Sunday, May 11, 2014


My take on why manual therapy "works", part 3.



Moving on to point 2 and 3 in the little SomaSimple post list:

2. Something new has to be added for the brain to get busy with. Manual contact provides it a way to distract itself from the unfortunate neurotag, long enough to get itself started on building a new representation of somatic "reality" - a new neurotag.
 3. The old one will never go away, but the brain can now "choose" to adapt itself to the new one. It's called extinction learningand happens at the receptor level of brain operation. Once that happens, old triggers are no longer triggery

What do I mean by that? It's a pretty compact statement to make. There is much to unpack in it.
Let me try.

First off, I've convinced myself there are at least two brains in there, critter and human:
1.  critter brain, mostly interoceptive, an internal regulation system, all the brain stuff that works from day one when we are born, even if it takes a bit longer to mature in some aspects. All the brain nuclei that keep us alive, as individuals, and later, come online to keep us alive as a species.  The part of the brain that is born knowing how to swallow, blink, burp, throw up, breathe, sleep; it's the brain that puts us to sleep at night, but keeps our heart beating and our lungs breathing. Rolls us over in the night, hopefully without waking us up. Wakes us up in the morning because it's hungry and wants us to go get it something to eat. It's the brain that runs our blood flow, our temperature, our immune system, our descending modulation to nociceptive input. It started out as a spinal cord, invented by fish, half a billion years ago. The front end of it added more hard drive as critters became more complex, faced more complex challenges, like gravity, by adapting movement behaviour to physical forces, couldn't reproduce anymore just by squirting out eggs and sperm into the water and hoping they bumped into each other. We still have all that stuff, because nature never throws out anything that works - it just adapts it to new purpose, an evolutionary principle known as exaptation.
But be aware, the spinal cord, even though it doesn't have much hard drive, at ALL, will automatically take care of motor output business reflexively, whenever it can - that is to say, whenever it isn't being tonically inhibited by more rostral centers. Uh-oh - more words..
"Tonically" means continually. As opposed to "phasically", which means in a punctuated manner. These words crop up all the time when you read about the brain(1).

Tonic would be like holding your hand under a dribble of water flowing continuously from a tap. Phasic would be one drop of water falling on your hand, then another, indefinitely(2). EXAMPLE: 

"Second, inhibition can be "phasic" or "tonic". Phasic inhibition is a short-lasting inhibition typically generated by the activation of GABAA receptors following action potentials in a presynaptic interneuron. However, there are also more long-lasting forms of inhibition. One form is the activation of GABAB receptors by spillover of GABA caused by GABA release from specialized interneurons. A second form is the "tonic" GABAA conductance activated by ambient GABA in the extracellular space (Farrant and Nusser, 2005). This form of inhibition is mediated by molecularly and functionally specialized GABAA receptors(2)."
2. a human brain, externally driven, mostly exteroceptive, dependent on social relations and symbolic thought, the one "we" live in and consider as "I". This consists of the expansion of frontal lobes and the association cortices. The one that makes up rules to live by in consensus with other human primates, then decides that's the "right" way to live and everyone who doesn't is by definition "wrong" (or at least suspicious..)
The human brain can be taught how to be more aware of interoception.

Anyway, I'm not entirely sure, but pretty confident, that in the case of pain, it's the critter brain that "makes" it, or else just doesn't inhibit nociception in a timely or effective manner, then sends it forward or else simply lets the info travel all though the brain, including to the "conscious awareness" bits, where the human brain "perceives" it.

I see my job as distracting the one while competently handling the other, so that the two might live together in harmony once more, through new learning. Each learning episode seems to take at least two minutes. I don't think any lasting change can happen in there in any shorter length of time.

Here is where I'm just making stuff up: I can't prove any of this, all I can do is write about my thought process.
There are many types of learning.
Here are a group of blog posts on the topic, from Neurotonics, which developed from this one by Matthias Weinberger, The Devil is in the Details.

I think the kind I favour for the process of manual therapy learning, kinesthetic learning, is extinction learning (3). I have no idea if it's the case, but it makes sense to me. Pain becomes tied up in fear. Fear (of moving) is involved. Fear (of moving) must be disengaged. The brain makes a new representation of its "bodymaps"every couple nanoseconds (4). 

Stress is involved in "learning" - the right amount of glucocorticoids will facilitate learning. Too much will be harmful. "Pain" is "learned" at a synaptic level. "Pain" is reinforced through social stress, be it real or just perceived. (Which means, for us independent human primate social groomers, we can give ourselves some leeway - there are some pain mountains out there that we just aren't going to be able to climb. We can't fix some of our patients' broken lives. Furthermore, some people's pain, even though it may be biopsychosocial, may have abnormal "bio.")

If you can provide a patient's human brain with a window of relief, in which it can move its physicality freely again, and it's a normal intact brain, it will rapidly accept/learn the new representation. Positive feedback loops are interrupted.
The human brain can get back in charge of the critter brain. It will take back its right to move its physicality, easily. Like water rolling down a hill. Critter brain will have stopped "biting" the human brain.

So, it's the critter brain we want to distract. How? By offering a new input. It's kind of automatic that the critter brain's salience network will come over to sniff out a new input, even innocuous. Meanwhile, we are not doing anything the human brain finds the least bit uncomfortable. Or at least we shouldn't be, in my opinion. 

The human brain is in on the plot to contain the critter brain, because we provided it with information at the start. In this way, we can work together (psycho-social) to overcome the critter brain (bio), from top down and bottom up at the exact same time. The therapist helps from the outside by creating the treatment context, a story-line maybe, maybe about helping move/feed/drain nerves or something (that's the one I use all the time). But the patient's human brain will be doing all its own heavy lifting/changing/neuroplasticizing around the new input. 

1. Mark Farrant, Zoltan Nusser; Variations on an inhibitory theme: phasic and tonic activation of GABAA receptorsNature Reviews Neuroscience 6215-229 (March 2005)
2. Neural inhibition. Peter Jonas, Gyorgy Buzsaki, Scholarpedia page
3. Edwin Santini, Robert U. Muller, and Gregory J. Quirk; Consolidation of Extinction Learning Involves Transfer from NMDA-Independent to NMDA-Dependent Memory. The Journal of Neuroscience, 15 November 2001, 21(22): 9009-9017 4. Notes re: Interoception, from A.D. (Bud) Craig's lecture.

No comments: