I realized that there was a thrilling undiscovered country to be explored in the mechanisms of the mammalian nervous system.
—WILDER PENFIELD
The ability to respond to and recover from the challenges of daily living is a marker of well-being and depends on the actions of the autonomic nervous system. When you think about the autonomic nervous system, where do your thoughts go? Perhaps you have a fuzzy memory of biology learned long ago and a feeling that this system is somehow important to survival. With the development of Polyvagal Theory, Stephen Porges has provided a modern map of the territory of the autonomic nervous system and a new understanding of the ways it shapes moment-to-moment experiences of connection and protection.
The three organizing principles of Polyvagal Theory are:
1. Autonomic hierarchy
The autonomic nervous system is divided into three parts, each with its own set of protective actions.
•The earliest dorsal vagal system brings strategies of immobilization.
•The sympathetic system, next to arrive, adds fight and flight.
•The most recent ventral vagal system offers the ability for safety through connection and social engagement.
•Recognizing where on the hierarchy your client’s autonomic nervous system has taken them is fundamental to the success of therapy. When the autonomic nervous system has moved into a dysregulated dorsal vagal or sympathetic state, your client’s body and brain have been hijacked and they are held in a survival response. When the ventral vagal state is active, body and brain work together, and processing and change are possible.
2. Neuroception
Neuroception, detection without awareness, describes the way the autonomic nervous system interfaces with the world.
•Working below the level of awareness, the autonomic nervous system listens inside the body, outside in the environment, and in the relationships between people.
•Reshaping the autonomic nervous system involves first making the implicit experience explicit by bringing perception to neuroception and then adding context through the lens of discernment.
•Neuroception is at work in every moment of the therapy session. The ability to tune into the implicit autonomic conversations that are happening between you and your clients is an essential part of creating therapeutic presence and building trust in the therapy process.
3. Co-regulation
Co-regulation is a biological imperative. It is essential to survival.
•The ability to self-regulate is built on ongoing experiences of co-regulation. Through co-regulation we connect with others and create a shared sense of safety.
•With a reliable, regulating other, we engage in the rhythm of reciprocity and build experiences of safety in connection. For many of your clients this earliest experience of being with a safe person in a safe place is missing.
•As a therapist, you are responsible for being a regulated and regulating presence for your clients. Without your predictable, ongoing offer of co-regulation in the therapy session, your clients will struggle to engage in the therapeutic process of change.
Over the course of evolution both the brain and the autonomic nervous system have grown and changed. John Hughlings Jackson proposed a hierarchy of brain structures in which higher levels regulate the function of lower levels; he defined dissolution as a sort of evolution in reverse that happens when higher brain structures no longer inhibit lower structures (Franz & Gillett, 2011; York III & Steinberg, 2011). You see this when your client’s prefrontal cortex shuts down in response to a situation that feels overwhelming, leaving their limbic system to mount a response. The autonomic nervous system can likewise be seen through the lens of hierarchy and dissolution. Looking at the evolution of the autonomic nervous system, there is an emergence of a three-part system that is distinct and measurable, creating a predictable hierarchy of response (Porges & Carter, 2017). The autonomic nervous system also follows a predictable pathway of dissolution, moving from ventral vagal safety and connection down the hierarchy into the sympathetic mobilization of fight and flight and finally to the earliest state of dorsal vagal shutdown.
Using images, you can feel the flavor of each autonomic state. Humans evolved from ancient reptiles similar to turtles (Porges, 2015a). The image of the turtle hiding in its shell is an apt one for the dorsal vagal state of disconnection. Continuing to the sympathetic nervous system, imagine the darting movements of a fish reacting in an instant to avoid a predator. Finally, arriving in the uniquely mammalian ventral vagal state, picture people talking and smiling in a shared moment of connection.
Darwin understood that the brain and the heart were connected and engaged in a two-way conversation through what was then known as the pneumogastric nerve, now called the vagus or Cranial Nerve X (Darwin, 1873). William James (1890) wrote that, “A purely disembodied human emotion is a nonentity” (p. 194) and that intellectual feeling must be connected to “a bodily reverberation of some kind” (p. 201). This early understanding of the two-way conversations between the body and brain was abandoned in favor of envisioning the brain as the dominant force directing daily experience. Polyvagal Theory reestablished the understanding that through bidirectional pathways, psychological processes influence body state and body state colors your perceptions (Porges, 2009). Sensory fibers send information to the brain and motor fibers bring information back, initiating a response. Corticobulbar (cortico for cortex and bulbar for a region of the medulla) pathways connect the brain’s motor cortex to the autonomic nervous system via the vagus, giving the cortex a way to exert some control over brainstem responses (Porges, 2011).
Until recently, scientists had no way to understand this brain-heart connection except through using animal models to test hypotheses and postmortem study of body systems. Researchers are now able to study the autonomic nervous system and patterns of brain activity in living humans in real time. Through the use of EEGs, biofeedback, and wearable devices, we can listen in on the conversations that travel the pathways between the autonomic nervous system and limbic and cortical networks. Heart rate variability, the naturally occurring changes in the beat-to-beat rhythm of the heart, is indicative of the state of the autonomic nervous system and might be a biomarker of general stress and health (Evans et al., 2013). High and low variability is associated with changes in the ability for the brain (prefrontal region) to promote cognitive and emotional self-regulation (Park & Thayer, 2014). Another rhythm, respiratory sinus arrhythmia, tracks the changes in heart rate associated with breath patterns (Sahar, Shalev, & Porges, 2001). This beat-and-breath rhythm shifts in response to both physical and psychological needs. In clinical work, you sense body-brain communication in how deeply your clients respond to an experience, how long their response lasts, and how often it occurs. You see your clients’ body-brain conversations in action. As technology advances, you may soon be able to see changes in autonomic state as a session unfolds through numbers tracking moment-to-moment shifts and changing colors that illustrate the autonomic experience. It is interesting to consider what a dual lens of observing your client’s body and behaviors in combination with the next generation of physiological measurement tools might bring to the clinical interaction.
The autonomic nervous system shapes the way you experience your life. Beliefs, behaviors, and body responses are embedded in the autonomic hierarchy. Physiology and psychology are interconnected. State and story work together in a persistent and, if not interrupted, enduring loop. Polyvagal Theory invites you into the science of feeling safe enough to fall in love with life and take the risks of living. By bringing explicit awareness to the implicit workings of the autonomic nervous system you can learn to become a regulated and regulating resource for your own well-being and for the people around you. In the next chapters we’ll look beneath the behaviors and beliefs and begin to answer the question of how physiology can create the conditions that support safety and connection.