Stimulation of the vagus nerve is thought to affect some of its connections to areas in the brain that are prone to seizure activity. It is a "Hot Topic" for research in areas of Depression, Obesity, Epilepsy, and is responsible for some phenomenal sensory and motor responses even without WLS.

Emotions running high? Feeling a lump at the back of your throat that you didn’t put there? That’s the Vagus Nerve at work. Can’t tickle yourself, except the roof of your mouth? (try it) Because when you try to tickle your armpit-The same nerves that perceive the tickle also "know that it’s coming," and thus the "surprise" aspect that allows "tickling" to occur have been preempted. But- Roof of the mouth? Different selective dumping of info prior to reaching the brain. That’s the Vagus nerve "sharing" some info with sensory and motor controls while "not telling others."

The Vagus nerve is known as a "mixed nerve" meaning it both receives input from the body and sends signals to various muscles and organs of the body. It is the primary nerve of the Parasympathetic Nervous System.  It isn’t an even mix, though, about 80% of the axons inside the vagus nerve are sending signals from the body to the brain.

The Vagus nerve consists of Five Components with distinct functions: --Brancial motor: (special visceral efferent) Supplies the voluntary muscles of the pharynx and most of the larynx, as well as one extrinsic muscle of the tongue. --Visceral motor: (general visceral efferent) Parasympathetic innervation of the smooth muscle and glands of the pharynx, larynx, and viscera of the thorax and abdomen. --Visceral sensory: (general visceral afferent) Provides visceral sensory information from the larynx, esophagus, trachea, and abdominal and thoracic viscera, as well as the stretch receptors of the aortic arch and chemoreceptors of the aortic bodies . --General sensory: (general somatic afferent) Provides general sensory information from the skin of the back of the ear and external auditory meatus, parts of the external surface of the tympanic membrane, and the pharynx. --Special sensory: (special afferent) A very minor component. Provides taste sensation from the epiglottis region.

A simplified explanation to describe "how it works"- Rather than sending signals out from brain, or bringing sensory info back to the brain, it does both, and it allows "pieces parts" or "stations" along the way to communicate with each other without directly routing through the brain.

It controls much of the movement of the mouth and let’s the esophagus "synch up" with back of tongue motions in order to make swallowing possible. And signals the lower organs of the digestive tract to adjust activity when "food is on the way!"

The Vagus nerve also sends signals to and for those "unconscious" or reflex reactions- such as swallowing when not thinking about it consciously. Often the example given is- "swallowing while sleeping so you don’t drown in saliva." It is associated with Nausea governing factors, Relaxation, (particularly pulse rate) digestion synchronization, etc.. It’s "Fence-sitting" behavior as both Voluntary and Involuntary signal provider, makes it a key factor in most Bio-Feedback processes for reducing stress levels. -http://www.bio-medical.com/product_info.cfm?inventory__imode l=STRESSERASER