Overview
- Researchers used in vivo fiber photometry in rats to show that eating nutrient-rich food causes medial septum neurons to release acetylcholine in circuits that connect to the hippocampus, a brain region essential for forming new memories.
- Interrupting communication along the vagus nerve stopped the eating-related rise in acetylcholine and made rats worse at remembering where food had been located, demonstrating a causal gut-to-brain link for memory encoding.
- The effect tracked nutritional value rather than sweet taste alone, with calorie-rich sugar or fat triggering the pathway but low-calorie sweet solutions failing to do so.
- Rats given a high-fat, high-sugar ‘Western’ diet early in life showed long-lasting weakening of this vagus–hippocampus signaling and poorer food-location memory even after diet improvement.
- The study was peer reviewed and funded by NIH and other grants, and researchers say the findings raise possibilities for vagus-targeted approaches to human cognitive decline while noting that translation from rodents to people remains unproven.