Polyvagal theory (PVT) is a collection of proposed evolutionary, neuroscientific, and psychological constructs pertaining to the role of the vagus nerve in emotion regulation, social connection and fear response. PVT was introduced in 1994 by Stephen Porges. There is consensus among experts that the assumptions of the polyvagal theory are untenable. PVT is popular among some clinical practitioners and patients, but it is not endorsed by current social neuroscience.
Polyvagal theory takes its name from the vagus, a cranial nerve that forms the primary component of the parasympathetic nervous system. The traditional view of the autonomic nervous system presents a two-part system: the sympathetic nervous system, which is more activating ("fight or flight"), and the parasympathetic nervous system, which supports health, growth, and restoration ("rest and digest"). Polyvagal theory identifies a third type of nervous system response – the 'social engagement system', a hybrid state of activation and calming that plays a role in our ability to socially engage (or not).
Polyvagal theory views the parasympathetic nervous system as being split into two distinct branches: a "ventral vagal system" which supports social engagement, and a "dorsal vagal system" which supports immobilisation behaviours, both "rest and digest" and defensive immobilisation or "shutdown". Polyvagal theory was introduced by behavioral neuroscientist, Stephen W. Porges, in his presidential address to the Society of Psychophysiological Research in Atlanta, Georgia on October 8, 1994.
The talk was later published in Psychophysiology 32 (1995) with the title "Orienting in a defensive world: Mammalian modifications of our evolutionary heritage. A polyvagal theory" (Porges, 1995).
Theory
According to the theory, three organizational principles can be distinguished:
Hierarchy: The autonomic nervous system reacts in three reaction patterns, which are activated in a specific order. Neuroception: In contrast to perception, it is here a cognition without awareness, triggered by a stimulus such as danger. Co-regulation: The need to feel safe enough to allow oneself to be in relationships, which is difficult for traumatized people.
When it comes to immobilization, the decisive factor for Porges is whether immobile in safety or frozen because of the feedback of danger.
Porges describes the three neural circuits as regulators for reactive behavior. His findings about the ANS were taken into account e.g. in the modern therapy of childhood trauma and are used by trauma therapists such as Bessel van der Kolk, Peter A. Levine and Marianne Bentzen. The "autonomy" of the vegetative self-regulation refers to the fact that biologically fixed, automatically running internal processes are adapted and regulated via the VNS, which can therefore not be consciously influenced directly by humans, but at most indirectly. This forms in the course of childhood and according to the suggestions of the parents or the caregivers. If the caregivers have a grown-up, developed system, then the child can also develop its resilience. However, if the caregiver is traumatized or has other impairments, the child cannot develop a stress-resistant adult nervous system.
The polyvagal theory is not simply a "theory of relaxation techniques" like autogenic training and others. According to the polyvagal theory, it is possible to strengthen a nervous system that has not yet grown up or has been dysregulated by trauma. "Pendulum exercises" can be used for this: the principle is to intentionally bring oneself out of relaxation into light stress and then back into a safe state. By oscillating between these activation states, the nervous system will be trained and will find its way back to relaxation more quickly.
Hypothesized phylogenetic subsystems/stages
The vagus nerve is a primary component of the autonomic nervous system. The polyvagal theory focuses on the structure and function of the two efferent branches of the vagus cranial nerve, both of which originate from the medulla. More specifically, each branch is claimed to be associated with a different adaptive behavioral strategy; the ventral branches are more restful in nature and the dorsal ones are more active in nature. The vagal system is claimed to be inhibitory of primal instincts by being part of the parasympathetic nervous system, and in opposition, the sympathetic-adrenal system is involved in mobilization behaviors. According to polyvagal theory, these opposing systems are phylogenetically ordered and activated for responses.