We like to think of our brains as the ultimate commanders-in-chief, dictating each and every heartbeat and muscle twitch within our bodies.
But our loopy insides may have a lot more say than we realize.
“Not only does the brain send information to the gut, but the gut sends information to the brain,” said Michael Gershon, professor of pathology and cell biology at Columbia University. “And much of that we don’t yet understand.”
Gershon was one of nearly 200 scientists gathered at Duke last Friday for Gastronauts, a symposium exploring how our twisty, slimy guts and our twisty, slimy brains communicate with each other. By decoding the cellular and molecular messaging behind this gut-brain chatter, these researchers hope to gain insight into a wide array of modern health challenges, from obesity to Alzheimer’s.
Even if you sever all nerve connections between the brain and the gut, Gershon explained, your digestive tract will still carry on all that squeezing and acid-secreting necessary to digest food. The gut’s ability to ‘direct its own traffic’ led Gershon to dub the gut’s nervous system our “Second Brain.”
“The brain in the head deals with the finer things in life like religion, poetry, politics, while the brain in the gut deals with the messy, dirty, disgusting business of digestion,” Gershon said.
Our head brain and our gut brain talk to each other via long nerve fibers, such as a bundle of nerve cells called the vagus nerve that links the central nervous system to our abdominal organs, or via chemical signals, such as the neurotransmitter serotonin. Talks throughout the day delved into different aspects of these interactions – from how eating sugar can change our perception of taste to how the make-up of our gut microbiome might influence neural connectivity in the brain.
Duke professor Warren Grill presented his latest research on electrical stimulation of the vagus nerve. In projects led by graduate student Nikki Pelot and senior Eric Musselman, his group is building computer models to simulate the effects of electrical pulses on individual nerve cells within the vagus. These models might allow researchers to design devices to specifically block electrical signals going to the gut, a treatment that has been shown to help with obesity, Grill said.
And though we may think of the gut as the second brain, we should all remember that it came first, Duke professor Diego Bohórquez reminded the audience in the opening remarks.
“I like to say the gut is actually the first brain,” said Bohórquez. “If you go back to seafloor organisms, that was the first nervous system that was assembled.”