Table 1.

Features of the polyvagal theory

1	Polyvagal theory focuses on the foundational survival oriented neural circuits located in the brainstem that regulate the autonomic nervous system and support homeostatic processes
2	Polyvagal theory emphasizes the hierarchical nature of the nervous system with foundational survival focused circuits functioning as a neural platform for higher brain structures involved in cognitive and emotional functions (i.e., disruption of foundational circuits compromises higher brain processes)
3	Autonomic state functions as an intervening variable biasing reactions to events and even pathogens
4	Consistent with the Jacksonian principle of dissolution (Jackson, 1884) autonomic state is regulated by three neural circuits (i.e., ventral vagus, sympathetic nervous system, dorsal vagus) that form a phylogenetically and maturationally ordered hierarchy in which newer circuits inhibit older circuits
5	Within the vagus nerve there are two neuroanatomically distinct vagal efferent pathways that originate in different areas of the brainstem (ventral, dorsal)
6	The dorsal vagus originates in the dorsal nucleus of the vagus and has unmyelinated vagal motor fibers that primarily regulate organs below the diaphragm (e.g., gut). The dorsal vagus has unmyelinated cardioinhibitory pathways that appear in most situations to be dormant but may become activated in life threat situations (e.g., hypoxia)
7	The ventral nucleus of the vagus (i.e., nucleus ambiguus) is the source of myelinated cardioinhibitory pathways projecting to the heart in mammals
8	The ventral vagal cardioinhibitory pathways have a respiratory rhythm that is observed as RSA with the amplitude of RSA reflecting the chronic cardioinhibitory influence of the vagus (i.e., cardiac vagal tone) on the heart
9	Neuroanatomically the special visceral efferent pathways within cranial nerves V, VII, IX, X, and XI with the ventral vagus form an integrated social engagement system that regulates the neural structures involved in ingestion at birth and social communication throughout the lifespan
10	The social engagement system by recruiting the calming circuits associated with the ventral vagus enable social interactions (i.e., co-regulation) to constrain the defensive circuits involved in fight/flight and shutdown (e.g., death feigning) to support play and intimacy
11	Through the process of neuroception (i.e., the nervous system’s detection of signals of risk without awareness) signals of threat reflexively shift autonomic state to optimize survival through mobilization and immobilization strategies, while signals of safety calm autonomic state and support the homeostatic processes of health, growth, and restoration
12	Feelings of safety reflect an autonomic state supporting homeostatic processes and form the foundational neural platform for sociality