Pain and the Brain by Dr Sue Bagshaw
Fifteen Years of Explaining Pain: The Past, Present, and Future. G. Lorimer Moseley and David S. Butler. The Journal of Pain, Vol 16, No 9 (September), 2015: pp 807-813. Available online here.
This paper was a fascinating one for me as it brought together many of my thoughts around our perception of pain both physical and emotional, and the development of the way we learn how to think between birth and adulthood.
There are all sorts of pain, some sensations of pain are sometimes perceived as pleasure, but usually pain is a warning of danger. It seems to me, sensory input requires a cognitive explanation, which is very much driven by context and past experience. This “explanation” to ourselves might be conscious or subconscious.
According to the latest theories the brain works by predicting a need, developing a solution and if that doesn’t fit then trying again. This is known as prediction error which is actually a statistical term meaning to find the best fit. So, information comes in and the difference between that and what we expected or predicted is noticed and the next best guess is formed.
As the Brain is developing and “switching on’ it creates pathways. Alterations occur in the internal ebb and flow of electrons and chemicals. How does it know which information is internal and which is coming in from outside and therefore what appropriate response to make? The theory is that it is done by using best guesses – predict something if it works, great – if not try another model. To make a guess the brain uses previously discovered priors. When a baby learns what a chair looks like they only have to notice differences to learn about different sorts of chairs, which saves time. When a child gets its own way by screaming the place down then they continue to do so until that approach doesn’t get their own way.
This completely ties in with what philosophers have said from Plato to Locke to today in terms of their thoughts and observations about how the mind interacts with the world, now translated into the scientific description of how that happens. To sum it up – what we see and hear is what we think we are going to see and hear as programmed by our culture, epigenetics, genetics and personal experience.
Vygotsky was a Russian Jew who lived before, during and after the Russian revolution who developed a theory of development which saw the brain being formed with some basic abilities at birth, but which developed via:
- learning from another (both adult and or child),
- the symbolism of language and
- action based experience.
These led to learning and the development of abstract thinking. He felt that helping people to make sense of what is going on and understanding the meaning of their experiences was essential. Each stage helps the next stage in a process he called scaffolding. Lisa Feldman-Barret’s book on how emotions are made talks about the growing ability to make meaning out of feelings and sensory perceptions, as paths develop through the limbic system to the cortex.
“As strange as it sounds, when your own behaviour is involved, your predictions not only precede sensation, they determine sensation. Thinking of going to the next pattern in a sequence causes a cascading prediction of what you should experience next. As the cascading prediction unfolds, it generates the motor commands necessary to fulfil the prediction. Thinking, predicting, and doing are all part of the same unfolding of sequences moving down the cortical hierarchy” Hawkins and Blakeslee (2004) p.158
The brain seems to operate a prediction error minimization strategy. So how does this relate to the feeling of pain?
When I was a medical student, we were taught Wall’s gate theory of pain sensation. The rough outline was that input from sensory organs – eyes, ears, nose, touch receptors in the skin and receptors in joints and muscles etc follows nerve pathways into the spinal cord and could be stopped at that level by inhibition stimulus. Inhibition was affected by a variety of factors, but the cortex wasn’t really involved. The TENS machine was built on this theory in terms of tapping the skin at another place from where the pain is coming from, to increase inhibition of the pain stimulus at the spinal cord level. For example, if there is chronic pain from arthritis if you tap the chest with the little machine at certain frequencies that distracts from the pain. This concept of distraction from pain grew as it was realised that the brain higher than the spinal cord is involved in pain sensation, so thought could be involved in distraction techniques.
If this is then merged into the theory of predictive error, perhaps we can use it to make sense of our experience of pain as in the explanation of pain in the paper. The experience of pain becomes a mechanism for self-protection which can in turn be altered. Sensory input goes to the brain and is compared with information already learnt as the baby learnt about the image of what a chair is and then alters it to fit another name when it only has three legs. A prediction is made about what is unknown and not comparable to what has been already learnt. For the baby the action suggested is to find a new name, or not use it as it might fall over. In the case of pain the action is to find out more about the cause of the pain and then not repeat the action that gave rise to the pain sensation. If the source of the pain is memory of the cause, especially in the case of emotional pain, then re programming the brain is required to learn that the memory is not pain.
If we think about it like this, maybe we can learn to live without pain in spite of information from sensory input as we learn to reinterpret what that pain means. It’s easy to see that the sensation from your finger, when it touches a hot stove, tells you to take your finger off the stove. It’s not so easy with emotional pain, when your memory tells you that the bad things that happened to you are never going to stop. The pain inflicted by whatever the abuse was is still reverberating around the pain circuits in the brain. If we could stop the circuit by learning to change the pathways then that might work much better than distractions the brain uses like a panic attack or when we use alcohol or other drugs.
Easier said than done but maybe worth a try!
Just some thoughts that I am hoping might stimulate your thoughts.
Hawkins, J and Blakeslee, S (2004) On Intelligence (Owl Books, NY) quote found in : Clark A (2013)Whatever Next? Predictive Brains, Situated Agents, and the Future of Cognitive Science University of Edinburgh. Behavioral and Brain Sciences · May 2013 DOI: 10.1017/S0140525X12000477 · Source: PubMed https://www.researchgate.net/publication/236689333
Lisa Feldman-Barret How Emotions are Made. 2017 Houghton Mifflin Harcourt New York, McMillan UK ISBN978-1-5098-3750-2
Jaramillo, James A. "Vygotsky's sociocultural theory and contributions to the development of constructivist curricula." Education, vol. 117, no. 1, 1996, p. 133+. Accessed 6 Apr. 2020.
Sociocultural approaches to Learning and Development: a Vygotskian Framework, Vera John-Steiner and Holbrook Mahn https://www.tlu.ee/~kpata/haridustehnoloogiaTLU/sociocultural.pdf