Mechanisms of action of vagus nerve stimulation (VNS)

In 1992, Dr Jake Zabara discovered in a canine model that repeated stimulation of the vagus nerve in the neck could stop seizures. Since that time, repeated stimulation of the vagus nerve has been FDA approved as an anticonvulsant. Zabara's work is built on a 50-year-old theme in the literature where scientists had sought to exploit the fact that the vagus nerve is composed of 80% afferent fibers. Thus vagus stimulation might potentially provide a 'window' into the brain. This manuscript reviews the basic science and brain imaging work done to date with VNS, attempting to understand how VNS affects the brain. This research is crucial to perfecting VNS as an anticonvulsant, and for determining other neuropsychiatric conditions that might be helped by VNS.