For more than 100 years, scientists have known that the vagus nerve carries signals between the organs and the brainstem. As part of the parasympathetic nervous system (rest & digest mode) the vagus regulates functions like heart rate, breathing, and digestion. But new studies have shown signals carried by vagal fibers climb beyond the brainstem, revealing a broad interoceptive network in the brain that interprets internal changes, anticipates the body’s needs, and sends commands to fulfill them.