One of the twelve pairs of cranial nerves in the human body, the vagus nerve connects the brain stem to the body, transmitting information from the brain to the major organs and other tissues.

Vagus nerve stimulation: A neuromodulation treatment that involves a small implant that electrically stimulates the vagus nerve, which runs from the brain stem to the abdomen. It is mostly used to treat epilepsy but is also being investigated as a potential treatment for depression, bipolar disorder, and Alzheimer’s disease.