I first discovered the Vagus Nerve (VN) when I was researching how Parkinson's Disease begins in the gut: "Braak's Hypothesis" of the disease states that the problem spreads from its origins in the digestive tract to the brain, using the Vagus Nerve as the conduit. My interest was further piqued when I read that people who had had their VN severed via a vagotomy - a surgical "solution" for stomach ulcers - appeared to have significantly less likelyhood of developing PD.