Food plays an important role in many important moments in our lives, whether it’s grand occasions, like the wedding banquet, or smaller ones, like the weekend barbecue, the lunch date, or the family dinner time.
A new study suggests good food might be more than a mere accessory to those special occasions: it might even directly boost the brain’s memory-making machinery, helping to store away those important memories.
Biologist Scott Kanoski, of the University of Southern California, led a study recently published in Nature Communications that suggests food can quite literally impact the formation of memory, via a chain of nerve signaling.
In a series of rat experiments, Kanoski and team discovered that after a nutritious meal, a signal is sent up the vagus nerve, from the gut to the brain.
That signal reaches neurons in the medial septum, a brain region that impacts activity in the hippocampus.
Scientists already knew that memories are encoded in the hippocampus when medial septum neurons release a neurotransmitter called acetylcholine.
But they didn’t know that what was going on in the gut – as ‘reported’ to the brain by the vagus nerve – could impact acetylcholine release all the way up in the medial septum.
It turns out that, at least in rats, memory-making is very much influenced by what’s going on in the gut.
The researchers used fiber photometry to watch the activity of certain brain cells as rats were fed different diets. In one experiment, some rats were given a solution with fat or sugar, while others were given a similarly sweet-tasting solution that was low-calorie or contained no calories at all.
The animals that ate fats and sugars had stronger memory-related activity in their brains, even after eating. This suggests that consuming calories, not the act of eating or the taste of food, is what affects this gut-brain chain of memory signaling.
“Eating behavior dynamically increases hippocampus acetylcholine release, and these levels remain elevated after a meal,” Kanoski and team write.
“These effects are eliminated by either vagal afferent neuron ablation or medial septum acetylcholine neuron deletion.”
In other words, when the researchers tampered with the lines of communication, this specific relationship between food and acetylcholine release disappeared.
“We think the mechanism likely evolved to help animals remember vital information about food sources,” says first author of the study, biologist Logan Lauer.
And yet, high-fat and high-calorie diets didn’t always translate to better memory.
When rats were given a Western ‘junk food’ diet of high-fat, high-sugar chow along with potato chips, peanut butter cups, and high-fructose corn syrup early in life, this specific acetylcholine signaling system was weakened.
Even when they were fed healthier foods again later in life, they struggled with memory tasks.
Just because something works a certain way in a rat doesn’t mean it will be the same in a human, although as mammals, our shared evolutionary history means there is often a fair bit of overlap.
Also, the study was conducted only in male rats, which makes its findings even less broadly applicable.
With further research to address those limitations, these findings could be useful in finding ways to improve gut-brain signaling in humans.
frameborder=”0″ allow=”accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share” referrerpolicy=”strict-origin-when-cross-origin” allowfullscreen>“The disruption of acetylcholine signaling in the hippocampus is one of the earliest neurochemical changes in Alzheimer’s disease,” says Kanoski.
“By revealing that this system is boosted by gut signaling from the vagus nerve, novel therapeutic targets could leverage this information to explore vagus nerve-based approaches, such as vagus nerve stimulation.”
Related: Ultra-Processed Foods May Be Quietly Affecting Your Brain’s Ability to Focus
Sometimes called a ‘pacemaker for the brain’, vagus nerve stimulation can provide lasting benefits for many people with depression and is an approved treatment for epilepsy and stroke rehabilitation.
It remains to be seen whether the treatment could also affect memory-making in humans; trials are underway, and a handful of studies suggest it may prevent memory from worsening in early-stage Alzheimer’s, or even improve it.
The research was published in Nature Communications.
This article was fact-checked by Clare Watson and edited by Clare Watson. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
