Researchers identify “food memory” neurons in lab rats that could explain why forgetting to eat lunch leads to overeating. Scientists have discovered a specific group of brain cells that can store memories of meals, encoding not only what was eaten but also when it was eaten. The findings, published in Nature Communications, could explain why people with memory problems often overeat and why forgetting a recent meal can trigger excessive hunger and lead to eating disorders. In addition, it also provides new strategies for treating obesity by improving memory related to food intake.
“Meal Engrams”
During eating, neurons in the ventral hippocampus area of the brain become active and form what the research team calls “mealtime engrams” – special memory traces that store information about the experience of food consumption. While scientists have long studied engrams for their role in storing memories and other experiences in the brain, the new study identified engrams that are specifically responsible for food experiences.
“An engram is the physical trace that a memory leaves in the brain,” explains Scott Kanoski, professor of biological sciences in the USC Dornsife College of Letters, Arts and Sciences and corresponding author of the study. “Meal engrams function like sophisticated biological databases that store different types of information, such as where you ate and when you ate.”
When Distracted, the Brain Cannot Properly Catalog the Eating Experience
The discovery is directly relevant to understanding eating disorders in humans. Patients with memory disorders, such as dementia or brain injuries that impair memory formation, often eat several meals in rapid succession because they cannot remember having eaten. In addition, eating – such as mindless snacking in front of the TV or while scrolling on a cell phone – can impair memory of meals and contribute to overconsumption.
Based on the results of the experiment, food engrams are formed during short pauses between bites, when the brains of lab rats are naturally aware of the eating environment. These moments of attention allow specialized neurons in the hippocampus to integrate multiple streams of information. Kanoski said it is reasonable to assume that the human brain undergoes a similar phenomenon. When a person’s attention is focused on something else – the smartphone or the TV – these crucial encoding moments are impaired. “The brain can’t properly catalog the eating experience,” said Lea Decarie-Spain, a postdoctoral researcher at USC Dornsife and first author of the study, “leading to weak or incomplete eating engrams.”
Mechanism of “Food Memories” Could Help Develop New Approaches for Treating Obesity
The research team used advanced neuroscience techniques to monitor the brain activity of laboratory rats during eating, providing the first real-time insight into the formation of food memories. Food memory neurons are different from brain cells involved in other types of memory formation. When the researchers selectively destroyed these neurons, the lab rats showed impaired memory for the locations where they had found food, but retained their normal spatial memory for non-food-related tasks, suggesting a specialized system for processing information related to meals. The study found that the neurons for food memories communicate with the lateral hypothalamus, a brain region that has long been known to control hunger and eating behavior. When this connection between the hippocampus and hypothalamus was blocked, the lab rats ate too much and could not remember where they had eaten their meals.
According to the researchers, these findings could ultimately lead to new clinical approaches for the treatment of obesity and support better weight management. Current weight loss strategies often focus on restricting food intake or increasing physical activity, but the new research suggests that improving food memory formation could be just as important.