Our brain has a 'food memory' that controls hunger: this is how it works

Scientists have long suspected that memory influences our cravings, but the brain circuitry responsible for this behavior remained a mystery. And perhaps that's the case until now. A team of researchers at the University of California, Dornbirn claims to have unraveled this mystery by identifying the neurons that hold a "food memory," recording every detail of these meals: what type of food we ate and when we ate it.

This is suggested by experiments conducted with rats and mice, which suggest that the brain uses these food memories to help control hunger and eating behavior, and triggers a feeling of satiety after smelling food. This would be a revolution for obesity and weight control treatments.

These neurons are thought to be neurons in the ventral hippocampus (in the front of the brain) that fire during meals, forming mealtime engrams, specialized memory traces that store information about the experience of eating. It has long been known that engrams store different types of memories. This study is the first to identify engrams specifically linked to eating.

"An engram (or inscription) is the physical imprint that a memory leaves in the brain ," said Scott Kanoski, a professor of biological sciences in the USC Dornsife College of Letters, Arts and Sciences and corresponding author of the study published in the journal Nature . "Food engrams function as sophisticated biological databases that store various types of information, such as where and when a person ate."

When memory falters—as happens in dementia or after brain injuries— our brain can forget a recent meal and confuse hunger signals, leading us to eat multiple times in a short period of time. On the other hand, eating while distracted—whether glued to the television or mobile phone—makes it difficult for the brain to accurately record what we've eaten because it's so distracted, which can also lead to eating disorders stemming from somewhat careless eating. This is because the brain doesn't properly categorize the experience of eating when attention wanders, which poses a serious concern for anyone who eats with their phone, tablet, or TV in front of them. Your brain may struggle to remember not only how much you've eaten, but even that you've eaten at all, which can contribute to overeating.

And human data supports this idea. Remembering a recent lunch can reduce afternoon snacking by up to 30%. Our memories of meals not only record what we ate, but also set the internal clock that dictates when to eat again.

In experiments with rodents, when this memory weakened, meals occurred at shorter intervals, while reinforced engrams lengthened the wait until the next meal. These findings indicate that the brain uses memory to time hunger, not merely to make us feel full. In humans, this could explain why, when we eat distractedly, we feel hungry again almost immediately. If the brain hasn't properly registered the signal that we've eaten, hunger can return more quickly.

"We are finally beginning to understand that remembering what and when you ate is as crucial to healthy eating as the food choices themselves ," the authors add.

Scientists have long suspected that memory influences our cravings, but the brain circuitry responsible for this behavior remained a mystery. And perhaps that's the case until now. A team of researchers at the University of California, Dornbirn claims to have unraveled this mystery by identifying the neurons that hold a "food memory," recording every detail of these meals: what type of food we ate and when we ate it.