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.


  1. 1. Jessica says:

    This is amazing. A discovery like this could help uncover new mysteries about those who are in a coma. Its also very unnerving knowing one can now temporarily disrupt consciousness of an individual. Could there really be an on/off switch to the conscious?

  2. 2. Callan S. says:

    It looks like it’s near the connection point between the two hemispheres of the brain. The same thing they used to sever as an epilepsy ‘treatment’

    The ‘continuing the task briefly even while unconcious’ is both spooky and yet something predicted.

  3. 3. Callan S. says:

    Oh, and I wouldn’t call it on/off. More like crashing your brain, with all the persona loss that might come with that (again, see the reference to prior epilepsy ‘treatments’ of essentially slicing the brain in half)

  4. 4. Vicente says:

    Very interesting !!

    I think this seredipity is going to bring us good times… I hope they can find some non-intrusive way to mess around with somebody’s claustrum.

    Maybe Descartes missed the shot by half an inch.

    From wikipedia:

    The claustrum has a phylogenetic background appearing predominantly in insectivores, Prosimians, and Marsupials. It is difficult to trace where the evolution of the structure originated what a pity !!

    One interesting aspect about the claustrum is the lack of cell types. In most parts of the brain, especially in the cortical regions, there is considerable differentiation of cell types, giving way to a number of functions. In the claustrum, as Dr. Crick and others pointed out, there are three main types of cells.[2] The first, which is deemed Type 1, is large with spine-covered dendritic processes. These cells receive input as well as project back toward various regions, both laterally and medially. The other two types of cells do not have spines, but can be told apart based on the cell body size. However, both are restricted to the claustrum and, thus, are labeled interneurons.

    The truly interesting thing about the claustrum, however, is how it can take in multiple information modalities, including motor, visual, and auditory . It has even been shown that the same cells can process information across all these types, even though there is some semblance of segregation across a single type of information.

    What about animals without claustrum? is there a proto-claustrum?

    It is vital to access this organ, and with the higher possible space resolution, is it the whole claustrum, or just some of neurons in it?

  5. 5. Hunt says:

    Interesting that this is (I hesitate to say “exactly,” but…) exactly how a very complex machine might be predicted to react. Some central relay has been unset, while certain subsidiary functions continue to react for a while. Like an exceedingly delicate washing machine (now there’s a metaphor) has had some key solenoid triggered.

    And some people still insist there is a ghost in the machine.

  6. 6. Vicente says:


    I do still insist there is a “ghost” in the machine, and you have no evidence to prove me wrong…neither have I about you, except for qualia and my own experience… which of course is just personal.

    To come to your conclusion we don’t need this interesting discovery about the claustrum… evidence already gathered shows that consciouness relies on the brain.

    What about this other metaphor: The brain is just an interface (a transponder) to interact with this Universe layer, through random processes biasing (microtubules quantum states colapsing, synapses vesicles exocytosis modulation,…), so that the physical causal net is preserved…

    If you jam the antenna (e.g. the claustrum) signal is lost…

    If a certain house internet provider (ISP) has a problem with the servers, and you can’t communicate for a while with the people in that house, which use IP services, TV, IP voice phone,e-mail, chats, wassap, all… you can’t conclude that they are bots that were turned off because of the ISP outage.

    It’s not that easy… one thing is scientific data/evidence and a very different thing is the philosophical interpretation of them. In the current paradigm everything is messed up, and data and its interpretation are put at the same level. Big mistake.

  7. 7. Hunt says:

    The idea that the brain is some type of interface, transponder, “receiver,” or in general, a go-between from here to some ethereal plane of the universe, will become less sensible the more specific structures become known and available to study. Yes, so I’m taking a side here. The concept of qualia, though it strikes us as bizarre, does not hold for me a formal enough scientific impasse to secure that your opinion is correct.

    Naturally I can’t present a formal argument against it; however to me the brain appears complex enough to explain consciousness on its own without reference to non-conventional scientific explanation, and I assume that’s what you mean, and not some religious spiritual cause. Of course, this is just my intuition.

    Unfortunately, evolutionary argument against you seem no good to me, since evolution will make use of any physical process, known, conventional, or unknown. Perhaps you are right, but I suspect not.

  8. 8. Hunt says:

    It occurs to me that the matter essentially boils down to something analogous to Hume’s argument against miracles. In order for you to be right, it is necessary that there is a fundamental realm of reality that we have so far overlooked. Is the credibility of this greater than the idea that things like qualia, inexplicable personal experience, etc. have conventional physical causes? If so, then your belief is justified.

    Unfortunately, I guess I’d have to conclude for the moment that the matter is a draw, for the world is a very strange place indeed.

  9. 9. Vicente says:


    “non-conventional scientific explanation, and I assume that’s what you mean, and not some religious spiritual cause”

    Yes, this is the case. Reality is one. How to observe and describe it (to understand) is the problem.

    In this sense:

    “a fundamental realm of reality that we have so far overlooked”

    Nope, not overlooked, it is probably the one we have looked at the most, but we are unsuccessful when trying to integrate it with current physics. In fact, physics, as knowledge, exist as part of this “realm”. Everything seems paradoxical to me.

  10. 10. Callan S. says:

    Vincente, what if, in your hypothesis, you could jam the signal to the brain. Cutting it off from – whatever? Given the post you might acknowledge it could do repetitive tasks, perhaps even walk around.

    What if the brain and body could do alot of other things as well, even cut off?

  11. 11. Vicente says:


    I don’t know, depends on how this jamming is done. In the case of this patient, she was just shut down. I suppose that it depends on what systems are disabled by the “jamming”. If the interference mechanism impacts on the brains’ required info flow for those tasks, then the whole system would be turned off.

    I have seen decapitated hens running around (extreme jamming).

    The problem is that the brain operates in an auto-pilot mode a lot, and this is a degraded mode of consciouness we should try to avoid.

    In the case of philosophical zombies this “full-duplex” signal is absolutely interrupted and all tasks can still be performed. Epiphenomenalism just allows a one direction info flow, with no control signals…

    Most drugs (specially psychedelic ones) jam (signal spoofing?) (by jamming, in this case, I mean standard functions disturbance) this signal, with a clear impact on conscious states, still people could possibly carry out repetitive tasks.

    Strictly speaking the action is done on the “transponder” (the brain), not really on the signal (whatever that is).

  12. 12. Callan S. says:

    I think it’s fair to consider a jamming which simply occurs at the ‘reciever modules’ in your hypothesis, without everything else being shut down as well.

    What about memory – is it brain based or signal based in your hypothesis? What is amnesia, in regards to it?

  13. 13. Vicente says:


    Memory is a complicated issue. The question to me is: if we have memories of past experiences stored outside the brain (in our “real self”), why is it that we cannot retrieve them?

    I don’t know. I could speculate that the connection mechanism to the brain forces the attention focus to be fully channeled through it (in ordinary conditions). Sort of wearing an augmented reality hud… similar to the matrix idea. So in ordinary conditions we have to rely on our brain RAM and HD to operate. There are monks and meditators that report being able to access to this global memory. As usual personal experiences can’t be conveyed. I have my own experience to this respect.

    Then, memory is to do with time, with the way we perceive the passing of time in this life, so maybe, in a “more unified” scenario, there is a different concept of time and memory could be understood in a different way.

    We can make many conjectures… any idea?

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