Dana, Deb, and Stephen W. Porges. _Polyvagal Exercises for Safety and Connection: 50 Client-Centered Practices_. First edition. New York: W.W. Norton & Company, 2020. These are the 3 pathways of our autonomic nervous system: ![[pathways of autonomic nervous system.png]] This is how they evolved: ![[evolution of autonomic nervous system.png]] ## Vagus nerve system The hierarchical structure of our autonomic nervous system is the 1st organizing principle of Polyvagal Theory. The vagus nerve is not a single nerve. It is a family of nerves that wander througout the body. "Vagus" means "wanderer" in Latin. It begins in the brainstem. The dorsal vagus is the older reptilian system, and it influences organs below the diaphragm. The ventral vagus is the newest mammalian system, and it affects organs above the diaphragm. In infants, the dorsal vagal and sympathetic systems emerge first, and the ventral vagus myelinates last during the last trimester of preganancy and over the first year of life. Vagal tone is the activity of the ventral vagus, and it can be measured through heart rate variability. Heart rate variability measures the variation in time between heartbeats. A high level of variability indicates the ventral vagus is active and results in a flexible autonomic nervous system. The sympathetic and dorsal vagal nerves active an either/or experience of the world, constricting the ability to see options. The ventral vagal nerve brings about a both/and experience of the world, opening up possibilities. Five cranial nerves form the social engagement system: trigeminal, facial, glossopharyngeal, accessory, and vagal. The ventral vagal pathway from the heart connects to these nerves, forming a face-heart connection. When the ventral vagal system is overwhelmed, the next system in the hierarchy is activated – the sympathetic nervous system. This is the fight or flight response, driven by adrenaline and cortisol. Whereas the ventral vagal system is aiming for connection, this system aims for survival. When mobilization doesn't bring relief, the last system is activated – the dorsal vagal. This takes the entire system offline and into conservation mode. The effects are numbing, disconnection, and dissociation. From here, it is hard to get back to connection. To move out of collapse, we first have to mobilize through the sympathetic nervous system. If not well-regulated, this can be overwhelming, and the system can head back towards collapse. Resilience in this context is the ability to return to regulation. The sinoatrial node is the heart's pacemaker. It can slow down or speed up the heart. The ventral vagus nerve connects to this pacemaker, and this pathway is called the vagal brake. A well-functioning vagal brake allows us to engage and disengage, energize and calm, and make transitions easily. ## Neuroception This is the 2nd organizing principle of Polyvagal Theory. Neuroception is our internal surveillance system. It is the ability of our autonomic nervous system to listen to what is happening in our internal organs; scan the environment outside; and sense the connections between nervous systems. It creates cues of safety and danger. Here are some examples of information that neuroception takes in: - a pang of hunger - the size and temperature of a room - the feel of a chair - a face with a smile or forwn Neuroception is a passive radar that is tuned and calibrated through individual experiences. We build up habitual patterns of connection or protection based on our past. If we are formed by an environment that is unpredictable and full of danger, then our neuroception is biased towards protection. Conversely, if we are formed by an environment that is overly safe, then we might miss out on cues for danger. Correcting these mismatches is important to build resilience. Neuroception is an either/or switch. Safety and danger are exclusive states. We are primed for either connection or protection. A sense of safety requires both the absence of cues for danger AND the presence of cues for safety. Neuroception triggers a cascade of reactions that flows in this direction: Neuroception --> Perception --> State --> Feelings --> Behavior --> Story The stories we tell ourselves are just post-hoc rationalizations of the initial neuroceptive response. To change our habitual responses, we need to look beneath our stories and bring attention to our neuroception. ## Co-regulation