Abstract: By investigating the evolution of autonomic nervous system, Porges proposed Polyvagal Theory, considering myelinated vagal nerve and unmyelinated vagal nerve have different functions. During evolution, neurological relation gradually comes into being between myelinated vagal nerve which regulates visceral state such as heart state, and the other cranial nerves which regulate the muscles of face and head, and it forms the neural substrate of emotion and social behavior. Existing empirical evidence suggests that myelinated vagal nerve is closely related to individual’s emotion expressiveness and regulation, social behavior and difficulties in emotion and social behavior. Both lower vagal tone and lower vagal suppression are related to lower ability of emotion regulation. Children with higher vagal suppression display less behavior problems and exhibit better social skill. Individuals with anxiety disorder show lower baseline of vagal tone and lower vagal suppression. Polyvagal Theory and related empirical evidence is of great significance for promoting the study of neural basis of emotion and social behavior.

Key words: emotion, social behavior, vagal nerve, polyvagal theory