Polyvagal theory

Polyvagal theory (PVT) is a collection of proposed evolutionary, neuroscientific, and psychological constructs pertaining to the role of the vagus nerve in emotion regulation, social connection and fear response. The theory was introduced in 1994 by Stephen Porges. There is consensus among experts that the assumptions of the polyvagal theory are untenable. PVT is popular among some clinical practitioners and patients, but it is not endorsed by current social neuroscience.

Polyvagal theory takes its name from the vagus nerve, a cranial nerve that forms the primary component of the parasympathetic nervous system. The traditional view of the autonomic nervous system presents a two-part system: the sympathetic nervous system, which is more activating ("fight or flight"), and the parasympathetic nervous system, which supports health, growth, and restoration ("rest and digest"). Polyvagal theory views the parasympathetic nervous system as being split into two distinct branches: a "ventral vagal system" which supports social engagement, and a "dorsal vagal system" which supports immobilisation behaviours, both "rest and digest" and defensive immobilisation or "shutdown". This "social engagement system" is a hybrid state of activation and calming that plays a role in the ability to socially engage.