User:Jtwsaddress42/Quotes/Porges, Stephen 1997a

The Social Engagement System: Phylogenetic Origins of Behavioral and Autonomic Components "'The Phylogenetic origin of the behaviors associated with the social engagement system is intertwined with the phylogeny of the autonomic nervous system. As the striated muscles, via special visceral efferent pathways, evolved into a behavioral system that regulated social engagement behaviors, there was a profound shift in neural regulation of the autonomic nervous system. Phylogenetically, these changes in both somatomotor and visceromotor regulation are observed in the transition from reptiles to mammals. As the muscles of the face and head evolved into an ingestion (i.e., nursing) and social engagement system, a new component of the autonomic nervous system (i.e., a myelinated vagus) evolved that was regulated by a brainstem nucleus, which was also involved in the regulation of the striated muscles of the face and head (i.e. nucleus ambiguus). This convergence of neural mechanisms resulted in an integrated social engagement system with a synergism between behavioral and visceral features of social engagement. Thus, activation of the somatomotor components would trigger visceral changes that would support social engagement, while modulation of visceral state would either promote or impede social engagement behaviors... Moreover, activation of the social engagement system dampens the neural circuits including the limbic structures that support fight, flight, or freeze behaviors.'

Stephen Porges (1997)"