THE HEART OF IT

The technical material here is vital and central to those people, esp. kids, who have been seriously traumatized and deformed by circumstances beyond their control like poverty and violence.  But it's unlikely they will read the basic technical article or even YouTube conversations like the one at: https://www.youtube.com/watch?v=80FODI0hXUw.  

In case you want to and don't have a med school education, this is a reading help: definitions, background, etc.

1.  Autonomic nervous system:  Previously a two-part system, mostly unconscious, where two halves are balanced against each other.  Now we find there is a third part, a whole separate system, and that's what all the commotion is about.

2.  Afferent influences:  Afferent and efferent are about nerve messages going into the brain and coming out of the brain.  There is active exchange both ways in this third system.

3  Adaptive reactivity dependent on the phylogeny of the neural circuits.  Evolution does not mean taking a new start, but rather building on what is pre-existing, possibly converting it for a new use.

4. Interactive with source nuclei in the brainstem regulating the striated muscles of the face and head.  This means it is about conscious movement when we make faces, either responding to emotion or expressing emotion.  Striated muscles are conscious -- we know we are moving them -- but smooth muscles are not -- they are unconscious.  Nevertheless, striated muscles can be acting in the face without the person realizing it.

5. Phylogenetic shift between reptiles and mammals -- from dorsal motor nucleus of the vagus in reptiles to the nucleus ambiguus in mammals.  Phylogenetic shift is a major change in life forms, major evolution.

6.  This resulted in a social engagement system that would enable social interactions to regulate visceral state.  A step forward for survival.

When someone we like smiles at us, we feel better. If they scowl, we react.  This is the kernel of empathy, which allows us to co-feel much more.

The early clue that researchers were following was "respiratory sinus arrhythmia" to monitor the stress of babies.  It's not the heart beat alone but in relationship to breathing.  At the other end of the age range, "Bradycardia is a heart rate that's too slow. What's considered too slow can depend on your age and physical condition. Elderly people, for example, are more prone to bradycardia. In general, for adults, a resting heart rate of fewer than 60 beats per minute (BPM) qualifies as bradycardia."

"The polyvagal theory articulates how each of three phylogenetic stages in the development of the vertebrate autonomic nervous system is associated with a distinct autonomic subsystem that is retained and expressed in mammals. These autonomic subsystems are phylogenetically ordered and behaviorally linked to social communication (eg, facial expression, vocalization, listening), mobilization (eg, fight–flight behaviors), and immobilization (eg, feigning death, vasovagal syncope [fainting], and behavioral shutdown)."  This is why "talking cures" work.  Even the strategies that use imaginary talks with some aspect of what is feared or hated can engage social mobilization for support and resolution.  Like prayer.

"Only mammals have a myelinated vagus." Myelinated means the nerve is insulated with fat, more heavyduty.  This explains why you can speak reassuringly to your dog, but not to your lizard.  If there is no one to activate this, the animal in danger will go to older behavior present in earlier creatures, like fight or flight.  But oppositely, if the situation seems safe. it encourages visceral homeostasis, the state best for growth and healing.  It's related to "liminal space."  This is physical, neither mystical nor psychological.  It will show in your face, eye gaze, listening and prosody.  (Prosody is about the poetic and musical elements of speaking or singing.)  

So now you know why church congregations and choirs require members who have myelinated vaguses and what wolves are really doing when they howl together.  It is a higher evolved power that knits them together socially.  This is quite enough to ponder for now.