Where does consciousness come from?
March 17, 2009Consciousness arises as an emergent property of the human mind. Yet basic questions about the precise timing, location and dynamics of the neural event(s) allowing conscious access to information are not clearly and unequivocally determined. Some neuroscientists have even argued that consciousness may arise from a single "seat" in the brain, though the prevailing idea attributes a more global network property. Do the neural correlates of consciousness correspond to late or early brain events following perception? Do they necessarily involve coherent activity across different regions of the brain, or can they be restricted to local patterns of reverberating activity?
A new paper, published in this week's PLoS Biology, suggests that four specific, separate processes combine as a "signature" of conscious activity. By studying the neural activity of people who are presented with two d ifferent types of stimuli - one which could be perceived consciously, and one which could not - Dr. Gaillard of INSERM and colleagues, show that these four processes occur only in the former, conscious perception task.
This new work addresses the neural correlates of consciousness at an unprecedented resolution, using intra-cerebral electrophysiological recordings of neural activity. These challenging experiments were possible because patients with epilepsy who were already undergoing medical procedures requiring implantation of recording electrodes agreed to participate in the study. The authors presented them with visually masked and unmasked printed words, then measured the changes in their brain activity and the level of awareness of seeing the words. This method offers a unique opportunity to measure neural correlates of conscious access with optimal spatial and temporal resolutions. When comparing neural activity elicited by masked and unmasked words, they could isolate four converging and complementary electrophysiological markers characterizing conscious access 300 ms after word perception.
All of these measures may provide distinct glimpses into the same distributed state of long-distance reverberation. Indeed, it seems to be the convergence of these measures in a late time window (after 300 ms), rather than the mere presence of any single one of them, which best characterizes conscious trials. "The present work suggests that, rather than hoping for a putative unique marker - the neural correlate of consciousness - a more mature view of conscious processing should consider that it relates to a brain-scale distributed pattern of coherent brain activation," explained neuroscientist Lionel Naccache, one of the authors of the paper.
The late ignition of a state of long distance coherence demonstrated here during conscious access is in line with the Global Workspace Theory, proposed by Stanislas Dehaene, Jean-Pierre Changeux, and Lionel Naccache.
More information: Gaillard R, Dehaene S, Adam C, Clémenceau S, Hasboun D, et al. (2009) Converging intracranial markers of conscious access. PLoS Biol 7(3): e1000061. doi:10.1371/journal.pbio.1000061
http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.1000061
Source: Public Library of Science (news : web)
Jun 10, 2008 |
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Consciousness in this context is a narrowly constrained, packaged form of the term that we use in ordinary language. For instance, it doesn't (read: can't) include the "what it's like" sense of the word which is so crucial to its everyday usage. It's a functional description; it describes certain kinds of cognitive processes, rightly or wrongly.
Non-local consciousness isn't a "slap in the face" to mind-body identity. It just means that the brain processes that subserve it are more complex and distributed than, say, the brain processes that construct a somatotopic body map. It's naive to construe these results as showing that consciousness is "correlated with," rather than "arising from," brain activity. Consciousness IS brain activity, it's just that it's very complicated. The authors that support Global Workspace Theory would hold that it's something that arises from the competition and collaboration between distributed, functionally segregated, modular brain processes.
I mean, all you have to do to show that consciousness is caused by brain activity is take a drink of alcohol. As the ethanol crosses the blood-brain barrier, it will induce changes in GABA functionality, and voila--your state of consciousness is altered. All because the way that a certain neurotransmitter acts is changed.
The only difference between saying one thing causes another and one thing is correlated with another is that in the latter case you can say that there's some third variable controlling the two, or two correlated variables controlling the two etc. What variable would that be? Clearly brain activity is what determines consciousness. The difficult point is that even though this is true, it may be impossible to reduce consciousness to brain activity with some sort of theoretical model. It's hard to reconcile those two points, but they must be reconciled. Consider ant colonies--clearly, nothing else composes them but ants, but it's hard to account for all of the colony-wide activity by looking at single ants. This is because the emergent phenomenon we're concerned with is complex, in the sense of complex mandated by complexity theory.
I agree, but that partial treatment then also limits the claims you can make. So you can't say that all aspects of consciousness arise from brain behaviour if you are saying you can't include all aspects of consciousness in your study. Someone should invent another word to avoid the confusion. I've seen Consciousness and consciousness to cover the different definitions, but I would prefer that the brain aspect got a different word altogether. Neuroconsciousness maybe? = what the neurons are doing during conscious experience? That still leaves open what consciousness is and what experience is, and shows the limitation of the field of study.
What is usually done is to refer to NCC, or 'neural correlates of consciousness'. This then avoids making the claim that you explain all aspects of C as having arisen causally from the brain processes. The subjective aspect or qualia are indeed something else entirely from the NCC and all we can say for certain at the moment is that the 2 are correlated.
Colin McGin is by no means unique in this regard. I can at once think of Stapp, Goswami, Wilber, William James, Sheldrake, Dalai Llama etc. etc. You may laugh at some of these but I laugh at Dennett and his ilk. Any Tucson conference has a broad mix, and by no means is a large majority of the emergent school. Thumb through JCS.
On the contrary I would say that it's the correlation that's just very complex. It's naive to posit a direct identity of mind and brain when the jury is out on so many aspects of qualia etc. And Baars' Global Workspace Theory can be seen as evidence for the homunculus: a play on a stage where the audience is not only silent subconscious servants of H, but H herself.
If I had a nickel for every time - The answer to that is, of course that it's all about QUALIA i.e. qualitative, not quantitative experience. So when I knocked back that Guinness on St. Pat's day I remained that eternal diamond within, though the qualia's knobs were tweaked for the on -looking homunculus .
How about soul for one? For 99.9% of history and 90% of present populace, the idea of what Jung called an extramundane reality was very much a part of the equation. Only with Victorian clockworkism did it suffer a decline. Some neuroscientist / philosophers are still Victorian and never heard of quantum weirdness. As in Q weren't enough, psychic stuff is also not dismissed just by ignoring it. See Dead Radin's "Entangled Minds" or read William James on his white crow, Mrs. Piper. All that implies that in the spirit of Goedel, there is more in Heaven and Earth tan is dreamt of in your philosophy.
so what do you make of the actual research: "The present work suggests that, rather than hoping for a putative unique marker - the neural correlate of consciousness - a more mature view of conscious processing should consider that it relates to a brain-scale distributed pattern of coherent brain activation," ?
a question that Salo seems to say is not/cannot even be addressed. Although that doesn't seem to stop him saying that it's due to complex brain activity, even though that may be impossible to prove with a model (which would make such a view an opinion, no?).
McGinn discusses this inner dimension of the subjective very well. In his book 'Mysterious flame' he makes it clear that thoughts are not anywhere in normal space but in that iner space, as is that huge sim of the 'external' world that's out virtual reality consciousness.
What they seem to be saying there, is simply that instead of local NCC (note: the authors of the paper are in fact less reductionist in their phraseology than the reporter who wrote the above) one should consider the distributed or non-local NCC - funny, as that, as along with temporal extension in the 300 ms window this is just the binding problem, both spatial and temporal.
Indeed - as so many commentators in this field, a blunt statement 'it is so' is often taken as proof. But indeed it is more an opinion, as are all ideas about C, which is why it's a mystery.
The larger questions cannot be solved by scientific reductionism, for they are too complex and defy isolated analysis. Compartmentalization gets a big red FAIL sticker on it's forehead, with regards to this subject.
Some might even go as far as to feel and think that science as a system of compartmentalized reductionism has met it's limit of usefulness. Some might even be paranoid enough to call it what they feel it is: a system of keeping man under control, with regards to looking too far into itself.
This, when viewed with eyes that look to larger questions than science may, can, or allows itself - via it's self imposed circular and butt staring 'rigid rules'. The word anal is contained within 'Analysis' for a reason, you know. And no, it's not the Greeks.
If we assume that the brain does it all then we are basically saying that an ensemble of atoms can be conscious but if one can then why others cannot? Since we don't know what properties such an ensemble has to have it is possible that many things around us are also conscious, they just can't communicate that to us. For example if a constellation of atoms can be conscious then maybe a constellation of stars can also.
In fact people also cannot communicate to us they are conscious, we just assume they are since they act similar to us. There is no way you can prove you are conscious to others, a deterministic program could simulate all the aspects of consciousness. This suggests that consciousness is just an illusion.
On the other hand there is this very persistent perception of being which suggests it's not an illusion, pain certainly seems all too real. This pain somehow manifests itself in the projection we have of our own body, this projection is likely created by neurons, and it somehow forces us to act in a certain way in response to pain. Or maybe we just think we act in a certain way when in fact we only observe everything passively while rationalizing reactions as our own to keep the illusion we are in control? But even if we strip free will like this it still leaves the problem of observer, why is he there and what is he made from?
As already said if the brain somehow manages to create such a persistent projection of reality it means that matter in general has some properties which facilitate it somehow. The brain just evolved to take advantage of it in the local arms race between chemical on the surface of this planet. But at what point in evolution did it happen? Are other mammals also conscious? reptiles? fish? flies? amoebas? bacteria? Do bacteria also have a projection of their bodies and feel pain when a phage punches through their lipid bilayer? Does a protein feel something when it changes conformation? Is every physical process accompanied by some sort of tiny bit of consciousness?
There is also the problem of time, physics suggests time is similar to space but why then do we only perceive a single moment of it? Is it all that exist or do we only have access to a single moment?
Too bad physics still struggles with the grand unified theory since the properties of both time and matter play a fundamental role in the problem of consciousness and a better model of physical reality is our best bet to make progress here.
I am a layman with no special knowledge of this subject but like many people have pondered the enigma of consciousness, which is how can any physical matter give rise to C?
Ultimately I came to my current view which is similar to that by Superhuman. It seems to me that if physical stuff can give rise to consciousness then all matter may have the potential for consciousness, that it may be a property of matter such as mass and atomic weight for example, and may vary across the elements as other atomic properties do. Some arrangements of atoms may enhance the property as in the case of iron for example; when its electron spins are aligned it expresses magnetism, the more aligned they are greater the magnetism.
There are enough unsolved problems in physics to leave room for some as yet unknown properties or forces to be discovered.
Beings with a brain that gives rise to various senses such as sight, touch, and smell, provide input to the beings 'consciousness' (arising from matter) thus generating the profound sense of being that we all experience.
True, but I think most of us would refute that this is the case because of our profound sense of being.
My view is that the sense of consciousness experienced by beings will be qualified by the sensory inputs it has and the abilities it's 'brain' gives it for expression and mobility. So to answer your question I think, until proven otherwise, that all living things have a degree of consciousness relative to their senses.
I completely agree but I also have the depressing thought that our brain is not equal to the task. Why should our brain be able to comprehend such mysteries as the origin of the universe and the problem of consciousness. It is just a small lump of matter after all which evolved through natural selection to enable us to cope with our environment. We humans are trying to use it for a purpose for which it was never designed.
Our most successful theory, quantum physics, gives rise to physical behaviour which seems only to be 'understood' in terms of mathematics, no human that I am aware of claims to have a conceptual understanding of the quantum nature of matter. Perhaps we never will, and thus may never have an understanding of consciousness. Unless we can somehow engineer a 'better' brain...