Gut-Brain Connection May Determine Which Experiences Become Lasting Memories: Study - Video

Signals from the stomach may help the brain decide which food-related experiences are worth remembering, according to a new study published in Nature Communications. Researchers found that nutrient signals traveling from the gut to the brain through the vagus nerve play an important role in memory formation, while long-term consumption of unhealthy diets may weaken this communication.

Scientists at the USC Dornsife College of Letters, Arts and Sciences studied how the vagus nerve, which connects the digestive system and the brain, influences learning and memory.

In experiments involving rats, eating nutrient-rich foods increased the release of acetylcholine, a neurotransmitter essential for learning and memory, in neurons connected to the hippocampus, the brain's memory center. However, when communication through the vagus nerve was disrupted, acetylcholine levels no longer increased after eating, and the animals performed worse on tasks requiring them to remember where food had previously been found.

The researchers also discovered that the brain responded to the nutritional value of food rather than simply its sweet taste. Rats consuming foods rich in sugar or fat showed strong activation of memory-related brain pathways, whereas animals given sweet-tasting, low-calorie or non-caloric liquids did not produce the same response.

However, repeated exposure to high-fat and high-sugar diets appeared to have the opposite long-term effect. Rats fed unhealthy diets early in life later showed weaker communication between the gut and the hippocampus, even after returning to a healthier diet. They also demonstrated poorer memory performance when locating food.

The findings may help explain why obesity, poor diet, and metabolic diseases have been linked to cognitive decline. Because reduced acetylcholine signaling is also one of the earliest changes seen in Alzheimer's disease, the researchers suggest that therapies targeting the gut-brain connection, including vagus nerve stimulation, may one day help support memory.

REFERENCE: Logan Tierno Lauer, Anna M. R. Hayes, et al.; The vagus nerve promotes memory in rats via nutrient-induced septo-hippocampal acetylcholine signaling. Nature Communications, 2026; 17 (1) DOI: 10.1038/s41467-026-73896-2