Sign up below to receive Dr. Nathan’s newsletter
A New Understanding of the Autonomic Nervous System
What we are going to talk about today is an exciting new understanding of the autonomic nervous system. First, let us begin our discussion by getting a good handle on the name. Poly is the root word for “many” or “multiple” and vagal refers to the vagus nerve, our tenth (X) cranial nerve. A major component of this concept is new research which shows that the vagus nerve, a long and important nerve that goes from the brain to many of our most important organs including the heart, lungs, and intestines (all the way to the descending colon) is actually made up of two separate nerves. These nerves fuse to become the vagus nerve, but come from two completely separate areas of the brain. We are just beginning to understand that these two parts of the vagus nerve, anatomically called the dorsal and ventral branch, subserve different functions.
Until recently, the autonomic system has been clearly divided into two well described branches: the sympathetic and parasympathetic systems. Most of you are well aware that the sympathetic system is referred to as the “fight or flight” system, activated by stress. The parasympathetic system is considered to balance the effects of stress by relaxing the systems that have been activated by stress. These are primitive responses, following patterns that were etched into our nervous system as we evolved into human beings.
When threatened with a dinosaur (or tax audit), our eyes dilate, bronchial tubes dilate, pulse goes up, muscles become more reactive—-all to enable us to either fight the dinosaur or run. When translated into more modern stressors, like a tax audit, or a divorce, or being late for work, those same physiological reflexes kick in, but are much less helpful or adaptive for what we are now trying to cope with.
For decades, this is how we understood this part of our nervous system, and often it seemed somewhat out of our control. As modern times became more and more stressful, activation of the sympathetic system contributed significantly to the cause of many illnesses. Many medical writers urged patients to counterbalance these effects by using breathing and relaxation techniques to stimulate the parasympathetic system.
Dr. Stephen Porges, in 1992, after years of studying the autonomic responses in his laboratory, proposed the Polyvagal Theory, when he realized that there was another component to this system that had not been recognized. He described the sympathetic response as coming from the dorsal branch of the vagus nerve, but newer anatomic and physiological studies showed that there was a separate ventral branch of the vagus nerve which had the capacity to override both the sympathetic and parasympathetic responses, hence, had the ability to control those. Dr. Porges recognized that there was another stress response which humans utilized when the “fight or flight” response was not working, and that was
to “freeze” or become immobilized as a strategy for dealing with overwhelming stress. The most obvious way to visualize this is by watching a possum go limp, “playing dead” until what is threatening it decides to go away when no response is detected. Humans do this as well, and if you reflect on the responses you have seen to overwhelming stress, you will probably recognize times when you, or those near to you, have become paralyzed by that stress. Dr. Porges recognizes that this commonly occurs when individuals are faced with physical abuse or attacks in wartime, and those who have had to deal with this are often left with a PTSD-type of response.
The underlying dynamic of this response is that these individuals no longer feel SAFE.
It turns out that the major function of the ventral branch of the vagus nerve is to discern safety and it is understanding the importance of safety that is the primary focus of polyvagal theory. The perception of safety is hard-wired into our nervous system. If our nervous system does not perceive us to be safe, no amount of rationalization will change that physiological response. This is another “systems” way of understanding the Cell Danger Response (CDR). We’ve discussed the CDR in previous newsletters, and Dr. Naviaux’s model of how mitochondria respond to a threat dovetails closely with the polyvagal theory. Both models emphasize that the body will continue to operate as if it is under threat until it is convinced that it is safe.
This applies to a wide variety of chronic illnesses: CFS/ME, fibromyalgia,
Lyme disease, mold toxicity, and autism are examples of conditions that are difficult to heal because the patient has been under duress for so long that is hard to be sure that they are truly on the road to healing and will once again be safe. Most of these illnesses demonstrate autonomic dysfunction to greater or lesser degrees, and therefore finding a way to help that patient feel safe must be an integral part of the treatment process.
It turns out that vagal nerve function is intimately connected to several other cranial nerve functions, especially cranial nerves V (trigeminal), VII (facial), IX (glossopharyngeal) and XI (spinal accessory). Taken from an evolutionary perspective, Dr. Porges recognized that all of these, among other functions, control the movements of the face, neck and shoulders.
He has made the fascinating observation that how the upper part of the face moves (around the eyes and cheeks) plays a profound role in how we read the safety and accessibility of those around us. The phrase “his smile did not reach his eyes” is an excellent example of this: we recognize either intuitively or by careful observation, that some people make an effort to smile, but there is no motion of their upper face or eyes, and we have learned not to trust that. This would be similar to the immobilizing effects of botox. The expressiveness of our face, therefore, informs others about what we are really feeling and others will respond to this accordingly. These muscles around the eyes are regulated by the facial (VII) cranial nerve, and so is a tiny muscle in the ear, called the stapedius, which regulates our perception of sound. Dr. Porges writes “when the middle ear muscles aren’t contracting appropriately, we are bombarded by low frequency rumble from background noise. This compromises our ability to understanding human voices” and we tend to withdraw from others.
A genuine smile “lights up our eyes”, and a forced one does not. Even if we are not consciously aware of what we are seeing in the faces of others, our primitive nervous system is hard-wired to perceive this and respond to it.
Therefore, by observing and testing these muscles, we get information about how functional the cranial nerves are that control those muscles. A simple way of examining this is to ask the patient to say “ah, ah, ah, ah, ah” while shining a light into his throat. If the movement of the uvula is minimal or off to one side, this is a clear demonstration of a dysfunctional vagus nerve. Another test is to ask the patient to gag, gently…..if they cannot easily do so, again the vagus nerve is likely to be dysfunctional.
Dr. Porges uses this information to emphasize how important it is to create an environment in your treatment room that encourages the perception of safety. This includes the color of the walls, lighting, and the tone and timbre of your voice. All of these will be recognized by the patient as either safe, or not, and they will respond accordingly. This is most glaringly obvious in hospital settings, where constant noises and sounds are antithetical to this perception, and patients often feel unsafe in their scanty gowns, examined and tested constantly (for “vital signs”), with little sense of dignity or involvement in the decision making process.
Understanding the vital importance of the perception of safety and its role in healing the autonomic nervous system actually allows us to approach treatment with a variety of more precise and specific efforts.
I would like to recommend a book by Stanley Rosenberg called
“Accessing the Healing Power of the Vagal Nerves.” It provides an excellent overview of Dr. Porges’ theory, and equally important in Part II, gives a series of simple, easy-to-do exercises that specifically quiet the ventral branch of the vagus nerve and the associated other cranial nerves. It takes only 5-10 minutes a day, and my patients are already reporting benefits by doing this daily. Rosenberg utilizes craniosacral manipulation to accompany his exercises, which is a wonderful combination. If you are looking for a cranial practitioner, I would suggest you look for one trained in Biodynamic Osteopathy, and if you go www.jamesjealous.com
The use of FSM (Frequency Specific Microcurrent) allows us to quiet the vagal nerve as well using a very gentle electrical stimulation and has proven very helpful in treatment.
I would also recommend Stephen Porges’ book “The Pocket Guide to The Polyvagal Theory: The Transformative Power of Feeling Safe,” to expand on my comments here and help you to understand this important concept in more detail.
Hopefully I have gotten you interested in this and I suspect you will be hearing a lot more about it from many sources.