THE PSYCHOLOGICAL NOTIONS YOU MUST KNOW ABOUT Pt. 2

The Evolution of the Autonomic Nervous System (ANS) in Mammals

During the evolutionary transition towards mammals, the organisation of the nervous system underwent a very important change. In ancient reptiles, the Autonomic Nervous System (ANS) regulated the animal's metabolism via what we call today the sympathethic and the parasympathetic branches. The ANS controlled and still controls, even in us, practically every system in our body, the cardiac, the circulatory, the respiratory, the muscular, the skeletal, the digestive, the excretory, the endocrine, the immune, and even the reproductive system! Modern reptiles continue to do so, and we, for the most part, do so too, but we, differently from reptiles, are endowed with a circuit, yet to be named, which enables us to down regulate the activity of some of our organs via interactions with other mammals (and oh hey! Incredible but logical, interactions with mammals other than humans work in the same way here).  

Until the age of reptiles the ANS was divided into two branches alone, the sympathethic and the parasympathethic branches, and these were thought to operate only in antagonism, when one was ON the other was OFF. More precisely the sympathethic circuit increased energy mobilization, providing energy for Fight-Flight responses to threat. This "move" response inhibited the parasympathethic system which worked in favour of a defense mechanism too, but did so by decreasing activity to such a low point that the reptile would fall into a state of immobilization. 

This would happen because by decreasing the heartbeat and the respiration rate, a low level of blood oxygenation would kick in, switching on a temporary paralysis of most of the body. This was a very cool trick of evolution, and one that I am sure you are very thankful for, for it saved countless reptiles and birds! 

However, in mammals, the very same mechanism caused and still causes havoc, because differently from reptiles, our bodies and brains cannot survive for more than a few minutes at low oxygen levels. Those who we hear died of fear, for instance, actually died because their parasympathetic system kicked in so hard that oxygen levels dropped too low, which is totally cool if they had been dragon mutants, but in the case of being a human it was fatal death! 

Neurologist Stephen Porges explains:

If we look at early born babies when they’re at critical risk, what they’re doing is having bradycardias – the heart rate is slowing so much that the baby is not getting enough oxygen to the brain. The vagus in the ANS is actually causing that, just as the vagus, in healthy, full-term babies and healthy adults, facilitates our oxygenation and helps us feel calm. How can the vagus do both? It really doesn’t do both – they’re just different circuits in that vagal cable, and the newer mammalian circuit of the vagus, functions in a way to protect us from the older “vagus of death”

Understanding the Polyvagal Theory and Its Significance

By decoding and really going through comparative neural anatomy and how things changed with evolution, distinguished professor Porges was able to give a proper neurological explanation of these paradoxical nervous system reactions, and coined the Polyvagal Theory.

The theory is named "polyvagal" to emphasize the fact that there are more than one vagal circuits in the vagal nerve - two non-myelinated circuits associated with the fight-flight and freeze-shutdown responses, and one myelinated circuit, related to feeling safe and promoting spontaneous social behaviour ( Porges 2011). Myelination basically means insulation, and insulation translates in higher signal speeds, so that the newer circuits have an advantage over the older ones because they are insulated, just like in electric cables. 

The important addition to our previous Triune Brain understanding here, is that not only Dr. Porges identifies specific evolutionary ancient circuits responsible for the fight-flight and freeze-shutdown responses, but also shows a newer independent faster circuit spreading towards the heart, lung, face, the larynx, and the ear.

 Through this faster myelinated connection a face–heart connection is established which provides mammals with an evolutionary new skill, the ability to communicate their visceral physiological state via facial expressions and intonation of voice (prosody), as well as express calm physiological states to promote calmness and social bonding ( Porges & Lewis, 2010). 

In other words, the face–heart connection enables mammals, and mammals alone, to communicate safety, detect whether a member of their group is ‘safe’ to approach, and calm or be soothed by other members of the social group. This is possible because nature improved its biological technology, and in particular its insulation properties and wiring. 

When the individual feels safe, two important features are expressed. First, bodily states are regulated by the older vagus circuits in an efficient manner to promote growth and restoration (e.g., visceral homeostasis). Secondly, because the face-heart system is bidirectional, as social interactions become safer and more spontaneous, the heart and the lung slows down. Thus, our physiological state, the state of our viscera, heart, and lung, are mechanisms that affect not only our present feelings, but also our social engagement behaviour.

The Social Engagement System has a control component in the cortex that regulates brainstem nuclei to control eyelid opening, facial muscles, middle ear muscles, muscles of mastication (e.g., ingestion), laryngeal and pharyngeal muscles (e.g. intonation), and head turning muscles (e.g., social gesture and orientation). Collectively, these muscles function both as determinants of engagement with the social environment, and as filters that limit social stimuli. The neural pathway involved in raising the eyelids, for instance, also tenses the stapedius muscle in the middle ear, which facilitates hearing human voice. (Porges 2010)

To give a few more example of this interaction, a low monotone voice, often used by males to frame the actions of a child or subordinate, triggers automatic vagal responses of defense while voices or music in the mid-range build resiliency in the individual because they reinforce a non ANS defense state (see music of the 60s! or ASMR videos today!). Singing, or playing wind instruments are other activities that engage the social vagal system and could play a conscious or unconscious role in mediating vagal hyperactivation. Playing social games, or acting, tends to engage the facial system and therefore the turning down of the sympathethic response, making us feel calm. 

However, a cluster of poor eye gaze, difficulties extracting human voice frequencies from background sounds, blunted facial expressions, minimal head gestures, and limited vocal prosody are symptoms of poor state regulation and are common of individuals with autism and other psychiatric disorders. Watch out for these signs! 

Wow! Makes me think right back to when I lived in Japan, and all those women who even in their older age continued to speak with a child like voice. I knew intuitively that this triggered feelings of protection and sympathy in me and most other men, and that somehow this drove their behaviour, but what I did not know, is that these individuals were unconsciously hacking the ANS systems of both themselves and others to moderate feelings of stress and produce 'safe' physiological states! Here is a vocal ASMR example of what I mean, if the theory is correct, we are likely to experience the same thing.

Neuroception: Our Unconscious Response to Environmental Cues

Now there is one final concept of the Polyvagal Theory that needs to be looked at before we explore the manner in which these theories can actually help us in our daily lives: Neuroception. Neuroception is a complex unconscious process that allows us to reflexivily respond to risk by detecting intention in the environment. 

Ok, it's a mouthful, but what this basically means is something we all can easily appreciate: it is the ability to estimate (via the viscera and other sensory information), the patterns of movement and sounds that objects and subjects in our environments are carrying out, and prepare our bodies for defense or safe interactions. For instance, we instinctively associate low frequency sounds to predators approaching and to life-threatening cues. Very high frequency sounds are cues of danger (see Porges & Lewis, 2010), and mid-tones, as the video above demonstrates, the range common to women's voices, is an indication of safety. These signals are all picked up unconsciously and reflexive programs are carried out before we may intervene.

When our nervous system is detecting a neuroception of danger, risk, or fear, we should be smart and navigate out of it as opposed to beating ourselves up and stay.

Wishing you Well,

Your Shrink in Bansko