An Embodied Predictive Processing Theory of Pain Experience, 2022, Kiverstein et al.

Chandelier

Chandelier

Senior Member (Voting Rights)
An Embodied Predictive Processing Theory of Pain Experience

Kiverstein, Julian; Kirchhoff, Michael D.; Thacker, Mick

Abstract
This paper aims to provide a theoretical framework for explaining the subjective character of pain experience in terms of what we will call ‘embodied predictive processing’.
The predictive processing (PP) theory is a family of views that take perception, action, emotion and cognition to all work together in the service of prediction error minimisation.

In this paper we propose an embodied perspective on the PP theory we call the ‘embodied predictive processing (EPP) theory.
The EPP theory proposes to explain pain in terms of processes distributed across the whole body.
The prediction error minimising system that generates pain experience comprises the immune system, the endocrine system, and the autonomic system in continuous causal interaction with pathways spread across the whole neural axis.
We will argue that these systems function in a coordinated and coherent manner as a single complex adaptive system to maintain homeostasis.
This system, which we refer to as the neural-endocrine-immune (NEI) system, maintains homeostasis through the process of prediction error minimisation.
We go on to propose a view of the NEI ensemble as a multiscale nesting of Markov blankets that integrates the smallest scale of the cell to the largest scale of the embodied person in pain.
We set out to show how the EPP theory can make sense of how pain experience could be neurobiologically constituted.
We take it to be a constraint on the adequacy of a scientific explanation of subjectivity of pain experience that it makes it intelligible how pain can simultaneously be a local sensing of the body, and, at the same time, a more global, all-encompassing attitude towards the environment.
Our aim in what follows is to show how the EPP theory can meet this constraint.

Web | DOI | PDF | Review of Philosophy and Psychology | Open Access
 
Julian Kiverstein is a philosopher. Nice guy. He was in Edinburgh a while back and I took over the Book Review editing at the Journal of Consciousness Studies from him about 15 years ago.

Embodiment is all the rage in philosophy of mind. Unfortunately, it is scientifically completely meaningless. It is invoked to solve a problem that does not exist but everyone thinks does.
 
Firstly, I remember we have discussed tgis paper before on here. I don't know if it had its own thread. It reminds me that all these citations from brain retraining enthusiasts track back to tiny cliques of academics who have buried themselves in little nonsense vortices because they don't have a wide angled view of their interests.
 
Utsikt said:
Can you elaborate?
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The idea is to try to explain how conscious experiences such as pain or images or melodies arise out of the 'systems' that people think organisms are. It harks back to the work of Francisco Varela and Evan Thompson who suggested that living systems are conscious because eo fthe way their dynamics are self-renewing.

The mistake is to assume that you have to invoke a 'system' in order to get over the locality problem - which is how a single experience can arise from biological events in a whole lot of different places at once, as in a network of neurons. The embodiment idea is often combined with an 'extended mind' idea that suggests that the system involves the environment as well as the body and that experience arises from the interaction between mind and environment. This again overlaps with the concept of 'enactive mind' - consciousness arising from interaction with world.

There is even a fourth E to add to embodied, extended, enactive so people talk of 4E theory. What they don't seem to realise is that if you extend the system to world then you no longer have any individual system that would explain individual experiences - just an interactive world. The whole thing becomes completely incoherent but nobody seems to mind.

Moreover, 'Embodiment' does not actually mean anything in physics. The physics does not change. And since physics is the study of cause, the causation does not change, so nothing can. be predicted from these 4E theories. They are dead.

The false assumption, of course, is that conscious experience must arise from a whole system of interacting parts. There is no way in physics, or even the more pervasive common sense conception of locality (what happens here and now, happens here and now, not there and then) for this to work. And there is no need because there are single events in brains rich enough to be conscious experiences - in individual neural sites.

The assumption is also based on the idea that experience belongs to a whole living organism unit and tries to explain it on the basis of the properties of 'life'. It is the modern version of 'vitalism' that early twentieth century science thought it had put to bed.
 
@Jonathan Edwards

Thank you!
Jonathan Edwards said:
There is even a fourth E to add to embodied, extended, enactive so people talk of 4E theory. What they don't seem to realise is that if you extend the system to world then you no longer have any individual system that would explain individual experiences - just an interactive world. The whole thing becomes completely incoherent but nobody seems to mind.
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That’s been my thought as well when people talk about systems. Where does it end, and why would it end there and not here?

This is probably related to the thing you discussed in your paper about how «the system» would know if something happened, because only the part it happened to actually knows something happened to it right then.

The only way around it would be to have some kind of observer that observes all of the states of all of the parts of the system at all times, and that observer is the «mind», but if the mind can react to and act upon the body, the physics doesn’t add up one bit.

It feels like someone trying to make an electrical circuit and want to make the circuit detect if the LED at the one end is turned on or off, and saying that they know by looking at it, so they’ve completed the task.
 
Jonathan Edwards said:
And there is no need because there are single events in brains rich enough to be conscious experiences - in individual neural sites.
Click to expand...
Like synapses or neurons or something more specific? Even those are sort of composite things made out of smaller parts, so how does this get around the issue of locality?

When I think about these things I start to feel like I'm probably looking for the wrong thing -- like my impression being conscious is kind of an illusion and the reality is something else. There's some sort of gap that seems impossible to get over between neurons firing and a 'thought', and I just stare at my mental model of the brain feeling like one of those animals that can't recognize their own reflection in the mirror.
 
ScoutB said:
Like synapses or neurons or something more specific? Even those are sort of composite things made out of smaller parts, so how does this get around the issue of locality?
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They way I’ve understood the argument is that neurons can receive tens of thousands of inputs, and that that’s enough complexity.

Whatever goes on inside it isn’t known, we just know the outer bounds of the space where the experiencing must be - i.e. a neuron.
ScoutB said:
When I think about these things I start to feel like I'm probably looking for the wrong thing -- like my impression being conscious is kind of an illusion and the reality is something else. There's some sort of gap that seems impossible to get over between neurons firing and a 'thought', and I just stare at my mental model of the brain feeling like one of those animals that can't recognize their own reflection in the mirror.
Click to expand...
If JE is right, the single «me» is an illusion, because there are multiple neurons that experience. But who (or what) is experiencing the illusion?
 
ScoutB said:
Like synapses or neurons or something more specific? Even those are sort of composite things made out of smaller parts, so how does this get around the issue of locality?
Click to expand...

This is exactly the point William James (the father of psychology and brother of Henry the novelist) made in 1890. At the time it was almost legitimate and would certainly have seemed so. But since the development of generalised quantum field theory in the 1980s we have finally reached a physics that, as Leibniz predicted, makes individuals single events or actions - quanta of action in fact. Moreover, it allows for those events to have domains of any size.

A photon that comes from another galaxy to a telescope on earth is not a tiny billiard ball. It is an action that has a domain of cubic light years. A sound wave reaching your ear from a trumpet is a single action. It is as real as a proton. The answer to James's objection is that we need to find a quantum of action that connects all the synaptic potentials in the dendritic tree of a neuron to the resulting spike current. There are actually quite a range of options that would do but nobody has yet pinned down which fits best.

Interestingly, although we were taught at school to think of everything being made of atomic parts, when I got to university and started studying biochemistry my tutor told me that physical chemistry doesn't work like that. chemistry is now quantum physics and that is actions. Moreover, when Hodgkin and Huxley worked out how action potentials propagate in the 1950s they could see dendritic integration as a single event using old fashioned Maxwellian electrodynamics, which has a lot more in common with quantum theory than people think.

So for Andrew Huxley there was no problem in seeing synaptic potential integration as a single event. I discussed this with him not long before he died, when he was still mentally as sharps a razor. More recently complexities have been identified and this is a simplified version of the sotry but I think it remains valid.
 
ScoutB said:
When I think about these things I start to feel like I'm probably looking for the wrong thing -- like my impression being conscious is kind of an illusion and the reality is something else.
Click to expand...

The philospher David Chalmers and others have made 'illusionism' trendy recently. But I am happy with the idea that the existence of experience cannot be an illusion since even an illusion has to be an experience for something. The illusion is that there is only one 'me' that is conscious. That almost certainly is an illusion. And William James could see that possibility too. He didn't miss much. He said the individual cell consciousness idea (polyzoism, which was quite popular in the nineteenth century) was the only one that was not contradictory. Yet even he bottled out. He said there must be a single soul, and then 400 pages later said that there isn't after all. His biggest cop out.
 
ScoutB said:
There's some sort of gap that seems impossible to get over between neurons firing and a 'thought',
Click to expand...

This is something we are taught by cultural norms. There is no gap. In the seventeenth century, before mechanistic physics became the new gospel, thinkers had no great issue over this. They tended to think of everything in the world as sentient. Leibniz even identified actions as the sentient units (he called them monads). In many ways modern science has made people much more blinkered than they were 400 years ago.

And of course it is not neurons firing. That is a mistake introduced by people like David Papineau and Francis Crick. The thought is a neuron receiving signals. It is an input of a story provided by other neurons that have worked out what is going on.
 
Jonathan Edwards said:
And of course it is not neurons firing. That is a mistake introduced by people like David Papineau and Francis Crick. The thought is a neuron receiving signals. It is an input of a story provided by other neurons that have worked out what is going on.
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I think this just unlock a new understanding for me.

When you’re saying that anything can experience, that just means that something can happen to anything, right? To experience is to have something happen to you.

But what about the random quantum events like radioactive decay? That’s presumably not triggered by something else happening to whatever the first step of the decay is, so can experience also be that a change occurs, either caused by something internal or external to the experiencer?
 
I took electromagnatism and QM many years ago. The thing you're calling 'action', when you say a photon is an action, maps to the wave function of a particle or system. Technically, the wave function describes an isolated system. If the neuron we're talking about is the only thing in the universe, it would have a wave function describing its (probably rather boring) state/behaviour. I would think to accurately describe the behaviour/experience of a neuron that's sitting amid all your other neurons the wave function would have to be of the whole system. But maybe something about the structure of neurons and their synaptic clefts makes them almost like truly isolated systems?

Jonathan Edwards said:
But I am happy with the idea that the existence of experience cannot be an illusion since even an illusion has to be an experience for something. The illusion is that there is only one 'me' that is conscious. That almost certainly is an illusion.
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Yeah, I don't know about Chalmers, but don't think I meant whatever he did by illusion. I don't mean nothing. Just that the reality seems to be something that doesn't fit with what I'm expecting. I keep catching myself looking for a single master 'observer' in the brain, which is punting the problem of consciousness. Your 'one me' illusion is closer to what I meant.

Jonathan Edwards said:
This is something we are taught by cultural norms. There is no gap.
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Maybe! I don't think I exclusively meant the gap you're thinking of though. Any direction I try, there are big steps I feel I'm missing. The jump from 1 neuron being conscious, to my conscious experience, would be an example. To be clear I don't think there's *magic* in the gap, just that I don't understand it.

If we take a neuron and remove parts of it does it stop being conscious at some particular point?
 
Utsikt said:
When you’re saying that anything can experience, that just means that something can happen to anything, right? To experience is to have something happen to you.
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In the first layer analysis, exactly. The vernacular meaning of experience is to have something happen to you, or a tree or a rock. We say a tree experiences the full force of the gale. We can say that the rock experiences forces from a lightning discharge via both acoustic waves through ground (first) and then through air.

But in quantum theory the only truly individual dynamic unit that might experience is an action or indeed a happening or event. So how do we make sense of something happening to a happening? The answer is complicated but I think quite satisfying for something like a living cell.

To work it out we need to consider the causal story that underlies quantum theory. Quantum theory says that the universe consists of fields of potentials with a metric we call spacetime such that for any location in space and time dimensions there are field values. (For fields like the electron and quark fields things get much hairier but fortunately we are chiefly interested in the electromagnetic field whch has a classical spacetime format.) The theory then says that for any arrangement of potentials in a local domain there will be various predictable probabilities of certain happenings, in the form of quant of action, and that these quanta then determine field potentials in this or other spacetime domains at later time points, constrained by the speed of light. Quanta of action often appear to 'transport' some mass or energy to a new site but the theory prohibits any actual account of anything 'moving on a trajectory'.

In short quantum theory says:
Field potential pattern here > possible happenings > actual happening > new field potential pattern

If the experiencing unit is a happening then presumably what it experiences will be its causal input, which in this theory is a field potential pattern. That is neat because it means that every dynamic unit can be expected to experience a rich pattern which solves William James's basic problem.

The next question is what extent of spacetime domain will contribute to that pattern. Is it the whole universe of potentials that ever were and will be or just a local patch? The logical answer is that it is just the patch that contributes non-trivially to the probability of the happening. Quantum theory always has this infinite causal regress in spacetime built in to the equations but it sorts itself out because we are only dealing with probabilities, not certainties, and the influence of field values beyond a small domain usually drop off precipitously so the math works fine. (For galaxies spinning and the putative existence of dark matter there may be interesting caveats to that.)

Leibniz saw all of this and was able to see that for the dynamics of little lumps of stuff, which is what physics mostly wanted to explain, the spacetime domain of potentials that influences happenings within that little lump as a whole is likely to be the extent of the lump. The simple example is the peal of a bell. It is an action or happening that occurs within the whole bell and its nature is determined by the field of potentials that is the bell and nothing else much.

This allowed Leibniz to see a way to bring back a more intuitive sense of a 'thing' with dynamic identity. He saw that happenings within a cell would be determined by the field of potentials (possibilities) provided by the 'body' that is the cell alone. So any action within the cell would be informed almost exclusively by this body, although the body could itself be informed by, and represent, the wider universe. It was most likely to represent the wider universe if it was sitting inside a mass of other cells that signalled to each other inputs that signified outside events - a brain.

In this way we can be allowed to see experiences as belonging to the cell, at least vicariously, in that every action or happening that occurred in the cell domain would 'belong' to that cell domain.

Sylvia Paddock and Tom Buervenich wrote a little book called Plato's Prisoners that uses a slightly different metaphor which I like. They see experiences as the universe peeking in on its own fields from different domains, as if looking in from different Advent calendar windows. There is a counterintuitive reversal involved however you describe it, but I think this makes some sense.

In technical terms happenings that occur to 'body' domains as a whole are acoustic (like the bell). So it would make sense to suggest that the 'me's' that experience in cells are a series of acoustic actions tied together by the stable cell parameters. But there are all sorts of variations on that if you consider electroacoustic phenomena such as piezoelecricity.

Enough.
 
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