Disembodied trippers

As regular readers know, I have cited before a very interesting study recently done in the UK on the effects of psilocybin (the active ingredient of magic mushrooms) on the brain. The study caught my attention because preliminary reports suggested that the researchers observed only reductions in brain activity while subjects were having unfathomable psychedelic trips. This, of course, is counter-intuitive: If the hallucinations are not being caused by drug-induced brain activations, where does the trip come from? Now, finally, the complete scientific paper containing the results of the study has been published in the Proceedings of the National Academy of Sciences of the USA. Summaries have also been published in Nature and in Scientific American. Here, I'd like to discuss these results in a little more depth than I did before.

To me, what is of significance in this work is not the psychedelic connection, but the idea that extremely intense subjective experiences can occur without accompanying brain activations; a kind of disembodied experience, if you will, which seems to contradict the currently-accepted notion that the brain generates consciousness. Preliminary reports on this study already indicated that the researchers had observed a reduction of brain activity, but the explanation could have been that the drug selectively affected inhibitory brain processes, thereby allowing excitatory processes to grow unchecked elsewhere. Let me unpack this a bit for you: Inhibitory brain processes are like bouncers guarding the entrance of the club of consciousness. Excitatory brain processes become conscious if they get into the club, but the bouncers prevent many from entering, so we never become aware of them. If the drug takes out the bouncers, the idea is that many excitatory processes that would otherwise remain unconscious now can flood into the club. This would explain the 'trip.'

The problem, having now studied the paper carefully, is that the researchers observed no brain activation anywhere. Quoting the paper: "we observed no increases in cerebral blood flow in any region." You see, if the club of consciousness got flooded because the bouncers were taken out, the researchers should still have seen the increases in blood flow corresponding to the excitatory processes now invading the unguarded club of consciousness. But they didn't. In fact, they observed that the more the drug de-activated the brain, the more intense were the subjective experiences reported by the subjects. This is profoundly anomalous. Subjects reported experiences like "geometric patterns," "extremely vivid imagination," seeing their "surroundings change in unusual ways," as well as experiences with a "dream-like quality." Without brain activations observed anywhere, and with the subjects stuck inside an fMRI scanner, I ask you: Where did all these experiences come from? One would expect, for instance, visions of geometric patterns to be caused by activations of visual areas of the brain. But the researchers not only did not observe these activations, they reported that "there were ... additional ... signal decreases ... in higher-order visual areas." How is this possible? It suggests that the unfathomable experiences of a psychedelic trip are disembodied, occurring somehow outside the brain; a disembodied tripper, if you will.

If you want to have an idea of the kind of structured, coherent, evocative, and unfathomably intense subjective experiences that people have under the effect of psilocybin, I recommend the Erowid experiences vault. If you browse through those reports, you will likely convince yourself that, if consciousness is indeed merely the result of brain activity, it is inconceivable that such experiences could occur without the brain lighting up like a Christmas tree. Yet, the opposite happens; the brain largely goes to sleep. Who, then, is having the trip? It doesn't seem to be the brain.

As I mentioned earlier, I have cited this British study before as a way to substantiate my hypothesis that the brain is a mechanism for localizing and limiting consciousness to a space-time locale, but does not generate consciousness. Surprisingly, the researchers acknowledged this explicitly in the paper by referring to Aldous Huxley's analogous idea of the brain as a reduction valve of consciousness. They wrote: "This finding is consistent with Aldous Huxley's 'reducing valve' metaphor ... which propose[s] that the mind/brain works to constrain its experience of the world." To help you know precisely what Huxley's hypothesis was, here is a quote from pages 10 and 11 of his book The Doors of Perception and Heaven and Hell (2004 edition):

"The suggestion is that the function of the brain and nervous system and sense organs is in the main eliminative and not productive. Each person is at each moment capable of … perceiving everything that is happening everywhere in the universe. The function of the brain and nervous system is to protect us from being overwhelmed … by shutting out most of what we should otherwise perceive or remember at any moment, and leaving only that very small and special selection which is likely to be practically useful."

Also interesting is the researchers' observation that the highest de-activations of the brain occurred in areas associated to what we normally call "ego functions;" namely, the default-mode network. This is consistent with the age-old idea that the ego prevents us from seeing reality as it truly is; from perceiving the unity and transcendence of conscious experience. As I wrote earlier in this blog, I like the metaphor of the brain as a whirlpool of consciousness, which localizes consciousness like a whirlpool localizes the water of a stream. When I read this part of their paper, I couldn't help but visualize the de-activation of the ego functions as analogous to someone inserting one's hand in a whirlpool, disrupting the "loopy" flow that maintains it, and thereby allowing the water molecules originally trapped in it to escape.

Technically, the study seems extremely well designed. To counter the uncertainties of measuring brain activity with an fMRI scanner, the researchers used two different signals: Arterial Spin Labelling (ASL) and a Blood-Oxygen Level-Dependent (BOLD) signal. The results across the two were consistent. Several other protocols were used to tackle each conceivable loophole and ensure the reliability of the results. Moreover, the researchers were able to explain why earlier studies on the effect of psychedelics on brain activity seemed to lead to different conclusions: Because earlier studies used PET scan measurements over much greater time scales, they may have detected merely a "rebound" of the psilocybin effects on glucose metabolism. All in all, the study is compelling and clearly carried out with great care and professionalism.

To conclude, I think that, although this research represents a milestone in our understanding of the relationship between mind and brain, it is just one study. Its results must be replicated before definite conclusions can be arrived at. Yet, there is a broader pattern associating peak subjective experiences with reduced blood flow to the brain, as I wrote in another article. Taken together, this study and that broader pattern are extremely compelling. They strongly indicate that the brain is a mechanism for limiting and localizing consciousness, but does not generate consciousness. When some specific brain functionality is taken out, consciousness relaxes and expands. Death, seen this way, may be the ultimate liberation of subjective experience.

Copyright © 2012 by Bernardo Kastrup. All rights are reserved.


  1. I nipped over from Skeptiko to read this, Bernardo. The more I read about the study, the more interesting it becomes.

    I had this passing thought about the state of play wrt DNA and the human genome project, where much fewer genes than were expected have been found, and I've read suggestions that DNA just enables protein production - it doesn't explain how the body is formed, really.

    Maybe there's a kind of parallel here - just as the brain could be a receiver and limiter of consciousness, maybe the protein production system is just a means of producing body-stuff, which gets organised by some kind of morphogenetic signal that is as non-material as consciousness - tantalising links with evolutionary processes too?

    At any rate, my ideas about this are a bit vague at the moment, so I'll think some more on it - thanks for your article! :-)

    Michael Larkin

  2. That was very interesting.

    I was particularly keen to see that they had taken extra care to ensure that the fMRI was done correctly, because I have always been wary of fMRI results after reading this:


    I guess this links with quite a lot of other evidence in support of your theory. NDE's (obviously), but also perhaps Persinger's electromagnetically induced altered states of consciousness, where the electromagnetic signal is seen as something that disrupts the functioning of a brain area - roughly equivalent, perhaps, to suppressing it chemically!

    David (also from Skeptiko)

    1. Hi David,
      Yes, the study had strong protocols to ensure that the fMRI signal corresponded to the paremeters they wanted to measure. Here is a segment of the paper:

      "Physiological Correction and Breath-Hold. BOLD and ASL fMRI measure changes in a vascular signal that is coupled to changes in neural activity. It is therefore important to address factors that may modulate brain vasculature without affecting neural activity. For example, increases in blood carbon dioxide that occur with changes in respiration can drive increases in CBF (7). Thus, to address the possibility that the effects observed in this study were driven by nonneural physiological changes, physiological variance (i.e., heart rate, respiration rate, and respiration depth) was regressed from the functional data before repeating the BOLD analyses described above. This correction step did not significantly alter the statistical parametric maps (Fig. S3), suggesting that changes in physiological parameters were not responsible for the positive outcomes.
      Furthermore, to test the possibility that psilocybin had acted directly on the cerebral vasculature, we included a blocked breathhold paradigm at the end of each BOLD scan. Hypercapnia is known to significantly increase the BOLD signal via CO2-induced vasodilation (see ref. 7 and Fig. S4); thus, it was reasoned that a direct effect of psilocybin on brain vasculature would cause an altered BOLD response to breath-hold. However, no difference was found in the BOLD response to breath-hold under psilocybin and placebo, implying that the drug had not acted directly on the vascular system."

    2. Scientists can be a little dry....I am an art dealer and a writer....I have been seriously meditating on God since 1970....on this drug I feel I have Mozart in the room with me when I write or create...THAT should be enough!!!!

    3. For this to really work your body has to be quite free of other toxins such as in coffee, cigarettes, alcohol......or anti-depressants and being a vegetarian does not hurt either...meat has fear toxins in it....and as with anything there are different levels of this drug...you need to get a very pure version....not polluted with ANYTHING else....I wish great artists like F. Scott Fitsgerald had this to turn to instead of alcohol....he and other artists who yurned to alcohol would have lived a lot longer AND created better!....to compare alcohol with this is ridiculous....this in it's purest form is the highest form of "Soma Rasa"(see google) on the earth planet...I am convinced.....I take very little....after a while I feel the human body learns from the drug and starts to manufacture it on it's own!!!!

  3. Bernardo, what do you think about the Scientific American article when it says "And according to Keith Laws, a neuropsychologist at the University of Hertfordshire, UK, the results could be explained in another way. "Deactivation of the mPFC and PCC are linked to anxiety and anticipation of pleasant and unpleasant experiences," he says. "This is a stressful situation, even for experienced drug users, and I suspect that they measured something to do with anxiety."

    It seems a bit weak as an explanation of the phenomenon for me.

    Valentino1971 (Skeptiko forum)

    1. Hi Valentino,
      I find it a naive and uninformed suggestion by Laws. The study had a placebo protocol. That is, they put people under the exact same experimental conditions, inside an fMRI, and injected them with a saline solution. If Laws were right, that should still have induced the deactivation, for the anxiety and anticipation were all still there. In fact, all de-activations reported in the paper correspond to changes in activation compared to this placebo baseline. So whatever results they measured, were unrelated to any other factors except the drug. I wonder if Laws read the paper.

  4. Quick question: were the subjects and technicians blinded? Subtle expectations unconsciously transmitted can have huge influences, hence my concern.

    1. No. As far as I could read in the paper, the study did not have a double-blind protocol. But then again, the idea that the researchers' expectations could cause a psychedelic trip on somebody else, and drastically alter their brain activations, would be even more spectacular evidence against the idea that the mind is generated by the brain, wouldn't it?

  5. ...but it would support Hall's suggestion that nervous anticipation resulted in those fMRI differences. No?

    1. My impression from the paper is that the volunteers did not know whether they were getting placebo or psilocybin (though I think the researchers did). So I think the study did have a blind protocol, but not a double-blind one. You would possibly be right if the volunteers knew what they were getting. But if they didn't, then the placebo baseline would eliminate the possibility that anticipation was causing the effect observed. I would be surprised if they had a placebo protocol without it being blind to the volunteers; it would defeat the purpose of a placebo. So I think we can safely assume that there was a blind protocol and that your concern is not applicable.

  6. Thank you for replying. My only remaining concern would be if (for example)a subject is given placebo initially, doesn't feel anything and then can deduce that the next infusion will be the psilocybin. This knowledge will create even more anticipation than during the placebo trial and create the differences found in brain activation. Does the design rule out this simple explanation? Thank you again.

    1. Michael, I think there is nothing at all simple about supposing that mere anticipation can explain how people can trip out of their minds while their brain shuts down. Now, all volunteers were experienced psychedelic users who knew what was coming. Moreover, half of the volunteers got the drug on the first scan, not the second.

  7. Why cannot one part of the brain act to dampen another part of the brain? Thus, if the first part (the dampener) were to be quieted, then the second part -- though still acting normally, without showing signs of excitation -- would produce a heightened subjective experience? This scenario would explain how one could have heightened subjective experiences without any part of the brain showing excitation, and without having to introduce the idea of mega-consciousness to account for the effect.

    1. According to your hypothesis, I can see two different scenarios:

      Scenario 1: The reduced inhibition could cause ordinarily subconscious excitatory processes, already in the placebo baseline of brain activity, to cross the threshold of awareness without any increase in their metabolic rate. This way, no delta in activation levels would be observed with the fMRI. Now, it is well-known in the psychedelic literature (see, for instance, Dr. Rick Strassman's "DMT: The Spirit Molecule") that psychedelic trances are extremely intense and often described as "more real than real." If subjective experience is brain activation, one would expect the intensity of the experiences to be proportional to the intensity of the corresponding brain activations. Therefore, activations behind psychedelic trips should be much higher than the placebo baseline. This alone seems to already contradict this first scenario, but let us pursue this a little further. Mushroom 'trips' entail structured and complex contents like voyages through 'intergalactic space,' 'hyper-dimensional fractal' displays, and conversations with 'entities' often described as 'aliens' or 'elves' (see the 'trip' reports in Erowid's mushroom experience vault). Therefore, this first scenario implies that unfathomable 'sci-fi' fantasies are subconsciously playing themselves out in our brains on a regular, on-going basis. What evolutionary advantage could this possibly have? Finally, we know that there is a relationship between subconscious processes and dreams. Yet, when we dream of something as dull as the clenching of a hand, the brain lights up with excitatory processes that are clearly visible with an fMRI scanner. Shouldn't, then, obvious activations corresponding to these on-going subconscious fantasies regularly pollute any fMRI measurement in an unmistakable way?

      Scenario 2: Perhaps there are no subconscious sci-fi fantasies ordinarily going on in the brain, but merely subconscious 'noise.' Then, when the drug de-activates certain (inhibitory) control centres in the brain, this subconscious noise could, by some unknown mechanism, coalesce in the form of a psychedelic 'trip,' and yet with no change in its metabolic signature. This way, the corresponding brain activations would be masked by the placebo baseline measurements. Now, think about this for a moment. This second scenario implies that the brain activation signatures of unfathomable and mind-boggling psychedelic 'trips' are indistinguishable from ordinary, subconscious 'noise.' How reasonable a hypothesis is this, in light of the assumption that experience is brain activity?

      Here is the take-away message: When we dream of something as inconsequential as the clenching of a hand, the brain lights up in an fMRI, compared to the normal baseline (I will publish a link to a study on this later on). But when we trip out of our heads, into intergalatic space, no activation can be seen compared to the normal baseline. Give this some honest thought before you conclude that there is nothing extraordinary to these results.

    2. Here is the study I referred to above: http://www.newscientist.com/article/dn20934-dreams-read-by-brain-scanner-for-the-first-time.html

  8. Agreed, it is an amazing study but I would have preferred a double-blinded protocol that controlled for inferred anticipatory effects (those I discussed earlier) to obviate the criticism of Hall. Also Frans Vollenweider using orally ingested psilocybin found activations not deactivations! If this study can be repeated under these more exacting standards then this will be momentus but until then....
    Michael Duggan.

  9. Bernardo, you might be interested in James L. Kent's book, "Shamanism in the Age of Reason". I haven't had time to read it and I suspect I would lack the technical know how to understand it completely, but from a summary I read it seems to give an interesting materialistic explanation to the "disembodied trips".


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