Stomach helps the brain form memories

The experiments were conducted on rats. The researchers noticed that after consuming a nutritious meal, the neurons that transmit signals to the hippocampus (a region of the brain that is critical for learning and memory) released more acetylcholine, a neurotransmitter that supports the formation of memories and helps the brain record new experiences.

The key role here is played by signals from the gut: when the scientists blocked the transmission through the vagus nerve, the acetylcholine spike disappeared. At the same time, the animals’ performance in memory tests deteriorated, and the rats had difficulty recalling where they had previously found food.

However, it was discovered that the memory system was not simply responding to the pleasant taste, but rather to the nutritional value of the food. Rats that consumed high-sugar or high-fat foods exhibited significant memory-related activity. In contrast, sweet but low-calorie or non-caloric liquids did not have the same effect. According to the authors, this mechanism may have evolved to help animals remember where to find valuable sources of nutrients.

Although high-fat and high-sugar diets elicited a strong short-term response in the memory system, consistent consumption of such foods over time impaired the ability to form memories.

Rats that were fed a high-fat and high-sugar diet from an early age later displayed a weakened connection between the gut and the hippocampus. Even after switching to a healthier diet, they still had reduced memory-related responses and performed worse on tasks involving remembering the location of food.

These findings may explain why obesity, metabolic disorders (such as diabetes), and unhealthy diets are associated with cognitive decline: regular consumption of poor-quality food may disrupt the connection between the gut and the brain.

Additionally, this discovery has potential implications for the management of neurodegenerative diseases. The fact is that a decrease in acetylcholine signaling in the hippocampus is one of the earliest neurochemical changes in Alzheimer’s disease. Since the study has shown that this system is enhanced by gut signals through the vagus nerve, new avenues for therapy, such as vagus nerve stimulation, are opening up. Additionally, methods that improve gut health may also be potentially beneficial.

However, it is too early to directly apply these findings to humans, as further research is needed to confirm that the mechanisms work similarly in humans. Nevertheless, this work once again highlights the close relationship between the gut and the brain.