Can one have pain and not know it?

By Flavia Di Pietro

I think about this a lot.  It leads me to ponder the distinction between pain and nociception.  We found a chapter on exactly this in a great book we are slowly reviewing at BiM – The Science of Pain.  The chapter’s title grabbed me: Conciousness and Pain.  It’s really got me thinking about both, and in particular that the latter can’t happen without the former.  If you were struggling to explain to someone the difference between pain and nociception, perhaps an easy way of doing so might be to point out that nociception may occur when someone is unconscious, whereas pain by definition cannot [1].

A nociceptive, tissue-threatening stimulus evokes adaptive behavioural responses which aren’t necessarily intentional or reasoned, called nocifensive responses. They are to minimise or escape from noxious stimulilike the flexor withdrawal response (muscle groups in the leg automatically bending the hip, knee and ankle after stepping on a spiky something).  We don’t need to be conscious for nociception to occur.

Pain however is an experience of the conscious brain, a sensory and emotional percept.  The most potent way we have of suppressing someone’s pain is through general anaesthetic, a process which globally eliminates sensory experience.  It’s possible that even in an unconscious, ‘pain-free’ state that nocifensive responses, like changes in cardiovascular rhythm, persist.

So the key ingredient for pain is the conscious brain.  Pain= nociception + consciousness.  That’s enough maths. Let’s talk about consciousness.  We don’t really understand how it happens.  There can’t be anything supernatural about it—there has to be an underlying neural activity and circuitry which, albeit complex, accounts for the emergence of conscious experience and willed activity [2], but we just can’t seem to quantify it.

We can use what we know about pain to learn more about the neurobiology of consciousness.  Pain is likely to tell us more about consciousness than other systems will.  Why?  Firstly, there is a highly variable relationship between stimulus and percept in the pain system.  In the absence of anything wrong with the visual system itself, light of a certain wavelength evokes the colour blue.  But a stubbed toe hurts more for some people than it does for others.  Secondly, emotion and affect play such a key role in pain as compared with other systems.  Happy or sad, I’ll see the colour blue (no pun intended).  My stubbed toe however may not bother me if I happen to be running away from something scary as I stub it.

Since I can’t help myself, let’s talk about this from a neuroimaging perspective.  Pain is subjective, and it cannot be ‘seen’ by anyone other than the person experiencing it.  Even with neuroimaging we cannot assess it objectively.  Imaging experiments tell us that there is a pattern, albeit variable, of spots in the brain that are active when someone is in pain.  But no image can tell us that the pain experienced is rated by that brain as a 5 out of 10 pain, around L4/5, and can escalate to 9 out of 10 when the mother-in-law comes to stay.  The ‘pain neuromatrix’ is too widely distributed for that, and there’s immeasurable capacity for functional reorganisation and redundancy in the system.

For the time being there are limits to the extent that we can ‘measure’ pain, and say with confidence that we fully understand pain.  Perhaps the neurobiology of consciousness is a good start?

About Flavia

Flavia Di PietroFlavia Di Pietro is a PhD student in the Moseley Group investigating the development of Complex Regional Pain Syndrome (CRPS) after wrist fracture. Flavia’s PhD focuses on the early detection of brain changes in CRPS using fMRI.  But get this – Flavia did Physiotherapy Honours degree at Notre Dame and completely cleaned up – Brian Edwards Memorial Award, Physio Research Foundation Award, Dean’s Award. Now, these things mean that she is not only ticking the academic boxes but all the other fluffy stuff too. No surprises that the NHMRC of Australia jumped to support her PhD.  So she has come over from Perth where she has been working as a physiotherapist.  All her achievements, however, pale in comparison to her celebrated status as the best Shoe Salesperson south of Milano, as evidenced by her taking out the 2006 and 2008 Diana Ferrari Golden Boot Award.  Clearly, she did not write this bio.

* One of the awards in Flavia’s bio is fictitious.

References [1] Merksey, H. (1986). Pain terms: a current list with definitions and notes on usage. Pain Suppl. 3 S215-S221

[2] Chalmers, D. (1995). Facing up to the problem of consciousness. J. Consciousness Studies, 2, 200-219.


  1. interesting discussion, m a bit interested to know if unconscious people do feel pain. thnx

  2. Hello Flavia,
    Very interesting article. I was pondering the same thing when I stumbled on it. Specifically, I am thinking about the idea of pain in virtual lifeforms. I think it would be a huge stretch to say that any modern computer programs are capable of simulating pain. We have characters in computer games which can “express” pain, or even react to or learn from harmful stimuli. To use the same vocabulary from your article, these virtual lifeforms can sense noriceptive stimuli, and can produce noriceptive responses, and can maybe do a little more processing for the long-term, but we would not say that these lifeforms are perceiving pain. Now my question is, at what point would you consider a virtual lifeform to be experiencing pain? How complex a circuit would it need? Let’s say it knows that it is in danger, and it knows the source of the danger, and it’s shaking in fear, and begging you for its life, or the lives of its companions, and all these behaviours are produced by its neural circuitry, and not pre-recorded or animated in any way… Would that be enough?

  3. Alberto Esteves Gemal says:

    Dear Flavia, I am an Associate Professor of Anesthesia in the Universidade Federal Fluminense and I have great interest in the subject you wrote in your blog. Did you write more on this subject? Consciousness and Pain? I have a different vision on anesthesia and am writting about this concept of mine. I found your proposal challenging and would like to know more about it. Thanks a lot.

    Flavia Reply:

    Thank you Alberto for your interest. I agree that this is a very challenging question. I would be be very interested to hear more about your vision of anaesthesia, since I feel that I almost ‘stumbled’ upon consciousness in my quest to define the difference between pain and nociception!

  4. Mehwish yaqoob says:

    hello flavia!

    you did explain the pain in concious and unconcious terms….
    But i would like to share my experience and will request you to help to think again where pain comes from?
    “during dreaming i saw i was in great aggression, was distroying almost everything which was in my dream…durind all that my ankle got injured..” i woke up and felt pinching pain in ankle immediately i woke up
    now question is thatwhere that pain comes from? as we know pain receptor require some stimulus from external physical world not through the world of images… to how extend i can apply
    pain =nociception+attention-to- concious?
    or a new combination is require???
    please solve it.

    Noel Reply:

    If I may try to add some insight. Have you experienced an ankle injury? If so, your dream may have “awakened” a neural tag/signature for this experience. If not, can it be possible your ankle “pain” in your dream is a construct/perception of what you believe an injured ankle might “feel” like? Just a thought.
    Be Stillness

    Mehwish yaqoob Reply:

    Hello Neol

    I reported that i felt pain, it was actually for a long term just like an ordinary pain after injury….

    If we consider that it was a construct of my dream than
    what does it mean??
    do dream can alter our biological response??? though they are just images and dont have physical basis???? or i should get the meaning that those images my mind had may evoke my neural connections related to pain??? then it means all the type of dreams we watch might have possibility/potential to evoke neural responses/ewperiences related to their contents and are still far away from my/our conciousness…..????
    I thought it requires long term explanations and research….

    Noel Reply:

    Peace Mehwish,
    May I suggest the following website to maybe introduce you to the realm of causal body and subtle body. The Integral Institute is a great place to start in regard to you current questions. Dream interpretation in my experience is one in which what is not dealt with consciously will be dealt with in the dream realm/subconscious realm. If you are interested I can provide you with a credible dream book although it is recommended to speak with a person that has experience in dream interpretation. It really is a science of its own, kind of like psychotherapy.

  5. ian stevens says:

    Gerald Edelman’s interview (highlighted by Barett Dorko) here may be helpful in some ways to this discussion?
    Both of these ‘verbs’ , pain and consciousness seem to require both scientific and philosophical consideration. It is heartening for me to hear the eloquence of Edelman describing the structure of the brain and the process of interacting/living. It was also fascinating to hear the importance of proprioception and embodiment.
    The brain seems to thrive on ambiguity, creativity and Edelman describes the practical formation of an intellectual monastery ,free of beauracracy for his scientists to create novel solutions.
    Is this not a metaphor for ‘unlearning’ in chronic pain –decoupling constraining defensive behaviour by embracing novelty and creativity?
    The discussion of the brain ‘seeking meaning’ through values embraced by the culture an individual lives in may be relevant to discussions of pain and the ‘techniques’ technologies that medicine uses in some circumstances to reduce suffering. I am thinking of Moreman’s meaning response(available and discussed before on this site) and how the environmental cues and physical symbols used in medicine/therapy sometimes alter brain activity and other measurable physical outcomes.
    Apolgies if this doesn’t add to a discussion ….
    Yes, there are some very intelligent people who think that consciousness is beyond material science to make sense of, including the brilliant polymath Ray Tallis and Alva Noe the philosopher. Any discussion in this area is bound to end up in confusion however.

    Flavia Di Pietro Reply:

    Hi Ian

    Thanks, firstly, for the link to the Gerald Edelman interview. No need to apologise, you have definitely added to the discussion. As a couple of us have pointed out in one way or another, Edelman states that understanding consciousness may heal the rift between sciences and humanities..

    I would like to hear a bit more about the metaphor you mention, Tim, regarding “‘unlearning’ in chronic pain'” and the brain’s thriving on ambiguity. I’m interested to know more, because I really enjoyed Edelman’s neuro-Darwinism theory: that the brain is not like a computer (I agree this an inadequate analogy), that we can apply the principles of evolution by natural selection to the brain and its development. Is this the theory you were drawing upon?

    Higher order consciousness, according to Edelman, is the ability to be conscious of being conscious. What do people think of this? And how does this fit in with the consciousness versus awareness stuff? Is higher-order consciousness another way of saying awareness??

    Noel Flores Reply:

    Your question on consciousness vs. awareness is a tuff one. The best that I can offer would be to learn what Ken Wilbur teaches on Integral Theory and levels of consciousness. I became interested in modern pain science etc. thru studying the mystics from different “religious” traditions, i.e. Buddism, Vedic, Christian mysticism, and their contribution to the experience of pain and suffering, i.e. the human condition. In my experience as a physical therapist we suffer more than we are in “pain.” Everything belongs.
    Be Stillness,

  6. Flavia Di Pietro says:

    Hi Simon

    Your project sounds great, any interesting findings so far?

    Regarding the definitions, I agree with you in that some concepts might only be possible to define with further argument and research. But I was just getting the impression that some people were talking about attention to pain and some about consciousness. I think perhaps the title I gave this piece was inappropriate wasn’t it? Because it would be tempting to answer ‘yes’ if one has suffered pain on and off for such a long time that it is perceived as generally constant.

    Looking back at my own text I didn’t really express myself well at all. Thanks for pulling me up on it. Yes it is our brain which “thinks, feels and decides” and it seems (thus far, anyway) to be superior to the brain of any other being. I agree with your paragraph on pain and its construction in the brain. My badly-expressed point was that we are still yet to quantify, or determine the formula for what makes us conscious (or aware?); ie, which bits of the brain have to be firing at a sort of baseline to keep us not just alive but thinking and feeling? And there may well be some people who think we might just never conquer this for whatever reason. What do you think?

    Simon van Rysewyk Reply:

    Hi Flavia,

    Thanks for the feedback about my PhD. Once the pilots have been written up, I’ll let you know what we found.

    Flavia: ‘I think perhaps the title I gave this piece was inappropriate wasn’t it?’

    The topic is great, but the discussion evolved along different lines. Maybe we can return to this important question later?

    Flavia: ‘…we are still yet to quantify, or determine the formula for what makes us conscious (or aware?); ie, which bits of the brain have to be firing at a sort of baseline to keep us not just alive but thinking and feeling? And there may well be some people who think we might just never conquer this for whatever reason. What do you think?’

    I am familiar with some of the objections to a neurobiological theory of pain or consciousness (e.g., the problem of qualia; or, the problem why pain state Y = brain state X, rather than brain state Z), but I am not convinced they have much merit. Given the current state of neuroscience, it is very hard to predict what the explanation of conscious phenomena (e.g., chronic pain) will look like. But, so what? I think it is always very hard to predict the course of a science, and especially hard to predict what an immature science like neuroscience will look like when it matures.

    The difficulty or mysteriousness of conscious phenomena like chronic pain is not a fact about pain – it is a fact about us! It is a fact about where we are in current neuroscience. It is not a property of the problem of pain itself.What do you think?

    Thanks! Simon

    Flavia Di Pietro Reply:

    Hey Simon
    I agree that we have so far to go before we can understand pain, or consciousness for that matter. I don’t know if this is because of intrinsic complexity or if it is our ‘problem’, ie the problem, or the neurobiological correlate of pain, has a solution we’ve just not found/quantified yet. I tend to go with the latter. I like to think that, while there may not be a ‘solution’ or a way we might ‘see’ someone’s pain, there is so much scope for understanding pain. We’ve so far to go with neuroimaging for instance…

  7. Simon van Rysewyk says:

    Tim writes: ‘we don’t ‘see’ the world as it is – we ‘see’ the world as our nervous system translates and transforms the incoming information’.

    Tim implies that the brain constructs subjective experience from sensory input, memory, and expectations based on environmental context. This is in contrast to the assumption that the brain maintains an accurate representation of the world based on incoming sensory infromation.

    Viewing pain as a bodily construction may help to clarify the nature of some chronic pain problems. Here are some exmaples:

    – Phantom limb pain. Ramachandran’s use of the virtual reality box on patients with a painful, clenched phantom hand are able to feel what seems to be kinesthetic feedback and are able to open the clenched phantom hand, thus relieving the pain. This may show that, in certain cases, it is possible to re-establish the construction of a particular aspect of frozen bodily awareness, in this case both the position and the pain of a phantom hand. This implies that facilitating/altering construction may be a viable approach to chronic pain managment.

    – Chronic pain. If pain is the product of construction, then pain may become chronic if the mechanisms of construction become self-sustaining and independent of sensory input eg., the perseveration of pelvic pain following surgical removal of the offending organs (Baskin & Tonagho, 1992).



  8. Tim Cocks says:

    I do love this blog and the interesting discussions that it generates.

    One of key principles/ideas that has stuck with me from Explain Pain training with David Butler, and David’s and Lorimer’s excellent audio version of the book is that “nociception is neither sufficient nor required for pain to occur”.

    With nociception out of the way, the equation could be simplified to:

    Consciousness = Pain!!!! To live is to hurt?? I hurt therefore I am???

    I think it fascinating that you raise the notion of consciousness in the pain discussion Flavia. Consciousness and attention are central in the study of hypnosis/trance states, which as the first poster mentioned, are powerful tools in the decrease or elimination of pain.

    I would, however, argue with the idea that “happy or sad we see the colour blue”, colour is another construct of the human mind, as is vision really – we don’t ‘see’ the world – a visual construct is created in the mind via the interplay between electro-magnetic radiation and the transforms that occur in our nervous system (which have yet to be adequately mapped) – we don’t ‘see’ the world as it is – we ‘see’ the world as our nervous system translates and transforms the incoming information.

    Back to the colour thing, there is evidence that our perception of the world can be altered by our emotions (see “Kicking to bigger uprights: Field goal kicking performance influences perceived size,” Perception, 2009, Vol 38: 1328-1340. as one example)

    A recent, absolutely brilliant BBC doco called “Is seeing believing” explores vision further through illusion (The McGurk Effect {yes thats real} will blow your mind!!!)

    The point of all this (i think i have a point??) is that perhaps the idea of there being a difference between a percept and a sense is not all that accurate – our ‘senses’ may well all be percepts in that we see, hear, feel, smell and taste what we think (first) will be there – an output from our complex minds, as opposed to sensory ‘input’.

    Korzybski said this so eloquently back in the 1930’s with his famous “the map is not the territory”

    Gregory Bateson, the English anthropologist, social scientist, linguist, visual anthropologist, semiotician and cyberneticist developed his “Criteria for Mind”, of which the most fascinating notion to me is that “news of difference” is the smallest component of ‘mind’, with ‘news of difference’ triggering the interaction between the various parts, the aggregate of which form the ‘mind’.

    More and more I’ve been coming to think of nociception as just another form of “news of difference” that our mind, via the neuromatrix (which fits with Bateson’s ‘aggregate of parts’, criteria for mind!!) may or may not transform into an output of pain, depending on the situation, circumstances, past experience, emotional state etc etc.

    Applying the ‘map/territory’ distinction to nociception, is it possible to consider that the two have been confused already in the concept of ‘nociception’ being the sense of threat (potential or real) to our tissues/selves. From a higher order/logical levels perspective, is it possible that nociception is not inherent, that some judgement (activation of mind) must take place already before a particular piece of “news of difference” is perceived as a threat.

    The argument that flexor withdrawl will occur to a ‘noxious’ stimulant (hence arguing for the existence of inherently noxious stimuli) does not hold if Bateson’s criteria are applied (the brain is only one of the aggregated parts in this) as the activation of mind is still held to have occurred to the ‘news of difference’ at a different level of the nervous system (one of the aggregate parts of mind)

    What I am trying to get at (poorly – I’ll save other posters the effort of pointing this out!), is the notion of a rethink of nociception, along the line of the rethink of pain. By calling any input ‘noxious’, a judgement is already being applied to this piece of news about difference – thereby already increasing its threat value.

    Just as we don’t have ‘pain receptors’, perhaps the notion of nociceptors imparts a judgement on the news of difference too early (that judgement being threat) – I’ll await the inevitable anatomical/physiological argument (I’m sure quite valid).

    Anyway, enough for now. Still is fascinating for me to see a convergence of some of the “hard” science of neuro-anatomy (should’ve paid more attentions at Uni!!), -physiology, -science, etc etc, fMRI and other brain studies and some of the more philosophical pursuits of understanding consciousness and the mind.

    Just as in physics, where the field became more philosophical when they could not break the atom down into any smaller parts beyond the electron, neutron and proton (we think there are qurks, up, don left and right) and we believe we can find the Higgs Boson if we can smash particles into each other at high enough speeds), the study of the brain might go through a similar transform when the elusive notions of ‘mind’, consciousness and attention can’t be found under more and more powerful scanning technologies.

    Maybe we will see a new LHC – not the Large Hadron Collider – a Large Human Collider – surely we could discover something if we accelerated streams of humans to near the speed of light and then ‘collided’ them????? I can already see a great comedy skit for this…….

    Flavia Di Pietro Reply:

    Hi Tim
    I like that you’ve brought up how we ‘see’ the world. Really good point. I had a look at the goal-kicking article too, interesting stuff!
    I agree with you in so far as we only see our own version of the world and that the ‘world’ may be completely different from the point of view, and the central nervous system, of the person next to us. I like the map/territory distinction.
    I would argue that yes, our perception of the colour blue (let’s stick with the colour example) is our own construct, and something that will differ from person to person. However, I would say that colour is not a “construct of the human mind” as you argue. The author of the article I wrote about states that “photons of 450nm invariably evoke blue”, and I agree. If someone saw a blue ball and called it anything but blue we would presume that they were colour-blind or that they had some kind of pathology in their visual system/central nervous system.
    Pain I think is quite different. We cannot measure it objectively and we cannot know for sure when someone is in pain. Yet we can accurately quantify the force or the heat of a noxious or tissue-damaging stimulus we might use to try and elicit pain. The point I’m trying to get to is that when we talk about the pain system there is a variable relation between the stimulus and the percept that results.

    Tim Reply:

    Hi Flavia

    First up, you mention in one of your replies that you may have worded this topic inappropriately; i think you’ve worded it brilliantly – the evidence is in the number of replies and the robust discussion thus generated!

    On colour, I would still argue that the notion of “colour” is a construct of the mind. As far as we are able to know with our limited neurologies, their exists in nature a spectrum of electromagnetic radiation, a very small portion of which we are able to “see”. Colour is therefore a product of the transforms (of which we have not mapped) that occur when certain wavelengths of this spectrum fall on the cones in our retina. In this sense, “blue” does not exist in nature, only in our minds as a representation (re presentation) of the wavelength.

    I know this is really quite terribly semantic in many ways, but these semantic matters do interest me, as do other epistemological questions.

    There really is some mind blowing examples of illusions in the doc I mentioned (Is Seeing Believing), some of which directly relate to colour – even when you know how they work the mind is still fooled into “seeing” different colours (check this website for examples

    Beau Lotto is one very clever scientist!!

    The rubiks cube (my name for it) illusion with the multi-coloured squares on a cube is a good demonstration of how the same wavelength can be perceived as different “colours” depending on the surrounding colours. And this one is all about Blue!!!! (

    I would absolutely agree that pain is very different, as it does not have a correlating physical phenomenon in ‘nature’.

    On the point of the relation between the stimulus and the percept that results when it comes to pain, i would argue even further that there is NO relation between the stimulus and the output of pain, in the sense that no equation could adequately explain to what levels pain is experienced, or even if it is experienced at all, for any given stimulus.

    Flavia, please don’t take this as in any way criticism of your article or work, i just love discussing (arguing!!) this stuff.

    I find it so fascinating that the study of the human experience from the perspective of neurology ie the “brain” is converging with the study of the human experience from a more philosophical “mind” perspective in many exciting ways, and the opportunity for learnings and robust debates are unlimited!

    A big thanks for hanging about and reading the comments and responding – even to rambling hacks like me.



    Flavia Di Pietro Reply:

    Hi Tim
    I can definitely see where you’re going with the colour argument. I’m going to check out the Beau Lotto link…

    I understand your point: “In this sense, “blue” does not exist in nature, only in our minds as a representation (re presentation) of the wavelength”.

    Whether colour is constructed in the human mind or is a physical entity in itself, the fact remains that there is general consensus as to what blue looks like. But with pain, as you’ve said so well, there is not that clear relationship between stimulus and percept.

    For this reason (and lots more that people might suggest?!) the visual system, in comparison with the pain system, isn’t an interesting entrypoint into the neurobiology of consciousness, because it doesn’t provide us with that highly variable and therefore intriguing stimulus-response relationship that pain does. Delving into someone’s colour ‘blindness’ may only take us through the visual system itself and the visual cortex for instance, while the brain’s role in the production of pain is so complex..

    I agree with you-it’s exciting to have philosophy and neuroscience in the same chat!!
    And, no worries, I’m enjoying the discussion!

  9. Simon van Rysewyk says:

    Hi Flavia and BIM,

    I am a PhD student (psychology, University of Tasmania) using TMS to investigate whether facial expression is a mechanism of pain empathy. I would like to contribute some thoughts to your post and to some of the replies. Thanks!

    Graeme states that a consciousness studies perspective on pain is largely ornamental and of little use. Yet, if fundamental questions are excluded, learning to ask a better class of question becomes much more difficult. Questioning is part and parcel of research and scholarship. Philosophical questions about pain may highlight new ways of thinking about clinical pain phenomena and pain control. Keep in mind that the sensory theory of pain instantiated in Western culture by Descartes (1649) that has so profoundly affected our view of pain (and human nature and language) is essentially a philosophical theory. A consciousness studies perspective aligned with pain neurobiology may help to free us of classic Cartesian assumptions about pain. But, we’ll never find the way forward if we don’t place our question marks down deep enough.

    Flavia’s post on the distinction between nociception and pain reflects the vast body of literature which demonstrates that pain is not a simple sense modality involving the transmission of specific messages to specific brain areas. When patients are in pain, the brain is engaging in massive processing that engages structures that contribute to emotion, sensation, and cognition.

    It is now clear that nociceptive signals do not simply make their way through the neruaxis and then enter consciousness, as Descartes thought. Instead, such signals have multiple neural destinations. They trigger intricate, top-down processes that create the conditions required for the emergence of pain as a part of the dynamic pattern of conscious awareness. Pain is a feature of bodily awareness that is dependent on certain conditions, normally tissue damage. Plausibly, bodily awareness, like other aspects of consciousness, is an emergent consequence of brain activity.

    In an intact nervious system and under normal conditions, nociception is required for acute pain but not sufficient to explain patient presentation. As Flavia makes clear, the individual in whom nociception is happening must be conscious and must not have his or her consciousness fully engaged in another task if pain is to emerge in consciousness. As I am sure the BIM people can appreciate, individuals differ greatly in pain intensity to a common injurious event because each constructs a unique reality and bodily awareness. If this is correct, clinicians need to appreciate that, in humans, pain is always more complex than nociception because several factors contribute to it. This may provide a rationale for the development and refinement of new psychological interventions for pain.

    Consider the effects of psychological interventions such as hypnosis and distraction on pain, as discussed by Graeme. These interventions may address the complexity of human perceptual experience and the psychological uniqueness of the individual. It is thought that effective hypnotic suggestion directed at removing pain changes the construction of the pain experience. If so, then the processes of construction are possible targets for pain intervention as the neural regions and synapses that subserve nociception.

    If anyone is interested, we can discuss in detail the putative mechanisms of pain as the end product of construction of bodily awareness?

    Many thanks,

    Descartes, R. The passions of the soul. In: Haldane ES, Ross GTR (trans), The Philosophical Works of Descartes, V. 1. New York: Dover Press, 1649/1967: 219-327.

    Graeme Campbell Reply:

    Re: “Graeme states that a consciousness studies perspective on pain is largely ornamental and of little use”. I protest – I’ve been taken out of context!! I’ve a good mind to skitch Tony Abbot on to you !! He he he.

    Actually Simon, I agree with you (I think) that consciousness studies may well be fruitful and help develop new paradigms and strategies. Without wanting to sound too precious about it all though, I wonder if looking to reduce human consciousness to neural circuits etc is actually beyond science although I’m not necessarily saying anyone here is saying that BTW. Anyway, I’m not up for a metaphysical or semantic debate althoughI suspect is where all this leads us.

    Moving right along, are you familiar with anecdotes of chronic pain sufferers who develop amnesia who are henceforth free of their pain (or something like that). Reformatting the not so hard drive as it were. Interesting don’t you think?

    And poor old Descartes. At least he was an excellent artist even if that’s only my brains construction of what I think I preceive. See!

    Flavia Di Pietro Reply:

    You’ve both kicked off a good discussion here.
    Before anyone gets remotely close to a conclusion (as you say so well Simon, research is all about questioning over and over again), we’d all need to be on the same page with regard to definitions of—and differences between—consciousness, awareness and attention. BUT it’s a bit of a circular argument; these need definition before further discussion and yet the only way to define them is to discuss them!
    Regarding consciousness, some folks (including, I gather, the authors of the article upon which I wrote my original post) think it can and will eventually be quantified, that is a neurobiological correlate of human consciousness will be ‘discovered’. On the other hand some people feel that there is something that just makes us human and superior beings to other animals—a soul or a spirit perhaps? I don’t see this argument being won by either party any time soon. And I’m with you, Graeme–I don’t have the energy to go down that road right now!
    On another note, I’m interested in your project, Simon. Would you mind giving us a bit more of a summary of what you’re investigating and how you’re investigating it?

    Simon van Rysewyk Reply:

    Hi Flavia,

    You write: ‘BUT it’s a bit of a circular argument; these need definition before further discussion and yet the only way to define them is to discuss them!’

    It is natural to think that we should precisely define our terms before we plunge ahead, building and tesing theories. Right? In science, theories about certain things and definitions as to what counts as those things evolve together, hand in hand. Precise definitions become available only fairly late in the game, as the science that embeds them firms up and matures.

    Concerning defining ‘consciousness’, we can use the same strategy as has been used in the early stages of any science: delineate the paradigm cases, and then try to bootstrap our way up from there. We can generate provisional agreement on what things count as unproblematic examples of consciousness, and then design interpretable experiments.

    For example, acute pain qualifies as a paradigmatic conscious state. Then, we can include in our list conscious pain states that are not usually considered sensory experiences per se such as chronic pain, affective or motivational aspects of pain, pain memory, perspective-taking during pain observation, and so on. More peripheral cases would include fetal pain, pain and sleep, pain and severe cognitive impairment, and the moral aspects of pain (guilt, shame, desert). These categories may be rearranged later under the pressure of new discoveries.

    Flavia: ‘Regarding consciousness, some folks (including, I gather, the authors of the article upon which I wrote my original post) think it can and will eventually be quantified, that is a neurobiological correlate of human consciousness will be ‘discovered’. On the other hand some people feel that there is something that just makes us human and superior beings to other animals—a soul or a spirit perhaps? I don’t see this argument being won by either party any time soon.’

    In fact, the ‘argument’ has already been won. The weight of neuroscientific evidence now implies that it is the brain, rather than some nonphysical soul, that feels, thinks, and decides. That means that there is no soul to experience pain. Certainly, we do still have pain, and pain is as real as it ever was. The difference is that now we understand that pain is an event happening in the physical brain. It means that there is no soul to spend its postmortem eternity blissful in Heaven or miserable in Hell. Stranger yet, it means that one’s own subjective awareness (of pain), is itself a brain dependent way of making sense of neural events. And, the brain’s knowledge that this is so is likewise brain-based.

    About my PhD. Thanks for asking!
    Theoretical target: pain facial expression functions to solicit observer approach behaviours and caregiving (e.g., Williams, 2002).
    Experimental focus: to investigate whether pain facial expression potentiates approach-motivated motor behaviours during pain observation.
    Pilot Tests: (1a) to compare reaction time to initiate approach and avoidance movements in response to pain versus neutral faces; (1b) to compare reaction time to initiate approach and avoidance movements to pain faces versus painful body parts, either viewed alone or together; (2) to compare (1a) and (1b) with observer corticospinal excitability (CSE); (3) to compare reaction time to pain faces and/or painful body parts primed with approach or withdrawal values with CSE.

    Any feedback greatly appreciated!


    Simon van Rysewyk Reply:

    Hi Graeme,

    Yikes! Tony Abbott! What have I unleashed?

    You write: ‘I wonder if looking to reduce human consciousness to neural circuits etc is actually beyond science…’

    I think the progress of science is impossible to predict with much accuracy. But, given the history of science, it is likely that we currently misconceive many problems about the brain/mind because we do not have the scientific understanding to create and make precise the relevant concepts. Consciousness may be a case in point, e.g., it sometimes seems obvious that consciousness is a unitary phenomenom: either you have it or you don’t (lke light, it is either off or on). But, this apparently obvious idea may turn out to be quite wrong. I think neuroscience is still wet behind the ears. We’ll just have to wait and see what happens!

    Graeme: ‘are you familiar with anecdotes of chronic pain sufferers who develop amnesia who are henceforth free of their pain (or something like that). Reformatting the not so hard drive as it were’.

    No, I haven’t heard of this. Interesting! It may turn out that ‘pain amnesia’ shares a common mechanism with hypnosis and pain distraction since effective hypnotic suggestion directed at removing pain alters the construction of the pain experience.


  10. Tara Packham says:

    Hi Flavia

    I wonder what Dr Paul Brand would add to this discussion – he was hitting some of these issues when he wrote his book “The GIft of Pain” back in the 1980s. He developed a unique perspective as an orthopedic surgeon working among leprosy patients in India … and of course, those poor folks lose their nocioception, which is what leads to the loss of digits that is associated with that disease. Brand passed away several years ago, but I recently re-read his book and was impressed that he was thinking about plasticity and pain long before it was in vogue.
    I am an OT working with CRPS clients and doing CRPS research, and I have seen folks with CRPS who do not complain of pain, but have all of the autonomic and trophic changes. My personal theory is that CRPS could perhaps be classified into subgroups not on the basis of whether or not there is an injury to a major nerve branch (the current type I and type II distinction) but rather on the basis of the primary symptom cluster: pain/sensory, autonomic, or movement/motor. I wonder if that might be a better way of approaching it, and lend more direction to how to treat these folks.

    Flavia Di Pietro Reply:

    Hey Tara
    Great input, thanks. I agree that there’s definitely scope for better diagnosis and subgrouping of CRPS. It’s interesting that both clinically and in research, the terms CRPS Type I and II are still in use, when the signs and symptoms vary greatly in both of these, irrespective of nerve damage.
    Diagnosis of CRPS is quite often dependent, as I’m sure you’re aware, on the presence/absence of pain and of numerous signs and symptoms in the vasomotor/motor/trophic/sensory/sudomotor/oedema domains. (Check out work done by the authors Harden or Bruehl–they’ve done lots on diagnostics and validation of diagnostics. A particularly interesting paper is by these two and a pile of other authors on the development of a continuous-type severity score in CRPS–as opposed to the existing dichotomous diagnosis).

  11. Graeme Campbell says:

    Hi Flavia

    You do interesting work but ask awkward questions.

    Can one have pain and not know it? I suspect addressing this question might all end in tears and semantics but I’ll give it a stab anyway.

    I’m too scared to go down the defining ‘consciousness’ road, but perhaps it might be fruitful to talk about what I hazard is a related concept, which is attention. We know if we put our attention on something other than the pain, the pain might go but the nociception is presumably still there – e.g. kid cuts knee & parent offers an ice cream -miracle!; doctor in white coat offers diagnosis far less fearful than patient first thought and pain settles etc, etc.

    In Darwinian terms it doesn’t make sense for us to pay attention to the nociception when a 250kg tiger is bearing down on us & we need to get to safety. Similarly we need to react to falling out of a tree so our balance reactions take precedence over nociception and we might not feel pain whilst responding to being off balance. (We might might feel pain soon afterwards though). Conversely, when the nociception is signalling life threatening conditions, if we can’t or don’t respond to it (as in the case of ‘congenital insensitivity to pain’ or asymbolia respectively) then we don’t get to pass our genes on so readily. Therefore from an evolutionary perspective it makes perfect sense to have a wide variation in our ability to respond to nociceptive input. Not so if we can perceive the colour blue in various ways. Anyway, God invented psychedilic drugs for that. But back to the story. In either scenario we have too much or too little attention to nociception – both with little or no survival utility. However, in either case I can forsee that the person is conscious and can have consciousness, be it with or without pain. Therefore I think the “formula” you offered of ‘Pain = nociception + consciousness’ would be more accurate if you substituted ‘attention to nociception’ for ‘consciousness’. However, I don’t think your formula is something you meant to be taken at face value and I would be interested on what other thoughts you have on this subject.

    Another point to ponder. Is it not true that yogis have inflicted pain upon themselves in the pursuit of higher consciousness (or is that attention?). Why?? Could it be that in overcoming the more trivial challenges to their attention and then the even more compelling things such as food, clothing and shelter, that in order to improve their attention, such persons need greater challenges to overcome ? What could be more attention grabbing than pain. Sleep perhaps?

    And back to the story again .. So can one have pain and not know it? By IASP definition you cannot. Even in the case of asymbolia, which is argued to challenge the IASP definition, there is not the emotional aspect & therefore it is not pain by IASP criteria, although it might not be strictly nociception either.

    Where’s a philospher when you need one?


    Flavia Di Pietro Reply:

    Hi there Graeme and Samantha
    Cheers for the questions and comments. I think you both could be onto something here: Graeme with the remodelled equation, “pain = nociception + attention-to-nociception”, and Samantha with a couple of your points. To elaborate…
    Graeme, I personally agree with your “Darwinian” way of looking at pain versus nociception, all ultimately with the aim of survival of the fittest. Distraction, whether it be in the form of a yummy ice-cream or a 250kg tiger, is a very powerful pain-blocker even in the presence of ongoing nociceptive input. Which leads me onto..
    ..Samantha and your, albeit rare, pain-free days. I think people who have/have had “pain issues” probably have a lot to offer to the table here. I gather from your comment that you might be able to switch off or stop thinking about pain? Perhaps you have figured out a way of ‘distracting’ yourself from it so that you can enjoy those pain-free days.
    I don’t know much about yogis unfortunately but I am certainly interested in learning more because that sounds fascinating. Pain is a powerful attention-grabber (in the absence of that tiger, or similar, which needs more attention); anyone who has had to guard their movement for example, as a result of pain, can likely appreciate the highly efficient protective nature of pain.
    I agree-we definitely need a philosopher here!

  12. Samantha Vimes says:

    It’s possible to have pain and not really be aware because one has ceased to think about it. I’ve had pain issues as long as I could remember, and only in my 20s did I realize that other people did NOT always hurt a little, all the time. Finally found out about fibromylagia and saw a doctor who verified.
    On the rare days I am pain-free, I wonder what’s *wrong* with me for a while, because I feel lightweight and almost giddy, but it takes a while to register it’s the absence of pain, because pain is simply what is normal for me.

  13. What happens with RSD/CRPS pain when the patient takes daily Ketamine capsules as part of pain management?

    Flavia Di Pietro Reply:

    Hi Judy
    Thanks for your input. None of us in this team are pharmacologists and as such I can’t really offer much here! To be quite honest I’m not sure of ketamine’s mechanism in pain relief. Like any drug I expect it provides pain relief for some people and not for others.
    Ketamine has a wide range of effects, depending on dosage too. I would recommend talking to a pharmacist or a pharmacologist if you are interested in this.

    Judy Reply:

    As I understand it, Ketamine is a disassociative drug, and it works by separating the brain’s perception and memory of pain from the cause of the pain, e.g. cutting into flesh during surgery etc. Through this disassociative mechanism, is reduces the pain felt by RSD/CRPS patients.
    As a recreational drug, it apparently makes users go wonkers in clubs.

  14. Is tooth abscess pain nociceptive? Treated this with mirror therapy and for 3 months pain kept disappearing only to return. I mistakenly thought it was CRPS (got crps post colles arist fracture 1998 and developed whole body symptoms – in remission now) so consequently lost the tooth.

    Is pain from cutting into flesh (minor surgery) nociceptive? Hypnosis stopped pain of mole removal surgery for the first half until I lost concentration. Interestingly local needles do not work for me.

    If these are nociceptive pain then it seems to me that it is possible to manipulate the perception of this type of pain as well as chronic pain.

    Flavia Di Pietro Reply:

    Hi there
    Thanks for your comments. Just to reiterate, nociceptors are ‘nerve-endings’ which fire in response to tissue-damaging, or potentially tissue-damaging, stimulus (eg a dental abscess as in your case, or for example a paper cut). Pain however is a percept, as opposed to a sensation, and is informed by so much more than just the nociceptive information coming in. A nociceptive stimulus may cause pain, it may not.
    So I would say firstly, that no, “tooth abscess pain” isn’t nociceptive necessarily..the abscess is itself a nociceptive stimulus, but the nociception may not result in pain.
    “Cutting into flesh” is nociceptive stimulus, and again may or may not cause pain. Think of a tiny injury like that paper cut which could potentially be very very painful. Then think of a big injury, a snapped tendon or a fractured bone, sustained while running away from something, in which case it is likely pain would not be felt at the time.
    As such, you are right it is possible to ”manipulate the perception” of pain, acute or chronic.
    You brought up some interesting points, and you can see why this is a really tough issue to get one’s head around. If only it were as simple as the visual/auditory system!!