WHAT IS YOUR AUTONOMIC NERVOUS SYSTEM?
Your Nervous System is the electrical communications network of your body: the coordinating infrastructure between interior and exterior. When most people think about the nervous system they envision the brain and spinal cord (Central Nervous System, or CNS). The CNS, broadly summarized, translates inputs from outside the body (think of the extero-senses: sights, sounds, smells, tastes, touch) into information that informs you. People also think perhaps about the nerves that connect to muscles throughout the body and undergird somatic movement (Somatic Nervous System). To type on this keyboard as I am writing requires the refined coordination of motor movements of my fingers, hands, and arms. To do anything physical: to walk, sit, stand, wave at someone, play tennis– all of these activities require complex motor movements: the province of the Somatic Nervous System.
Yet what we have not addressed in the systems above is the way that the body talks to itself neurally (the intero-senses). The inputs that it receives from inside itself, and how it makes meaning of those. And this is the province of the Autonomic Nervous System (ANS). The fact that you know when you are hungry, thirsty, hot, or cold is a direct result of the ANS. Your ability to feel where your body is in space (proprioception) is a direct result of the ANS. Having a gut feeling, an intuition, or sensing danger is a direct result of the ANS. The ANS monitors and regulates your internal bodily processes: heartrate, bloodflow, breathing, digestion, immune function, etc., so that you don't have to consciously monitor them. For this reason, people can think of the Autonomic Nervous System as the Automatic Nervous System.
The ANS is, in fact, the neural architecture of the mindbody connection. And it has a further profound function that most humans do not understand at all. It is constantly assembling the felt information from the interior of your body into meaning. And based on this sensing and meaning-making, it tunes and re-tunes your bodily systems– imagine someone adjusting the tension on violin strings, or modulating the slides on a graphic equalizer– based on whether or not you feel safe, in danger, or under lifethreat.
The brilliance of biology is the conservation of energy. Our bodies are the most beautiful earthships imaginable, designed in the benevolent image of Nature herself to waste nothing.
When we feel safe enough to activate our Connection Systems, the primary Autonomic Systems of relating (the ancestral baseline from which we are designed to function), our ANS up-regulates our social circuitry. It flows energy into the face and voice, opens the heart, synchronizes central pattern generators in the spine, flows energy across the ventral surfaces of the hands and feet, and organizes metabolic rhythms for health and restoration. We release vasopressin and oxytocin: the love chemistry of affiliation and bonding.
Safety is a pulse and the Connection states are salugenic: they give birth to wellbeing in us and those around us. These are the states we want to learn to reside in: can in fact train ourselves to reside in.
When we feel in danger biological priority shifts to addressing threat and our systems re-tune. Activation chemistry (adrenaline and cortisol) floods our systems. Our heartrates rise, our breathing quickens, metabolism accelerates. In the absence of the coordinating impulses of safety our hearts stop conducting our bodies and brains. Our faces lose their expressivity: our ears re-tune from the melodics of the human voice to the frequencies of predators so that we can avoid being eaten. Our digestion, immune function, and memory function all down-regulate. When we are trying to get away from a bear these functions are not necessary, and in its brilliance our systems turn them down or off. In these states with the pulse of safety absent and the heart no longer coordinating rhythmicity of our internal systems their oscillatory coherence breaks down and de-coordinates. We experience this as stress of varying amplitudes.
When we feel in lifethreat, a different autonomic system takes over and our systems immobilize and collapse. We are flooded with endogenous opioids (if the bear eats us we don't want to feel it). These physiological cascades render our boundaries porous and we are ejected from our bodies: entering a continuum of dissociation. If there is activation chemistry strongly present our bodies grow rigid and immoblized and we freeze like a deer in headlights. If there is simply shutdown chemistry present we will pass out.
These shifts have been happening throughout our entire evolutionary history. Since humans became human we have grappled with this dynamic landscape and the meaning-making territory required to make sense of the physiological shifts represented by these territories.
The primary conduit of the ANS is the Vagus. Vagus, in Latin, means Wanderer. And the nerve is called thus because it meanders through the body, flowing vaguely south, in the direction of the feet, but looping back on itself like the laziest river, innervating in its passage all of the internal organs. It must do this because its purpose is to transfer information from them to relay stations throughout it (ganglia, plexuses, central pattern generators), to exchange information between organ systems, and to exchange information with the brain.
Like all nerves, though the name of the nerve changes at junctions, the Vagus flows from the deepest parts of us all the way to the periphery. It is a tree that branches from a trunk into immense arterial conduits, finer and finer ramifications, and eventually into the leaves that are the receptors in contact with tissue from which it is receiving inputs.
The immense breakthrough of Polyvagal Theory is the identification of an evolutionarily stratified Vagus (subtends different bodily systems, with different brainstem connectivity, with different myelination) that functions differentially and is governed differently depending on whether we feel safe, in danger, or under lifethreat.
The reason that this is of extraordinary import to all humans is that understanding the map of the Vagus, understanding the living texture of the way that the Autonomic Nervous System retunes across the thresholds of danger and lifethreat, the way it opens across the threshold of safety, provides us a deep geologic map of the physiological strata at the root of most illbeing (60-80% of what brings people into primary care is stress-related) and what is required to create wellbeing.
The significance of Polyvagal Theory lies not merely in its conceptualization, but the degree to which this can be harnessed clinically and culturally to transform wellbeing outcomes for humans and encourage planetary flourishing at a time when most modern people have devolved into spending most of their lives living in defensive responses.