Polyvagal Theory claims that the nervous system employs a hierarchy of strategies to both regulate itself and to keep us safe in the face of danger. In fact, it's all about staying safe.
Our "highest" level strategy is a mechanism Porges calls social engagement. It is a phenomenal system - connecting the social muscles of the face (eyes, mouth and middle ear) with the heart. You knew that your heart came alive with social interaction, and it's true! This system is regulated through a myelinated branch of the vagus nerve. In evolutionary terms, this is our most evolved strategy (mammals only) for keeping ourselves safe. We use this all the time to clear up misunderstandings, get help, plead for forgiveness, and so on.
The next mechanism, or strategy, is fight or flight. It's regulated by the sympathetic nervous system. This system is our fall-back strategy when social engagement isn't a good fit. (Think of seeing someone sneaking up on you!) Note that freeze is not a part of fight or flight.
Our freeze option is primal and is a remnant of our reptilian past. Freeze is a great strategy for turtles and lizards, but it's usually a bad idea for humans - think of fainting. Therefore, we typically use it last, when social engagement and fight/flight aren't going to work for us. But there are good uses for freeze. During severe injury, it shuts us down and turns off our registration of pain. We also make use of it during sex, and it helps women regulate pain and response to pain during labor.
Now these systems appear to work in tandem. The social engagement system puts the brakes on the other (fight, flight, freeze) strategies, thus keeping our heart and body active while we work through a situation. The social engagement system will release the brakes to engage a different response to the environment (i.e. running) if engagement doesn't help to get us into a safe situation.
What Can Go Wrong
We want our nervous system to operate using the social exchange most of the time. It is our most evolved way of being. It is restful and healthy because it allows our gut and other organs to do their job uninterrupted.
However, some of us are programmed from an early age to work from a fight/flight mode. Think of people who are sensory sensitive and recoil from sound, touch, smell or taste. Think of people with autism (in this case, the face to heart connection is not working). Think of people with borderline personality, depression and perhaps other disorders, too. When we are not able to work from our social engagement strategy, then we revert to a modified fight/flight strategy, which puts us in high alert. If we use too much of the fight/flight or freeze strategies, we may end up with gut issues because the gut comes to a halt and we stop digesting food during fight/flight activation.
The Polyvagal Theory has gained great acceptance over the years as pieces of it are shown to hold under laboratory findings. From a psychological viewpoint, it provides us with a rich understanding of self-regulation in the body. From a sensory processing viewpoint, it informs our understanding of sensory modulation.
If you are unfamiliar with the topic, check out the many articles on Dr.Porges' website. The most comprehensive article is The Polyvagal Perspective, and it is published here on the NIH Public Access site. It contains the physiological underpinnings of the theory as well as perspectives on development, emotions, trauma and many other topics. There is a short video of it here.
Two researchers looked at a biological marker of the social exchange system, RSA, in typical children and in children with sensory modulation issues. RSA is the measure of high-frequency fluctuation in the heart between heart beats. It is a window into the social exchange system. The researchers found that children with sensory modulation issues have a lower level of RSA than their peers, meaning that these children are better prepared to put the breaks on social strategies and instead use fight-or-flight strategies.
As part of the study, the children were (each in turn) given a sensory challenge. The chairs they were seated on tilted backwards unexpectedly. The level of RSA was monitored in each child throughout the incident. The RSA of typical children dropped quickly and then stayed low for a short time. The children with poor sensory modulation skills had a very brief drop of RSA and a quick rebound to their RSA baseline.
This implies that children with sensory modulation symptoms use different strategies to handle safety-related situations than their peers. At this time, it is harder to draw greater conclusions since we do not have an easy-access window into the fight/flight system or the freeze system. With time, we'll get a better understanding of this. The article can be found here.
Perhaps the most interesting new work making use of the Polyvagal Theory is the work of A. D. (Bud) Craig. Mapping our emotions, this is what he found. (Read about it here.)
Emotions arise from feelings in our organs and gut. The feelings are sent via the vagus nerve to the Anterior Insular Cortex (AIC) in the brain. (There's a lot going on in the vagus nerve - think of it as a cable with lots of separate wires.) The AIC captures feelings over time and stores them as snapshots of feelings. This is our working emotional memory. These feelings are massaged and integrated with the social exchange to give us both an emotional response to the world around us as well as a safety-driven strategy.
Think of this: I am relaxing in a lounge chair on the beach. I feel safe. Suddenly, a beach ball hits me. My fight or flight instinct kicks in and the sympathetic nervous system stops everything that's happening (i.e. digestion) in my organs and gut. The gut passes the feeling of stoppage as "alarm" to the brain. This translates in the brain to fear and my body is set in motion. I quickly turn and see it's a ball and that a child is nearby and smiling at me. My social engagement strategy puts the breaks on my fight/flight response and also calms my heart. I smile at the child. This sends a sense of relief to my gut and it in turn sends a "warm" feeling to the AIC. My heart is still pounding from the surprise, but my response is guided by compassion.
In the above scenario, we specifically looked at a situation with a challenge to safety. But in fact, we spend much of our time worrying about safety. Unless I am completely safe, listening to quiet music in a locked room, I will most likely have safety challenges to respond to. The challenge may be from the scary book I am reading, or from the sense of anxiety I feel when I drop a spoon on the floor. Almost any activity will involve the combined interaction of the various strategies. The bottom line: we are constantly adjusting ourselves to meet the world. Polyvagal Theory gives us a look at how this works.
This is pretty complex stuff - and the theory is still in flux. It changes with each new study that looks at the implications of Polyvagal Theory on our response to the world. It is going to impact research greatly in the years ahead. As I mentioned at the beginning, Polyvagal Theory adds a new dimension to how we see autism, sensory issues and other disorders and will, I think, inform our interventions for those disorders in a big way.
- Porges, S. W. (2008, February). The Polyvagal Perspective. NIH Public Access, PMC1868418
- Schaaf, R. C., Benevides, T., Blanche, E. I., Brett-Green, B. A., Burke, J. P., Cohn, E.S., Koomar, J., Lane, S. J., Miller, L. J., May-Benson, T.A., Parham, D., Reynolds, S., Schoen, S. A. Parasympathetic Functions in children with sensory processing disorder. Front Integr Neurosci. 2010; 4: 4. Published online 2010 March 9. doi: 10.3389/fnint.2010.00004
- Craig, A. D. (2009). Emotional moments across time: A possible neural basis for time perception in the anterior insula. Philosophical Transactions of the Royal Society of London. 364,1933-1942.