A short talk/transcript by Dr. Arielle Schwartz introducing polyvagal theory and its implications for trauma and safety. It explains the autonomic nervous system’s background role, critiques the simple sympathetic vs. parasympathetic framing, and describes two vagal circuits (ventral/‘social engagement’ and dorsal/‘shutdown’) that underlie connection versus collapse responses, with clinical observations (e.g., NICU bradycardia) motivating the theory.
Chapters
Foreign. Succinctly. Polyvagal theory is giving us deeper insight into our autonomic nervous system. Your autonomic nervous system is the part of the nervous system that functions without you having to consciously think about it. It kind of works on your behalf, constantly in the background to help you navigate sleep, wake cycles, brief breath rate, heart rate, blood pressure, body temperature, does all of these things for you. And when I was first studying this, actually I was writing my master's thesis in the 1990s, and much of the literature at that time about the autonomic nervous system was talking about this kind of dichotic system of our sympathetic system being the fight flight system and our parasympathetic system being our rest and digest system. Right, We've all heard that. Yeah, yeah, yeah. It's a, it's a partially true story. It's a partially true story. So when we look more deeply at the parasympathetic nervous system, sometimes that takes us into rest and digest or our relaxation response, beautiful healing state. However, sometimes, and this can occur in the case of trauma, high trauma, high danger, life threat, no exit type situations. Rather than going into rest and digest, our parasympathetic nervous system has a kind of more primitive, more primal survival expression that takes us into more of a shutdown, a feigned death, an urge to get small, a kind of loss of mental capacities. We go into this very kind of deeply conserving of energy state of heart rate slows down, respiration rate slows down, and we are conserving what we need to make it through something really dangerous. It can even in some case, literally lead to a vasovagosyncope or a faint response. So the vagus nerve sits at the center of this, what we'll call parasympathetic paradox, this idea that our parasympathetic nervous system has these two expressions, resting and collapsing. And Dr. Stephen Porges, who developed the polyvagal theory, he was observing this especially with infants in the NICU in intensive care units, where when they would go into that older parasympathetic response, they were at higher risk of death. They would go into what's called bradycardia. Their heart rate would slow rapidly down. And, and so this question, because the vagus nerve is always linked to our parasympathetic response, so how could the vagus nerve and the parasympathetic nervous system have these two expressions? So that led to the development of the polyvagal theory. Polyvagal theory means poly multiple vagal vagus nerve circuits so we have multiple ways in which the vagus nerve engages to help protect us in the world. One of those circuits is what he terms the social engagement system. It's an upper circuit or a ventral vagal circuit. It's forward in the brainstem. And it's basically evolved for us as mammals to help us connect to each other in order to downregulate out of fight flight, down regulate out of our sympathetic nervous system so that we can bond, so that we can reach for connection, so that we can nurse, so that we can soften into contact with another person and basically be in proximity in order to do that. I can't be in fight flight. And if you've ever held a baby who's in fight flight, their bodies are stiff. They're not kind of melting into the holding environment of the caregiver. And that makes it so hard to soothe that baby. Yeah. Wow. Yeah. And then there's a. There's another vagal circuit, this dorsal vagal circuit that goes lower down into the body. It comes down out of the back of the. The brain stem. And that vagal circuit is associated more with the deep rest and digest state, the healing. However, when we are not safe, Right. Our social engagement system is going to help us determine, am I safe? Are there cues of safety will also help us determine is there danger, is there life threat? And if we get the cues that there's a life threat, that there's no exit. Right. Whether that's because the trauma is ongoing or whether it's a really big threatening event, it will signal that lower vagus to protect us.
