Imagine if pain didn’t really bother you. It’s just data. A safety bulletin.
Quite a reach, isn’t it? Can you even call that “pain”?
What does it want?! Well, it wants to bite you. Duh.
The post is mostly about the phenomenon and implications of pain asymbolia, pain without emotion or meaning, like a robot would feel it: “Ouch, that is very painful. If I was human, this would be very emotional. I will now make a face to indicate that I am hurting. Ow. Ow. Ow.”
This is actually possible — though only with brain damage. I could do a whole ‘nother post on whether it is possible to get there psychologically, and perhaps I should. But the neurological phenomenon is fascinating and instructive. I will:
- tell the scary scrubber story
- dig into the science of pain asymbolia
- explain the example of the “brave mouse”
- speculate about the prevention of trauma
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The scary scrubber teaches me about the motivational power of pain
I was washing dishes with a copper scrubber, and a loose end of copper wire slid several millimetres into the flesh under a fingernail — a tiny freak accident. It felt like a deep bee sting.
The next day, I found myself weirdly unable to touch that scrubber! The scary scrubber had stung me, and using it with my bare hands felt as repellent as sticking my hand in a blender. Even though it was super unlikely that it would sting me like that ever again, I was extremely motivated not to touch it with my bare hands. And yet a similar scrubby, a steel one in better condition, didn’t trigger the same motivation — my brain, apparently, only perceived scruffy scrubbers as scary!
That’s the motivational power of pain on display — its significance to us, its implications for behaviour — and that’s what would have been missing if I’d had pain asymbolia. If only! I would have been aware of the sting, but the scrubber would not have intimidated me.
That is what pain asymbolia will do for you.
This is a much newer, nicer version of the scary scrubber that bit me. The one that bit me was past its best before date, a tangled mess, the wire fragmenting — which is why it had a sharp end to stab me with.
Pain asymbolia — emotionally neutral pain
Pain is both a sensory and an emotional experience. In general, the suffering is tightly welded to the sensation, so much so that they seem synonymous. To hurt is to dislike hurting. Mostly.1
That’s pain asymbolia — pain without meaning — and it’s actually a thing, caused by physical or pathological damage to specific brain structures.2 It’s considered rare, but it could be a spectrum condition, and how would you know if someone just had a bit of it? How would you even know if you were missing just a little of your pain’s meaning? You don’t know how much a pain is supposed to mean to you! And so “it is possible that pain asymbolia occurs more frequently than is currently assumed.”3
Interestingly, it’s also possible that pain isn’t the only thing that loses its emotional meaning; the casualness about pain might only be the most obvious effect of losing “a general capacity to care about their bodily integrity.”4
People with pain asymbolia know they are in pain, but they aren’t fussed about it. If it represents an obvious danger, they are aware of the danger “intellectually,” but they aren’t highly motivated to avoid it.
They are not, for instance, spooked by things that have hurt them in the past. Like dish scrubbers.
The brave mouse: the unpleasantness of pain relieved
Pain asymbolia was induced in mice in a 2019 experiment by “muting” a brain region.5 😮 Not only does this result stand out for its potential clinical implications, it’s also an important validation of the existence of the phenomenon of pain asymbolia, which has always been a bit of ghostly phenomenon, case studies as rare as Bigfoot sightings and almost as unclear.6
You can’t really see it in this photo, but this mouse is a serious badass. She just does not care about pain! Do not mess with her!
When I first came across this study, it seemed really “neat,” but also irrelevant to real patients — cool brain science that is years from helping real people (at best). Plus it’s a mouse study, and the leap from mice to humans is often a deal-breaker, although perhaps less so in this case.7 But after reading Todd Hargrove’s thoughts on it, I am more impressed and optimistic. It could still takes years, of course, but these BLA neurons may actually be Very Important. I’m with Todd; I think the study is:
“…an encouraging sign that reductionist and brain-centric techniques for understanding and controlling pain may be making progress. It’s a welcome change from the all-too common experience of reading papers where the main takeaway is something like ‘wow pain is so complex!’ or ‘we know even less than we thought we knew.’”
But even if it’s not “practical,” it is a vivid demonstration of the complexity of the experience of pain, and how it can — occasionally — be broken into its constituents like a beam of light passing through a prism. It teaches us something quite substantive about how pain works, what it is made of.
Preventing the trauma of chronic pain
If one stab under the fingernail can turn me into a person that simply cannot bring himself pick up a dish scrubber, imagine what serious chronic pain can do to a person’s personality. A continuous bombardment of a strong and extremely unpleasant motivation to avoid something they cannot avoid, or often even identify, sounds a lot like literal torture!
People are traumatized and transformed by pain. But that might not happen if the BLA was inhibited — a wild thought.
Induced pain asymbolia could be the best of both worlds: you can still be aware of critical safety information about the world around you, avoiding the disaster of being completely insensitive to pain. But you also avoid the emotional disaster of being traumatized by it!
Disclaimer: “To hurt is to dislike hurting” presumes a threatening context. Yet another weird thing about pain is that it is actually possible to be happy about it, which is also about the “emotional experience” of pain. If the emotional experience is positive, for whatever reason, then we can like the sensation. I can’t think of a reason. Nope. Drawing a blank here.
But note the obvious: there are definitely limits to how much and what sort of pain can be enjoyed. Kidney stones are *never sexy* — no matter how much you like to be dominated.
Grahek N. Feeling pain and being in pain. Cambridge, Massachusetts: MIT Press; 2007. p213
Pain asymbolia is a condition where pain doesn’t feel bad. When people with this condition sustain an injury, they accurately sense it, and will describe the associated feeling as “pain.” But the pain is not unpleasant, and they are not motivated to avoid it. In other words, they have pain that doesn’t hurt. How can that be? The answer seems to involve damage to certain parts of the brain associated with emotion.
Jahn M, Steinberg H. [Pain asymbolia-discovered around 1930 by Paul F. Schilder, almost forgotten today?]. Schmerz. 2020 Apr;34(2):172–180. PubMed #32100096 ❐ PainSci #51369 ❐ Translated from German:
The experience that people react very variably to comparable pain triggers — we have all done it before — is perhaps too carelessly attributed to individual physical, gender-related, psychological or cultural-religious factors. In principle, this is of course correct and important, since ancient times pain concepts and explanation models have been subject to constant change and the central nervous pain modulation, also in connection with the above-mentioned factors, has been researched for decades. But couldn't there be a "pain symbolist" behind one or the other patient with noticeably reduced pain sensitivity?
- Klein C. What Pain Asymbolia Really Shows. Mind. 2015;124(494):493––516.
- Corder G, Ahanonu B, Grewe BF, et al. An amygdalar neural ensemble that encodes the unpleasantness of pain. Science. 2019 01;363(6424):276–281. PubMed #30655440 ❐ PainSci #51987 ❐
Pain asymbolia is not such a “blobsquatch”† that there’s been serious doubt about its existence. But there are reasonable questions about how to explain the case reports we have. Jahn et al again:
The detailed, internet-based literature research in PubMed provides relatively few articles from the last few decades, which are often individual case reports, or are of a more philosophical nature. In fact, we dare say most readers of this article have never heard of pain asymbolia before. So was Schilder wrong and perhaps presented a heterogeneous patient clientele with very different causes of pain perception disorders? After all, there are many.
Indeed there are. But when you can demonstrate pain asymbolia by disabling neurons in the BLC, that’s a game changer.
† Blobsquatch — This term is a skeptical reference to the fact that the only Sasquatch anyone has ever photographed is just a blurry blob (same with all other popular cryptids, UFOs/UAPs, etc). The sarcastic point is that Sasquatch/Bigfoot must actually be a blurry blob!
- Mice can be excellent models for human physiology, but they are also infamously misleading. Hence the charming research expression: “mice lie and monkeys exaggerate.” But mice are better models for brain research than metabolic stuff, and in this case the BLC was targeted because we already knew something about its role in human pain, and pain system traits are generally “highly conserved” in the animal kingdom (that is, quite similar in many animals over very long periods of evolution, because they are hard to change without compromising fitness). But yeah… we still have to cross that mouse-human chasm before we break out the champagne.