The paper, Pain.
Part 1 First two sentences
Part 2 Pain is personal
Part 3a Pain is more than sensation: Backdrop
Part 3b Pain is not receptor stimulation
Part 3c: Pain depends on everything ever experienced by an individual
Here are the next two sentences of the abstract.
"The neuromatrix theory guides us away from the Cartesian concept of pain as a sensation produced by injury, inflammation, or other tissue pathology and toward the concept of pain as a multidimensional experience produced by multiple influences. These influences range from the existing synaptic architecture of the neuromatrix—which is determined by genetic and sensory factors—to influences from within the body and from other areas in the brain."
Recall that Gifford proposed that the brain was a "stress response coordination center" with outputs out along systems that included a basic four: somatic motor, autonomic including enteric, neuroendocrine and immune. Following evolutionary trails carved deep into scientific terrain, Gifford points out, look: organisms that survive add that survival strategy, all the way from cellular to organismal, to their bank of output behaviour possibility. Maturation at a biological level means a system that has learned lots of ways of coping. Pain is one way of coping... When we treat people, as therapists, we would do well to consider deeper biological meanings of pain as an output.
Melzack, who did lab research for decades, held burning matches underneath the noses of Scottish terriers reared in isolation and carefully observed their behaviours, finally came up against some kind of internal wall, which forced him to conclude, in four different ways, look: when we view "pain" as something that starts in a body and ends up in a brain, it just doesn't make any sense. That frame is way too simplistic. Here is some evidence, based on studies of paraplegics whose [supposedly!] offending ascending systems were completely silenced, and they still had phantom, body pain, of the most excruciating kind. How do we account for that? How?
Here's another thing: experience leads a biological organism, like a complex vertebrate mammal creature, to develop "filters" to input from the environment. His dogs didn't develop ordinary filters. Their brains didn't neuroplasticize normally, i.e., didn't develop filters, because the dogs were reared in isolation. As quoted in the book, The Ontogeny of Vertebrate Behavior, Melzack says:
A two-part process in which (a) there is inadequate filtering of inputs on the basis of memories (phase sequences) of the significances of stimuli normally acquired in early experience, so that (b) the total input bombarding the central nervous system produces an excessive central nervous system arousal which, as Hebb (1955a) has suggested, could be responsible for the correspondingly low cue properties necessary for discrimination and adequate responses (1965, pp. 276-277)Filtering? Filters... hmmn.
So... really, there might be another layer here. Let's think about this - if a person hasn't had much rough and tumble as a child (like, exposure to dirt, other children, physical contact, e.g., the feeling of body weight through bare feet against cool grass or warm rock or slippery mud puddle or rough gravelly dirt or sharp prairie cactus) their brain won't have learned, perhaps, how to filter out (possibly noxious) physical input in the ordinary context of having simple childish fun.
Mammal babies all play. Kittens, puppies, bear cubs, baby primates - attack each other (or some convenient parental tail) - bite, scratch, hunt each other, roll all over the ground, over sticks and stones, over embankments, fall off tree limbs.. I submit that mammal children aren't just training their somatic motor output systems - in the context of having psychosocial fun, their other output systems (see Gifford) are being trained up as well.
What are human children physically exposed to anymore? Is gravel still allowed on playgrounds?
Probably in most places in the world, children are still allowed to take their own personal lessons from ordinary physical exposure to their environment, hard edges and all. But I do wonder sometimes about the sanitized world of the modern westernized urban parent/child.
The culture. It comes back to the culture.... sometimes I wonder, could this epidemic of chronic pain have anything to do with this culture having raised us like hot house flowers?
Here is the final sentence of the abstract - yeah, we made it! To the end of the abstract. Finally.
"Genetic influences on synaptic architecture may determine—or predispose toward—the development of chronic pain syndromes."This is the only "bio" factor that has any real meaning, in my own humble opinion.
Absolutely, if you are a child born without the ability to provide your hungry little brain with any nociceptive experience, it won't be able to learn how to protect you from your environment - your critter brain won't be able to teach you painful lessons. Here is a link to the (misnamed, according to me) CIP page.
CIP stands for "Congenital Insensitivity to Pain." I think it should be renamed CIN, Congenital Inability to Nocicept. Or else add an S on the end, and call it Congenital Insensitivity to Painful Stimuli. Just to be clear.
But such children's brains are still primed for learning about and responding to noxious stimuli, still react when they see pain behaviour in others. See Danziger et al., "Can we share a pain we never felt? Neural Correlates of Empathy in Patients with Congenital Insensitivity to Pain", Neuron (2009), 61(2):203-12. Their critter brains are, at least. Posted to The Girl Who Feels No Pain.
If CIP is a condition or a group of related conditions, one can imagine a large range of genetic capability or non-capability to transduce nociceptive stimuli, including perhaps, conditions where someone might be born with..
1. way more nociceptive fibres than usual
2. way too many of one kind but not enough of some other kind
3. the usual number and array but they make way too many receptors in response to ordinary stimuli
4. the usual number but don't take down receptors once they've been built
5. the usual number but way too many microglia in the spinal cord that get way too busy
6. the usual number but not enough interneurons of the right kind at the central terminal
7. some kind of wonky malformed neurotransmitter molecule that doesn't work right or works way too well
8. countless more ways the peripheral and central nervous systems can't quite figure out how to talk to each other harmoniously because of some little genetically produced molecular deficiency or excess or possible epigeneity.
But maybe everything was genetically set up to be perfect:
Maybe there are developmental windows a normal system has for learning, like the window that exists in a child for learning a second language without an accent, up to age 7 or something. Maybe people miss windows. So maybe there may be the usual number of both nociceptive capable neurons and microglia and everything else in the right proportions, but in a person with a system which never was allowed to build a normal robust response to ordinary environmental physical input.
These are the sorts of things I think about all the time. I know people are working out answers, collecting data, deciphering statistical information, putting out graphs, having conferences, showing each other slides. I know they are trying. My fantasy is that some day everyone will know everything about everything to do with pain. But it won't happen in my lifetime. Of that I am quite certain.