Posts tagged ‘Koch’

claustrumDoctors at George Washington found by chance recently that stimulating a patient’s claustrum served to disrupt consciousness temporarily (abstract). The patient was being treated for epilepsy, and during this kind of surgery it is normal to use an electrode to stimulate areas of the brain in the target area before surgery to determine their role and help ensure the least possible damage is done to important functions. The claustrum is a sheet-like structure which seems to be well connected to many parts of the brain; Crick and Koch suggested it might be ‘the conductor of the orchestra’ of consciousness.

New Scientist reported this as the discovery of the ‘on/off’ switch for consciousness; but that really doesn’t seem to be the claustrum’s function: there’s no reason at the moment to suppose it is involved in falling asleep, or anaesthesia, or other kinds of unconsciousness, The on/off idea seems more like a relatively desperate attempt to explain the discovery in layman’s terms, reminiscent of the all-purpose generic tabloid newspaper technology report in Michael Frayn’s The Tin Men:

British scientists have developed a “magic box”, it was learned last night. The new wonder device was tested behind locked doors after years of research. Results were said to have exceeded expectations… …The device is switched on and off with a switch which works on the same principle as an ordinary domestic light switch…

Actually, one of the most interesting things about the finding is that the state the patient entered did not resemble sleep or any of those other states; she did not collapse or close her eyes, but instantly stopped reading and became unresponsive – although if she had been asked to perform a repetitive task before stimulation started, she would continue for a few seconds before tailing off. On some occasions she uttered a few incoherent syllables unprompted. This does sound more novel and potentially more interesting than a mere on/off switch. She was unable to report what the experience was like as she had no memory of it afterwards – that squares with the idea that consciousness was entirely absent during stimulation, though it’s fair to note that part of her hippocampus, which has an important role in memory formation, had already been removed.

Could Crick and Koch now be vindicated? It seems likely in part: the claustrum seems at least to have some important role – but it’s not absolutely clear that it is a co-ordinating one. One of the long-running problems for consciousness has been the binding problem: how the different sensory inputs, processed and delivered at different speeds, somehow come together into a smoothly co-ordinated experience. It could be that the claustrum helps with this, though some further explanation would be needed. As a long shot, it might even be that the claustrum is part of the ‘Global Workspace’ of the mind hypothesised by Bernard Baars, an idea that is still regularly invoked and quoted.

But we must be cautious. All we really know is that stimulating the claustrum disrupted consciousness. That does not mean consciousness happens in the claustrum. If you blow up a major road junction near a car factory, production may cease, but it doesn’t mean that the junction was where the cars were manufactured. Looking at it sceptically we might note that since the claustrum is well connected it might provide an effective way of zapping several important areas at once, and it might be the function of one or more of these other areas that is essential to sustaining consciousness.

However, it is surely noteworthy that a new way of being unconscious should have been discovered. It seems an unprecedentedly pure way, with a very narrow focus on high level activity, and that does suggest that we’re close to key functions. It is ethically impossible to put electrodes in anyone’s claustrum for mere research reasons, so the study cannot be directly replicated or followed up; but perhaps the advance of technology will provide another way.

structureKristjan Loorits says he has a solution to the Hard Problem, and it’s all about structure.

His framing of the problem is that it’s about the incompatibility of three plausible theses:

  1. all the objects of physics and other natural sciences can be fully analyzed in terms of structure and relations, or simply, in structural terms.
  2. consciousness is (or has) something over and above its structure and relations.
  3. the existence and nature of consciousness can be explained in terms of natural sciences.

At first sight it may look a bit odd to make structure so central. In effect Loorits claims that the distinguishing character of entities within science is structure, while qualia are monadic - single, unanalysable, unconnected. He says that he cannot think of anything within physics that lacks structure in this way – and if anyone could come up with such a thing it would surely be regarded as another item in the peculiar world of qualia rather than something within ordinary physics.

Loorits approach has the merit of keeping things at the most general level possible, so that it works for any future perfected science as well as the unfinished version we know at the moment. I’m not sure he is right to see qualia as necessarily monadic, though. One of th best known arguments for the existence of qualia is the inverted spectrum. If all the colours were swapped for their opposites within one person’s brain – green for red, and so on – how could we ever tell? The swappee would still refer to the sky as blue, in spite of experiencing what the rest of us would call orange. Yet we cannot – can we? – say that there is no difference between the experience of blue and the experience of orange.

Now when people make that argument, going right back to Locke, they normally chose inversion because that preserves all the relationships between colours.  Adding or subtracting colours produce results which are inverted for the swappee, but consistently. There is a feeling that the argument would not work if we merely took out cerulean from the spectrum and put in puce instead, because then the spectrum would look odd to the swappee.  We most certainly could not remove the quale of green and replace it with the quale of cherry flavour or the quale of distant trumpets; such substitutions would be obvious and worrying (or so people seem to think). If that’s all true then it seems qualia do have structural relationships: they sort of borrow those of their objective counterparts.  Quite how or why that should be is an interesting issue in itself, but at any rate it looks doubtful whether we can safely claim that qualia are monadic.

Nevertheless, I think Loorits’ set-up is basically reasonable: in a way he is echoing the view that mental content lacks physical location and extension, an opinion that goes back to Descartes and was more recently presented in a slightly different form by McGinn.

For his actual theory he rests on the views of Crick and Koch, though he is not necessarily committed to them. The mysterious privacy of qualia, in his view, amounts to our having information about our mental states which we cannot communicate. When we see a red rose, the experience is constituted by the activity of a bunch of neurons. But in addition, a lot of other connected neurons raise their level of activity: not enough to pass the threshold for entering into consciousness, but enough to have some effect. It is this penumbra of subliminal neural activity that constitutes the inexpressible qualia. Since this activity is below the level of consciousness it cannot be reported and has no explicit causal effects on our behaviour; but it can affect our attitudes and emotions in less visible ways.

It therefore turns out that qualia re indeed not monadic after all; they do have structure and relations, just not ones that are visible to us.

Interestingly, Loorits goes on to propose an empirical test. He mentions an example quoted by Dennett: a chord on the guitar sound like a single thing, but when we hear the three notes played separately first, we become able to ‘hear’ them separately within the chord. On Loorits’ view, part of what happens here is that hearing the notes separately boosts some of the neuronal activity which was originally subliminal so that we become aware of it: when we go back to the chord we’re now aware of a little more information about why it sounds as it does, and the qualic mystery of the original chord is actually slightly diminished.

Couldn’t there be a future machine that elucidated qualia in this way but more effectively, asks Loorits?  Such a machine would scan our brain while we were looking at the rose and note the groups of neurons whose activity increased only to subliminal levels. Then it could directly stimulate each of these areas to tip them over the limit into consciousness. For us the invisible experiences that made up our red quale would be played back into our consciousness, and when we had been through them we should finally understand why the red quale was what it was: we should know what seeing red was like and be able for the first time to describe it effectively.

Fascinating idea, but I can’t imagine what it would be like; and there’s the rub, perhaps. I think a true qualophile would say, yes, all very well, but once we’ve got your complete understanding of the red experience, there’s still going to be something over and above it all; the qualia will still somehow escape.

The truth is that Loorits’ theory is not really an explanation of qualia: it’s a sceptical explanation of why we think we have qualia. This becomes clear, if it wasn’t already, when he reviews the philosophical arguments: he doesn’t, for example, think philosophical zombies, people exactly like us but without qualia, are actually possible.

That is a perfectly respectable point of view, with a great deal to be said for it. If we are sceptics,  Loorits’ theory provides an exceptionally clear and sensible underpinning for our disbelief; it might even turn out to be testable. But I don’t think it will end the argument.

 

Picture: ephaptic consciousness. The way the brain works is more complex than we thought. That’s a conclusion that several pieces of research over recent years have suggested for one reason or another: but some particularly interesting conclusions are reported in a paper in Nature Neuroscience (Anastassiou, Perin, Markram, and Koch). It has generally been the assumption that neurons are effectively isolated, interacting only at synapses: it was known that they could be influenced by each other’s electric fields, but it was generally thought that given the typically tiny fields involved, these effects could be disregarded. The only known exceptions of any significance were in certain cases where unusually large fields could induce ‘ephaptic coupling ‘ interfering with the normal working of neurons and cause problems.

Given the microscopic sizes involved and the weakness of the fields, measuring the actual influence of ephaptic effects is difficult, but for the series of experiments reported here a method was devised using up to twelve electrodes for a single neuron. It was found that extracellular fluctuation did produce effects within the neuron, at the minuscule level expected: however, although the effects were too small to produce any immediate additional action potentials, induced fluctuations in one neuron did influence neighbouring cells, producing a synchronisation of spike timing. In short, it turns out that neurons can influence each other and synchronise themselves through a mechanism completely independent of synapses.

So what? Well, first this may suggest that we have been missing an important part of the way the brain functions. That has obvious implications for brain simulations, and curiously enough, one of the names on the paper (he helped with the writing) is that of Henry Markram, leader of the most ambitious brain simulation project of all,Blue Brain.  Things seem to have gone quiet on that project since completion of ‘phase one’; I suppose it is awaiting either more funding or the advances in technology which Markram foresaw as the route to a total brain simulation. In the meantime it seems the new research shows that like all simulations to date Blue Brain was built on an incomplete picture, and as it stood was doomed to ultimate failure.

I suppose, in the second place, there may be implications for connectionism. I don’t think neural networks are meant to be precise brain simulations, but the suggestion that a key mechanism has been missing from our understanding of the brain might at least suggest that a new line of research, building in an equivalent mechanism to connectionist systems could yield interesting results.

But third and most remarkable, this must give a big boost to those who have suggested that consciousness resides in the brain’s electrical field: Sue Pockett, for one, but above all JohnJoe McFadden, who back in 2002 declared that the effects of the brain’s endogenous electromagnetic fields deserved more attention. Citing earlier studies which had shown modulation of neuron firing by very weak fields, he concluded:

By whatever mechanism, it is clear that very weak em field fluctuations are capable of modulating neurone-firing patterns. These exogenous fields are weaker than the perturbations in the brain’s endogenous em field that are induced
during normal neuronal activity. The conclusion is inescapable: the brain’s endogenous em field must influence neuronal information processing in the brain.

We may still hold back from agreeing that consciousness is to be identified with an electromagnetic field, but he certainly seems to have been ahead of the game on this.

Phi

Picture: Phi. I was wondering recently what we could do with all the new computing power which is becoming available.  One answer might be calculating phi, effectively a measure of consciousness, which was very kindly drawn to my attention by Christof Koch. Phi is actually a time- and state-dependent measure of integrated information developed by Giulio Tononi in support of the Integrated Information Theory (IIT) of consciousness which he and Koch have championed.  Some readable expositions of the theory are here and here with the manifesto here and a formal paper presenting phi here. Koch says the theory is the most exciting conceptual development he’s seen in “the inchoate science of consciousness”, and I can certainly see why.

The basic premise of the theory is simply that consciousness is constituted by integrated information. It stems from the phenomenological observations that there are vast numbers of possible conscious states, and that each of them appears to unify or integrate a very large number of items of information. What really lifts the theory above the level of most others in this area is the detailed mathematical under-pinning, which means phi is not a vague concept but a clear and possibly even a practically useful indicator.

One implication of the theory is that consciousness lies on a continuum: rather than being an on-or-off matter, it comes in degrees. The idea that lower levels of consciousness may occur when we are half-awake, or in dogs or other animals, is plausible and appealing. Perhaps a little less intuitive is the implication that there must be in theory be higher states of consciousness than any existing human being could ever have attained. I don’t think this means states of greater intelligence or enlightenment, necessarily; it’s more  a matter of being more awake than awake, an idea which (naturally enough, I suppose) is difficult to get one’s head around, but has a tantalising appeal.

Equally, the theory implies that some minimal level of consciousness goes a long way down to systems with only a small quantity of integrated information. As Koch points out, this looks like a variety of panpsychism or panexperientialism, though I think the most natural interpretation is that real consciousness probably does not extend all that far beyond observably animate entities.

One congenial aspect of the theory for me is that it puts causal relations at the centre of things: while a system with complex causal interactions may generate a high value of phi, a ‘replay’ of its surface dynamics would not. This seems to capture in a clearer form the hand-waving intuitive point I was making recently in discussion of Mark Muhlestein’s ideas.  Unfortunately calculation of Phi for the human brain remains beyond reach at the moment due to the unmanageable levels of complexity involved;  this is disappointing, but in a way it’s only what you would expect. Nevertheless, there is, unusually in this field, some hope of empirical corroboration.

I think I’m convinced that phi measures something interesting and highly relevant to consciousness; perhaps it remains to be finally established that what it measures is consciousness itself, rather than some closely associated phenomenon, some necessary but not sufficient condition. Your view about this, pending further evidence, may be determined by how far you think phenomenal experience can be identified with information. Is consciousness in the end what information – integrated information – just feels like from the inside? Could this be the final answer to the insoluble question of qualia? The idea doesn’t strike me with the ‘aha!’ feeling of the blinding insight, but (and this is pretty good going in this field) it doesn’t seem obviously wrong either.  It seems the right kind of answer, the kind that could be correct.

Could it?