The polyvagal theory, born from the research and writings of Stephen Porges, Ph.D., is a new understanding of the autonomic nervous system (ANS). His groundbreaking work provides an elaborate mapping of the psychophysiological systems that govern the traumatic state and illuminate the pathways for recovery and integration from these deleterious states of mind and body. Prior to the polyvagal theory, we had been taught that the ANS was organized by a paired antagonism between the sympathetic and the parasympathetic nervous systems, which functionally competed by either increasing or decreasing activity of neurophysiological states. Porges proposes:
Phylogenetically, a hierarchical regulatory stress-response system emerged in mammals that not only relies on the well-known sympathetic-adrenal activating system and the parasympathetic inhibitory vagal system, but that these systems are modified by myelinated vagus and the cranial nerves that regulate facial expression which constitute the social engagement system. Thus, phylogenetically, self-regulatory development starts with a primitive behavioral inhibition system, progresses by the evolution of a fight-flight system, and, in humans (and other primates), culminates in a complex social engagement system mediated by facial gestures and vocalizations.3
The most primitive of these regulatory systems is over 500 million years old stemming from its origin in early jawless fish species. Its primary function is immobilization, metabolic conservation, and shutdown. This is the unmyelinated dorsal vagus, and its target of action is the viscera. Next in development is the sympathetic nervous system (300 million years ago), mobilizing the organism by activating the adrenals providing fight or flight by way of the limbs, as witnessed in amphibians, frogs, sailfish, etc. The last-developing system (90 million years ago) exists only in mammals, with its greatest refinement in primates, mediating complex social and attachment behaviors. This system is neuroanatomically referred to as the “smart vagus” and is linked to the cranial nerves regulating the muscles of the face, throat, middle ear, heart, and lungs. It is the myelinated ventral vagus and is associated with emotional intelligence.
Our nervous systems are continuously evaluating potential risks in the environment – a non-conscious detection system termed neuroception by Porges. The detection of a person or circumstance as being safe, dangerous, or life-threatening triggers neurobiologically determined prosocial or defensive behaviors. In essence, Porges has defined two defense systems, fight/flight or freeze – a great contribution to all of the social sciences but particularly of importance for somatically based therapies such as Rolfing® SI. Practitioners of bodily-based therapies witness states of hyperarousal (sympathetic nervous system) and hypoarousal (dorsal vagal parasympathetic nervous system) in their clients everyday. Here’s a general schema of the two:
Psyche’s way of saying: “This a lot . . . I must hold on!”
Dorsal vagal parasympathetic NS
Immobility – frozen
Numbness – ‘waxy flexibility’
Escape when ‘no escape’
Psyche’s way of saying: “This is too much . . . I give up!”
There are many factors determining whether a person will go into hyper- or hypoarousal. Obviously, the intensity of the stress (i.e., is it dangerous or life-threatening) is one element; but perhaps most critical is the person’s ‘window of tolerance.’ Dr. Daniel Siegel proposes that between the extremes of sympathetic hyperarousal and parasympathetic hypoarousal is a ‘window’ or range of optimal arousal states in which emotions can be experienced as tolerable and experience can be integrated. Exposure to threat or trauma challenges one’s window of tolerance with ANS-activated states accompanying animal defense survival responses such as fight, flight, or freeze (submission). Once the threat has passed, many victims stay in their hyper- and hypoaroused defensive states. Thus, traumatic experiences result in an array of cognitive, emotional, and physical symptoms: fear, shame, rage, terror; numbing of feelings and body sensations, overactivity of the stress response, and painful and negative beliefs about oneself. With a dysregulated nervous system that can’t modulate heightened emotional states or states of depression and numbness, a person reports an inability to tolerate arousal without being overwhelmed. Somatic responses become frozen, collapsed, or driven and action becomes impulsive or impossible.