A scientist explores the mysteries of the gut-brain connection

If you were asked where the human body’s nervous system is located, you’d probably answer “the brain” or “the spinal cord.” But besides the central nervous system, which consists of those two organs, our bodies also contain the enteric nervous system, a two-layer lining with more than 100 million nerve cells that spans our guts from the esophagus to the rectum. The enteric nervous system has been called “the second brain,” and it’s in constant contact with the one in our skull. That’s why just thinking about food can lead your stomach to start secreting enzymes, or why giving a speech can lead to your feeling queasy.