What the ANS does

To briefly review, the autonomic nervous system operates two branches: the sympathetic and the parasympathetic. The sympathetic branch mobilizes a defense against danger through the fight-or- flight response while the parasympathetic branch has typically been viewed as a system that helps to lower defenses and regain a state of calm. Polyvagal Theory offers an updated understanding of the ANS showing that the parasympathetic branch in fact has two divisions of its own, one with the potential to create social engagement and connection, and the other that activates collapse and dis- connection. These three pathways operate in a predictable hierarchy of response: ventral vagal – connection, sympathetic – fight and flight, dorsal vagal – disconnection. There is a default preference to be in ventral vagal safety and connection. When events in daily life bring too great a challenge for the capacity of the autonomic nervous system, the autonomic state shifts downward into sympathetic fight and flight and, if that does not resolve the challenge, the final move to the bottom of the hierarchy into dorsal vagal collapse and disconnection takes place.