster in the mouse brain that stores memories connected to sugar and fat, which profoundly influences their food intake and body weight. “In today’s society, we are constantly bombarded with advertisements and environmental signals that trigger memories of enjoyable food experiences,” Dr. de Lartigue remarked. “It’s significant that we’ve isolated a specific set of neurons within the hippocampus that not only help form these food-related memories but also affect our eating behaviors. This connection could have a major impact on body weight and metabolic health.”
These neurons encode where nutrient-dense foods can be found, providing a type of “memory trace,” especially for sugar and fat. When these neurons are silenced, mice exhibit a lowered capacity to remember experiences related to sugar, leading to decreased sugar intake and preventing weight gain, even when on diets that usually cause excessive weight gain. Conversely, reactivating these neurons enhances food-related memory, resulting in increased consumption, demonstrating how memories of food can determine eating habits.
These findings introduce two novel concepts: first, that particular neurons in the brain are responsible for storing memories about food, and second, that these memories directly influence our eating quantities. “While it’s common to recall pleasurable food encounters, it was generally believed that such memories had little impact on actual eating behavior,” Dr. de Lartigue explained. “The most astonishing discovery is that suppressing these neurons can halt weight gain, even when diets are high in fat and sugar.”
The Often Overlooked Influence of Memory
Memory is typically not seen as a major driving force behind food intake; however, this study clearly shows the connection between memory and metabolism. What sets this discovery apart from other memory studies is its significance to metabolic health. Removing sugar-responsive neurons from the mice’s hippocampus not only disrupts memory but also reduces sugar consumption and prevents weight gain, even when subjected to high-sugar diets. This establishes a direct link between certain brain circuits related to memory and metabolic health, a relationship that has largely been overlooked in obesity research.
“Hippocampal memory systems have evolved to help animals find and remember crucial food sources for survival,” stated Mingxin Yang, the first author and a Ph.D. student at the University of Pennsylvania in Dr. de Lartigue’s lab. “In our current world, where food is plentiful and cues are everywhere, these memory circuits can become activated, encouraging overeating and contributing to obesity.”
Independent yet Specific Circuits
Another crucial finding indicates that food-related memories are highly specific. Neurons that respond to sugar solely encode and influence memories associated with sugar, while those triggered by fat focus exclusively on fat. These neurons do not alter memories related to other activities, like spatial memories not connected to food.
“The specificity of these circuits is fascinating,” Dr. de Lartigue noted. “It emphasizes how finely tuned the brain is to associate food with behavioral responses, allowing animals to differentiate between different nutrient sources in their environment.” We possess distinct neurons that encode memories for fat-rich and sugar-rich foods separately. This separation likely evolved because in nature, foods rarely contain both fat and sugar, the researchers propose.
Potential Strategies for Addressing Obesity
The knowledge gained from this research may lead to new strategies for combating overeating and obesity. By concentrating on the hippocampal memory circuits, there is potential to disrupt the memory triggers that motivate the intake of unhealthy, high-calorie foods.
“These neurons are integral in linking sensory inputs to food consumption,” Dr. de Lartigue emphasized. “Given their ability to influence both memory and metabolism, they represent promising targets for obesity intervention in our food-abundant environment.”
This joint research included contributions from the University of Pennsylvania and the University of Southern California, receiving funding from the National Institutes of Health and the American Heart Association.
