Pain is a conscious experience, so in order to understand pain, we have to dive into how consciousness works. That is one of the reasons consciousness has been given some time in past posts on noijam (here, here and here for example).
One way to think about consciousness is as a controlled hallucination.
Not in a pathological way. Just in a way that is so fundamental to our experience and how we perceive our environment that it feels all too normal. At least that is Anil Seth's argument in his recent TED talk called “Your Brain Hallucinates Your Conscious Reality.”
Here’s three things that I took from the talk and how they relate to pain.
1) Perception is Based on a Best Guess
Lorimer Moseley has touched on the topic of perception being a best guess in his book Painful Yarns. One of the ways he did so was by using vision as a base for understanding perception, then applying the same concepts to pain. Seth takes this concept to an even more fundamental level and argues that not only is perception based on a best guess, but that it is a brain’s only option.
Here’s how Seth Explains it.
“Imagine being a brain. You're locked inside a bony skull, trying to figure what's out there in the world. There's no lights inside the skull. There's no sound either. All you've got to go on is streams of electrical impulses which are only indirectly related to things in the world, whatever they may be. So perception -- figuring out what's there -- has to be a process of informed guesswork in which the brain combines these sensory signals with its prior expectations or beliefs about the way the world is to form its best guess of what caused those signals. The brain doesn't hear sound or see light. What we perceive is its best guess of what's out there in the world.”
Day to day living doesn’t make it seem as if we are a brain locked in a bony skull, but it’s hard to argue that that is not what’s happening. I also like the acknowledgement that the information from the outside world comes in streams of electrical impulses that are only indirectly related to the outside world.
2) Perception is Based on Many Inputs, Some from the Outside World, Many if Not More are Internal
In order to figure out what is going on outside the locked bony skull, it turns out that our brain relies on more than just the electrical impulses that are indirectly related to the outside world. Our brains also rely on electrical signals generated internally, like thoughts, past experiences, etc.
For our patients, this can be a very challenging, and sometimes threatening concept. Moseley also addressed this challenge by using visual illusion as a demonstration.
Seth did this as well and even used the exact same visual illusion, but he took it one step further with what I found to be a brilliant and compelling audio example. Listen to the clip below, which I pulled from the presentation.
Here’s Seth’s interpretation.
“OK, so what's going on here? The remarkable thing is the sensory information coming into the brain hasn't changed at all. All that's changed is your brain's best guess of the causes of that sensory information.
Instead of perception depending largely on signals coming into the brain from the outside world, it depends as much, if not more, on perceptual predictions flowing in the opposite direction.”
Once you hear the meaning of the audio change without any change in the signal it gets very hard to deny that perception is significantly molded by internal factors.
The funny thing to me is that once I got the extra cue, it was impossible for me to perceive that same sensory information the way that I did the first time around. It’s not dissimilar from trying to unsee a visual illusion. Perhaps this is one of the reasons why improving persistent pain is so challenging. Once you hear the cue, it is very difficult to “un-hear” it.
3) Perception isn’t Passively Experienced, but Actively Created
If you accept that perception is based on a best guess and that it is based on many inputs, then it is hard to disagree with this last point, which is essentially Seth’s thesis of the whole talk. In his words...
“We don't just passively perceive the world, we actively generate it. The world we experience comes as much, if not more, from the inside out as from the outside in.”
To me, this statement is very closely related to the fundamental goal of Explaining Pain, which is to “...shift one’s conceptualization of pain from that of a marker of tissue damage or disease to that of a marker of the perceived need to protect the body tissue.”
To that end, I have been including the video as supporting material in my Explain Pain curriculum and have found it useful as a way to reinforce or even lay the foundation for concepts like neurotags, the orchestra in the brain, how heavily pain relies on context, and linear versus emergent thinking.
Sum Up
Pain is a conscious experience and therefore if you want to understand pain, you need to know a thing or two (or three!) about consciousness and perception. Anil Seth’s TED talk covers a lot of ground for being only 17 minutes long. Do yourself a favor and go watch the whole thing. I’ve only scratched the surface of it here, and there is a lot more including the rubber hand illusion, interoception and using virtual reality to simulate hallucinatory experiences.
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