Oct 08, 2025
Christoph Thaiss
The Gut-Brain Axis

The gut-brain connection is a key part of how the brain forms a picture of the rest of the body, a phenomenon known as interoception, explained Christoph Thaiss, PhD, an assistant professor of pathology at Stanford Medicine.

Through direct signals from the vagus nerve, which connects the brain and the gut, as well as through molecules secreted into the bloodstream from our gut microbes and immune cells that traffic from the gut to the rest of the body, our brains and our digestive tracts are in constant communication. And when that communication goes off the rails, diseases and disorders can result.

It affects your mood, your sleep, even your motivation to exercise. There’s convincing evidence that it’s the starting point for Parkinson’s disease and could be responsible for long COVID’s cognitive effects. And it sits about 2 feet below your brain.