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The personal experience of pain produces a reliable effect on facial behavior in humans and in nonhuman mammals. Why should pain have a face? What is it for? I will attempt to head towards answering this question by invoking a theoretical framework: polyvagal theory (Porges, 2001, 2006).
1 Polyvagal Theory
According to polyvagal theory (Porges, 2001, 2006), evolution of neural control within the autonomic nervous system (ANS) has tracked three stages, each revealing a specific behavior, and a specific function:
In the first stage, the ancient unmyelinated visceral vagus nerve that enables digestion could respond to danger and pain only by reducing metabolic output and producing immobilization behaviors.
In the second stage, the sympathetic nervous system (SNS) made it possible to increase metabolic activity and inhibit the visceral vagus nerve, thus allowing fight/flight behaviors following perceived threat or pain.
The third stage, which is uniquely mammalian, involves a myelinated vagus that can rapidly control cardiac and bronchi output to enable spontaneous interaction (i.e., engagement or disengagement) with the environment. The interaction of the autonomic nervous system (ANS) with the hypothalamo-pituitary-adrenal (HPA) axis, nervous and immune systems change to maximize response to stressors such as nociception. During nociception, the ANS operates together with nervous, endocrine and immune systems to produce stress (Chapman et al. 2008; Porges, 2001, 2006). In terms of polyvagal theory, pain facial expression is a dynamic autonomic response caused by noxious signaling. In terms of polyvagal-type identity mechanistic theory pain facial expression is a type of behavior that is identical to a type of neurophysiological mechanism; namely, the phylogenetically recent brain-heart-face mechanism.
The expansion of cortex in the third stage increased innervation and neural control of the mammalian face: upper face innervation is bilateral and arises from the supplementary motor area (M2) and the rostral cingulate motor area (M3). Lower face innervation is contralateral and arises from primary motor cortex (M1), ventral lateral premotor cortex, and the caudal cingulate motor cortex (M4) (Morecraft et al. 2004). Human pain facial movements of the eyebrows and upper lip are type identical with negative emotional aspects of pain and activation of M1, M2, M3, whereas facial movements around the eyes are type identical with somatosensory aspects of pain, and activation of M2 and M3 (Kunz et al. 2011). Thus, evolution of cranial anatomy enabled a highly integrated facial representation of the multidimensional experience of pain.
2 Why Pain Should Have a Face
In clinical and experimental settings, the pain face is observed to rapidly appear following noxious stimulation, and diminish concurrent with cessation of the noxious stimulus, or when analgesics are administered (e.g., Craig & Patrick, 1985). The brain-heart-face mechanism is an integrated system with both a somatomotor part controlling the striated facial muscles and a visceromotor part controlling the heart through a myelinated vagus nerve (Porges, 2001, 2006). When the vagal tone to the cardiac pacemaker is high, the myelinated vagus acts as a brake or restraint limiting heart rate. Rapid inhibition and disinhibition of vagal tone to the heart supports the rapid mobilization of facial muscles and formation of the pain face concurrent with pain onset. In humans and nonhuman mammals, the main vagal inhibitory pathways in the myelinated vagus originate in the nucleus ambiguus.
The vagal brake supports the low-metabolic requirements involved in the rapidly appearing and disappearing pain face. Withdrawal of the vagal brake is strongly correlated with the rapid appearance of the pain face; reinstatement of the vagal brake is strongly correlated with the rapid diminishing of the pain face. These correlations are not unique to pain facial expression; similar relationships hold with regard to the vagal brake and the timing and duration of aversive, but non-noxious emotional facial expressions (e.g., Pu et al. 2010), and positive emotional facial expressions (e.g., Kok & Fredrickson, 2010).
In terms of the function of rapid pain face onset and offset, the vagal brake makes it possible for the individual in pain to quickly disengage from source of wounding and pain, concurrent with the rapid appearance or diminishing of pain facial expression, which may offer temporary access to additional metabolic resources to aid healing, recovery and self-soothing behaviors, with likely involvement from care givers.
Concerning aid from others, the vagal brake reliably maps onto specific interaction types observed in mammalian pain events. In pain events comprising the individual in pain and care givers, mammalian behavior is typed according to interpersonal communication through facial expressions, vocalizations, head and hand gestures (Hadjistavropoulos et al. 2011; Porges, 2001, 2006; Williams, 2002). A relevant feature is the rapid ‘switching’ of temporary engagement to temporary disengagement behaviors between the individual in pain and care givers. This interaction type may involve care givers speaking to the one in pain, and then quickly switching to listening; for the one in pain, looking into the face of the care giver, and then quickly switching to vocalizing (Craig et al. 2011; Hadjistavropoulos et al. 2011; Porges, 2001, 2006; Williams, 2002). The brain-heart-face mechanism thus allows the one in pain and the care giver to get the timing right. Some philosophers and neuroscientists claim that evolutionary neurobehavioral solutions to timing problems such as these are implicated in the origin of empathy and ultimately consciousness itself (Churchland, 2002; Cole, 1998; Engen & Singer, 2012; van Rysewyk, 2011).
However, if pain is severe or chronic and the vagal brake is withdrawn (or dysfunctional), the concurrency of increased pain facial expression, cardiac output, and other mobilization behaviors (i.e., increased SNS and HPA output), means that, if care giving is to succeed in promoting healing and recovery, the care giver’s vagal brake must be dynamically reinstated. By applying their own vagal brake, care givers may regulate their own visceral distress and thereby succeed in allocating valuable metabolic resources to communicate safety to the one in pain (and themselves) through calming facial and head behaviors, eye gaze, and prosodic vocalizations (i.e., increasing the vagal brake decreases SNS and HPA output). Since the vagal brake of the person in pain has been provisionally withdrawn, the care giver is effectively an integrated external brain-heart-face mechanism (cf. Tantam, 2009, the ‘interbrain’).
Thus, the pain facial muscles function as neural timekeepers detecting and expressing features of safety and danger that cue the one in pain to quickly disengage from the source of wounding and pain, simultaneous with the rapid appearance or attenuation of pain facial activity, and also cue others who can help.
Chapman, C. R., Tuckett, R. P., & Song, C. W. (2008). Pain and stress in a systems perspective: reciprocal neural, endocrine, and immune interactions. Journal of Pain, 9(2), 122-145.
Churchland, P. S. (1989). Neurophilosophy: Toward a Unified Science of the Mind-Brain. Cambridge, Mass.: MIT Press.
Cole, J. (1998) About face. Cambridge, Mass.: The MIT Press.
Craig, K. D., & Patrick, C. J. (1985). Facial expression during induced pain. Journal of Personality and Social Psychology, 48(4), 1080-1091.
Craig, K. D., Prkachin, K. M., & Grunau, R. E. (2011). .The facial expression of pain. In D. C. Turk, & R. Melzack, Handbook of Pain Assessment, 2nd Edition (pp. 117-133). New York: The Guilford Press.
Engen, H. G., & Singer, T. (2012). Empathy circuits. Current Opinion in Neurobiology, 23, 1-8.
Hadjistavropoulos, T., Craig, K. D., Duck, S., Cano, A., Goubert, L., Jackson, P. L., Mogil, J. S., Rainville, P., Sullivan, M. J. L., de C. Williams, Amanda C., Vervoort, T., & Fitzgerald, T. D. (2011). A biopsychosocial formulation of pain communication. Psychological Bulletin, 137(6), 910-939.
Kok, B. E., & Fredrickson, B. L. (2010). Upward spirals of the heart: Autonomic flexibility, as indexed by vagal tone, reciprocally and prospectively predicts positive emotions and social connectedness. Biological Psychology, 85(3), 432-436.
Kunz, M., Lautenbacher, S., LeBlanc, N., & Rainville, P. (2011). Are both the sensory and the affective dimensions of pain encoded in the face? Pain, 153(2), 350-358.
Morecraft, R. J., Stilwell-Morecraft, K. S., & Rossing, W. R. (2004). The Motor Cortex and Facial Expression: New Insights From Neuroscience. The Neurologist, 10(5), 235-249.
Porges, S. W. (2001). The polyvagal theory: phylogenetic substrates of a social nervous system. International Journal of Psychophysiology, 42(2), 123-146.
Porges, S. W. (2006). Emotion: An Evolutionary By‐Product of the Neural Regulation of the Autonomic Nervous System. Annals of the New York Academy of Sciences, 807(1), 62-77.
Pu, J., Schmeichel, B. J., & Demaree, H. A. (2010). Cardiac vagal control predicts spontaneous regulation of negative emotional expression and subsequent cognitive performance. Biological Psychology, 84(3), 531-540.
van Rysewyk, S. (2011). Beyond faces: The relevance of Moebius Syndrome to emotion recognition and empathy. In: A. Freitas-Magalhães (Ed.), ‘Emotional Expression: The Brain and the Face’ (V. III, Second Series), University of Fernando Pessoa Press, Oporto: pp. 75-97.
Williams, A. C. D. C. (2002). Facial expression of pain: an evolutionary account. Behavioral and Brain Sciences, 25(4), 439-455.
How do we think about reality in a way that improves upon the old ways?
There is good news here: it is not entirely up to you to improve reality. Your children, and their children will do the job. So, sit back a little. Enjoy the ride!
Human beings have the unique capacity to play life’s ‘ratchet game’. Children learn the best society has to offer, and can improve upon it. And, your children’s children can start where your children left off. And so on.
My kids are already way ahead of me, since they started where I left off long, long ago, and also vastly ahead of cro-magnon humans. By contrast, chimpanzees start where their ancestors left off, and stay there. They don’t move from this place (chimps are still very cute, though).
Thus, humans can produce science and technology, and pass it on to their descendents. This gives human beings the chance to deploy science and AI tech to create increasingly accurate representations of ‘mind’, ‘DNA’, ‘autism’, ‘pain’, ‘happiness’, and so on. The ratchet game takes us beyond the familiar into exciting new territories.
(I wonder: Can academic philosophy play life’s ‘ratchet game’? It seems to me that philosophy is not terribly good at reaching out to other disciplines, and learning from them in the way that children naturally learn from parents.)
I am too honest to be religious. Religion lains waste to honest reflection and questioning.
Many people claim to be religious. How many are pretenders?
There may be good reasons why a person pretends to be religious. A religious son adores his devout mother so much that he could not bare her to learn of his atheism. However, unknown to him and family, the mother is an atheist, and has been for decades. Like the son, she became a religious pretender in order to protect her mother’s feelings, and so on.
How to break this circle of lies? Honest reflection and questioning. And that takes great courage.
John Donne was partly right: A person is an island. But – every island is surrounded by water.
I am half myself, half you.
I am surrounded by your facial expressions. I adopt them as my own.
I cannot predict your every thought and action for the simple reason that most of my own thoughts and actions are completely spontaneous.
I cannot predict what I will do in most instances. I cannot know myself, so I cannot know you. True enough? We are both in the dark, it seems.
That sounds a bit bleak.
Is there any good news?
Yes: A person is not a vacuum. Human thought and action is shared. Shared, copied, modified, suppressed, distilled – we live in each other’s facial expressions.
I wake-up and tell my wife about the dream I had while sleeping. That’s a dream-report.
Dream-reports are given by the dreamer in the first-person present-tense. Even if I dreamed I had incarnated another person (either a real or imagined person), it is always I (the dreamer) who peers out from the face of the other person during the dream. And that’s what is communicated when I tell my dream to another person.
Why do human beings share dreams?
Sometimes a dream is amazing. Amazing that I could even dream up such an experience. What is important to human beings in this case is that the dream really did impress me. Dream-reports can be spontaneous responses to what we see during sleep. So: that I dreamt such-and-such is amazing and of more interest to other people than what the dream describes. Dream-reports can therefore function more like exclamations or interjections than descriptions of what the dreamer experienced.
However, the dreamer may sometimes become frustrated trying to communicate the dream in a dream-report. We try to describe what happened in the dream using the medium of language (the dream-report), but we cannot. The dream eludes the net of language. At least that’s how we feel. The dreamer is frustrated with language and may think that since the dream cannot be described, it points to something beyond itself. But – why must a dream be capable of being described? After all, can you describe all the experiences of your waking life? Try and do it. Why must dreams be any different? In life, human beings are both the way and the wayfarers.
For some reason, we see dream-reports as descriptions of dreams. We see them as fragments of a story we assume can be told in full. Yet, dreams cannot be described to our satisfaction. Frustrating. Frustration leads to puzzlement. Most of the time we are puzzled by dreams (our own, and those of other people). Why? – are dreams seen as mysterious because dream-reports are assumed to be descriptions of dreams?