New Division of the Autonomic Nervous System
Cordell E Logan, ND
Historically the autonomic nervous system was considered to be divided into the sympathetic and the parasympathetic divisions. The sympathetic is the “fight or flight” part, whereas the parasympathetic is the calming part. See a standard text to learn more about what these do.
Dr. Stephen Porgus, now at the University of Illinois in Chicago, questioned how the autonomic nervous system (ANS) functioned in emotional and social aspects, especially as related to infant and child development. He thought there must be a close connection with this to the nervous system. We speak of having a feeling and of gut feelings. How is this explained?
After decades of research and reviews of the literature, he has proposed the Polyvagal Theory. This new division is labeled the Social Nervous System. When a baby is born, breathing and heart action are paramount. The sympathetic nervous system causes an increase in heart rate. Stress can do this, but we don’t want a new-born to be stressed on day one just to get the heart working. Yet the parasympathetic nervous system slows the heart and breathing. If there were no brake on this, the heart might become too slow, resulting in diminished breathing and lack of oxygen; not good.
So what balances this? The main part of the parasympathetic nervous system is fed via myelinated nerves from Cranial nerve X, known as the vagus nerve. This is the historical definition. However, there is another part of this nerve that is unmyelinated, having no sheath around it as does the other part. This section is more primitive. We have “fight or flight” with the sympathetic division; and the calming aspects with the parasympathetic division. There is a third: the “freeze” response. Reptiles do this to feign death as part of their survival mechanism. Humans can “freeze” as well as an emotional response. Normally this is not good. A case is related about a women who could not unfasten her seat belt in an accident because she “froze” in the seat. The freezing, feigning death, immobilization part is from the unmyelinated part of the vagus nerve. It is slow to react (no myelin to speed the nerve).
The vagal “brake” that permits the parasympathetic action to not go too far in calming, or slowing the heart or breathing, is what Dr. Porgus has called the “vagal paradox.” The neural feedback mechanism here involves sensory inputs with nerve actions. Since research has not dealt deeply into this area, Dr. Porgus labeled this idea as neuroception.
All this ties in with the central nervous system from the brain on down. It is a check and balance system. It has been learned that normal social response is elicited by the myelinated vagus. It tends to inhibit the sympathetic actions. A poor functioning, from whatever source, of this system calls in action the more primitive part of the vagus, the unmyelinated. This cascades into behavioral problems, from the infant, from childhood, into adulthood. Drugs can disrupt normal nerve development. High stress, PTSD, poor diet, even lack of exercise, all affect the body. Autism symptoms have been recognized in this model, as are hyperactivity syndromes.
Poor functioning of the autonomic nervous system may manifest with the following symptoms:
• Poor eye contact (some cultural habits may interfere with this observation).
• May be hard to hear voices from those close by in a noisy environment such as in a restaurant. This connects with the middle ear muscles.
• Voice and head movements may not be as expected in the normal.
• Social engagement may be diminished.
• There can be a decrease in respiratory sinus arrhythmia (RSA), as it is normal to see respiratory variation with the normal heart beating pattern. This often is a testing criterion for monitoring behavioral changes.
Hormones, especially oxytocin, relates with all of this. Oxytocin is produced in the hypothalamus gland and released from the posterior pituitary into the blood stream. Low oxytocin relates to health problems.
Borderline Personality Disorder (BPD) affects a large population. Job performance, home life, and school performance are all implicated. Some degree of abnormal functioning in the autonomic system is involved.
If drugs affect the nervous system, then food must also. Thus it is important to have a proper diet, along with exercise, social skill development, and even spiritual development.