Our brains are built to manage threats in ways that are sometimes beyond our conscious control. It can help to know this, prone as we are to criticize the ways in which we've responded to, and been 'marked' by, traumatic experiences. Under threat the nervous system functions in a largely involuntary way, and the moves it makes at those times, without our help, leave their signature in particular ways.

Polyvagal Theory
In his book Polyvagal Theory (2011), distinguished scientist Dr Stephen Porges 
has revealed the workings of neuroception - the brain's surveillance system that does not need our decisions for its operations to run. He reveals how our responses to danger are not deliberated by our thinking brainbut recruited by the autonomic nervous system from a small (but slightly larger than previously thought) menu of options. 

This, perhaps, is close to what we mean when we say that we 'lose our heads' in a crisis, or 'we didn't have our thinking caps on'. It's our shorthand for saying that the autonomic nervous system deploys its strategies without our deciding about it. It's a bit like the anti-virus checker on a PC. It does its detection work without prompting and deals with threats autonomously, according to its own rules for the wellbeing of the system.

Trauma as a Matter of the Brain
Anne Michaels, one of the world's great literary renderers of the ravages of trauma, catches hold, here, so vividly of how traumatic experience is as much a matter of the brain as it is a lived experience:
"No one is born just once. If you're lucky, you'll emerge 
again in someone's arms; or unlucky, wake when the long tail of terror brushes the inside of your skull." (2009:5)

Our human reactions to triggers get a lot of bad press. For many they're disgraces to be trashed or overcome. Understandable, given how distressing the patterns of reactions to triggers can be after trauma. The fallout can be mammoth. But it can help to recognize that autonomic responses to threat are in actual fact a remarkable compendium of safeguards crucial to our survival. Once we appreciate that safety measures are deployed without our conscious input, we can start to regard them differently. For Porges, a good deal of self-healing occurs when people adopt a more realistic view of the nervous system as trying to do its best for us. And so he says: "There is no such thing as a bad response; there are only adaptive responses." (NICABM Teleseminar: 20) 

Our Remarkable Defense Hierarchy
Porges' Polyvagal Theory has revealed that fight / flight are not the sum of our stress responses, but that we have two additional defense modes: social engagement and shutdown. Both these systems are located on the tenth cranial nerve, the vagus. The vagus is mainly a sensory nerve, travelling down from out of the brainstem through a good deal of the body and sending sensory information about the internal organs to the brain. It is capable of bringing changes to our physiology very fast. According to Porges, our three human response modes for keeping safe form a hierarchy of options, from which our nervous system selects its response to danger preferentially from 1 down to 3 (NICABM Teleseminar: 5-12): 

1 The social engagement and connection system is the one we humans employ most readily. When under threat, we try to find safety by connecting as a first-line operation. This social engagement system is linked in the brain to areas that regulate facial expression and vocalization, connecting the muscles of the eyes, mouth and middle ear with the heart. In evolutionary terms the social engagement system, which is unique to mammals, is the most evolved strategy for keeping safe. When this system is online, we feel calm, we make facial contact with people. 

2 Fight or flight response is the strategy we recruit when social engagement is not an option for our safety. When fight or flight mode is selected, metabolic activity increases as we mobilize for combat or retreat.

3 At the bottom of the hierarchy, we resort to shutdown when neither social engagement nor fight or flight are viable responses to the threat. In evolutionary terms, the shutdown response is our oldest system, and a remnant of a reptilian brain. Shutdown puts the body into a very particular physiological state, depressing metabolic activity. Fainting, 'numbing out' or dissociating are states associated with this mode. It's the mode of not being there whilst having to be there, under severe threat.

Not only does our nervous system make deployment decisions without our help, says Porges (NICABM video), it can also respond to threats in ways that actually run counter to our conscious intentions. To illustrate this, he describes his own experience during an MRI scan. At a conscious level he had been keen to have the MRI - after all, he's a brain scientist! - but once inside the enclosed scanner he had an unexpected panic attack. Because, he explains, the mammal has difficulty immobilizing without fear. After the event Porges felt - as do many people post trauma, that his nervous system had let him down. People who, for example, immobilized during a trauma may look back on things self-critically, believing that they ought to have "done something", particularly in cases where other people suffered. But, in fact, they could not, because the nervous system was making its own emergency selection in the interests of safety, without their consent. When the ancient vagal shutdown circuit is triggered, Porges tells us - and this is likely to happen when people cannot take effective action to ward off what is happening to them - we don't have much control. On the plus side, one of the benefits of the ancient reptilian vagus is that it can "change how we experience a traumatic event including raising our pain threshold." (NICABM teleseminar: 10)

Re-thinking Our stress Responses
Polyvagal Theory is a re-evaluation of our responses to threat as adaptive. People who have lived in relentlessly dangerous situations may well have developed either fight or flight, or shutdowm, as fallback measures in a dangerous world, perhaps getting "stuck" in these modes. (See more in Psychotherapy Networker.)

In this context, our particular metabolic predispositions start to 
make more sense: how it is that we may be patterned for metabolic acceleration, or deceleration, or some kind of vacillation between these states. The body becomes, in this way, a faithful carrier of itself, impressioned upon by its particular experiences. Trauma specialist Bessel Van Der Kolk captures this idea so well in his choice of book title The Body Keeps The Score (2014).

Social Engagement For Safety 
In the context of therapy and counselling, I think Polyvagal Theory provides some clues about why some clients do less well with especially reserved therapists. People for whom social engagement has generally not triumphed for their safety, are very likely going to need readily discernible connection cues from the therapist, signals that could be vital to engage the neural circuitry that needs to come online in order to feel safe. "We do know," says Porges, "the features of neuroception that trigger the social engagement system, the uniquely mammalian part of our autonomic nervous system that enables social interactions to calm our physiology and to support health, growth, and restoration." (NICABM Teleseminar: 11) 

Safety experienced in relationships is good news for our neural circuitry. The crux of it, in polyvagal terms, is that "If we are protected with the newer vagal circuit, we do fine. However, If we lose regulation of this newer [to mammals] vagal circuit, we become, in a sense, basically defensive fight-flight machines." (NICABM Teleseminar: 10)

Like alarms set with hyper-sensitive surveillance, 
there is repeated 'tripping' of the system in response to triggers that cue in, but no longer necessarily represent, actual present-time danger. Over-recruited survival responses can become like an operating system that runs relentlessly without showing an 'uninstall' option.

People who have had to recruit shutdown time and again, may well have developed zoneout as a protective pattern. On the hierarchy of threat responses, this is the furthest away from social engagement, which explains why in dissociated states, people feel so very far away from feeling connected. They are!

In order to select which response to recruit in a situtation, the nervous system must detect the relative danger. At a neurophysiological level there seems not to be certainty about how this selection happens - because the same event will trigger different stay-safe responses in different people - but the speculation is that early experiences affect the selection threshold (Porges: NICABM teleseminar: 9). Attachment histories and exposure to traumatic events seem so relevant here.

Sound's Potential as Soother
Porges has found that sounds are an especially potent trigger of neuroceptive responses. Think of the potential of lullabies to soothe, as compared with sudden loud noises that jolt and upset. This could explain, at least in part, why singing, whistling, laughing, chanting mantras help people to feel more at ease. Thanks to its findings about the effects of vocalization, Polyvagal Theory has huge promise for the treatment of autism. The theory suggests that engaging the middle ear muscles - which are important in extracting human voice from background sound - can help people become more spontaneously social. An effective listening project run by Dr Porges uses prosodic features of human voice to encourage the nervous system to trigger states of safety.

Basic First Aid for PTSD & Autism
For Porges, doing the things that change physiology is key to creating new possibilities in a number of situations, including autism and PTSD. “What I see as the most profound way of engaging many individuals who have various disorders," he suggests, "is to functionally change the physical context. Get rid of low-frequency sounds; enable music or melody to engage people using prosodic voices, voices with great intonation, don’t bark at people. Do not treat people as if their disorder is a decision to be compromised, but really is an expression of a physiological state that they are in.”
(NICABM Telesiminar: 19)

Back to the beginning. Taking stock of our 'hardware', with which Polyvagal Theory helps a great deal, does no harm. It reminds me of the sense of consolation that Irvin Yalom conveyed when he recalled a comment made by his own analyst: "That seems to be the way we're built." *
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*
I recall - perhaps erroneously - having once seen this citation in one of Yalom's collections of stories about psychotherapy, and at the time it reached me as a consoling piece of realism (although it wasn't said in the context of brain science, but more generally in the context of our as-it-is and less-than-flawless humanity). In trying to track its origin down, I found it re-cited here.

RESOURCES

Stephen Porges is interviewed about Polyvagal Theory in this YouTube video:

Stephen Porges Website:
http://stephenporges.com/

The National Institute for the Clinical Application of Behavioral Medicine website features a number of videos in which Dr Porges speaks about trauma:
http://www.nicabm.com

REFERENCES

Bergland, C. (2014) How Does the Vagus Nerve Convey Gut Instincts to the Brain? in Psychology Today. Retrieved June 15 2016, from  https://www.psychologytoday.com/blog/the-athletes-way/201405/how-does-the-vagus-nerve-convey-gut-instincts-the-brain

Michaels, A. (2009) Fugitive Pieces. Bloomsbury.


National Institute for the Clinical Application of Behavioral Medicine (NICABM) (n. d.). The Ployvagal Theory for Treating Trauma. Transcript of A Teleseminar Session with Stephen Porges and Ruth Buczynski.

National Institute for the Clinical Application of Behavioral Medicine (NICABM) (n. d.). The Polyvagal Theory: Looking at Trauma through a New Lens.  Video material retrieved June 14, 2016, from http://www.nicabm.com/the-polyvagal-theory-looking-at-trauma-through-a-new-lens/ 

Porges, S. (2011) 
The Polyvagal Theory: Neurophysiological Foundations Of Emotions, Attachment, Communication, and Self-Regulation. WW Norton.

Howes, R.
 (n.d.). Rethinking the Autonomic Nervous System. Stephen Porges on a Popular Neuroscientific Misconception in Psychotherapy Networker. Retrieved June 15 2016, from https://www2.psychotherapynetworker.org/home/tag/polyvagal-theory/

Van Der Kolk, B.A. (2014) The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma. Penguin Books.