Response to Dr. Christof Koch

(An improved and updated version of this material has appeared in some of my academic papers. The version below is kept for legacy purposes.)

In a recent interview he gave to Skeptiko, neuroscientist Dr. Christof Koch has criticized comments I had made in an earlier Skeptiko interview. Here is my original statement, as played back to Dr. Koch during his interview:

The current paradigm says that conscious experience is an epi-phenomenon, or a by-product, or in any case generated by brain activity. So you should be able to always find a tight correlation between conscious states as reported by the subject and measurable brain states as measured, for instance, with an fMRI scanner. Usually this correlation is there, which indicates that there is a tight relationship between the brain and consciousness ... But there are instances, like this study that you alluded to in the U.K., where this correlation is not there in a very spectacular and repeatable way ... The only thing they could measure in the fMRI was a dampening down of brain activity in certain key areas. No excitation anywhere. Now, this breaks the correlation. The paradigm would require that an unfathomable experience, any experience what-so-ever, actually, should be correlated with brain activity and excitation of the brain, not a dampening down. That is a fundamental break with the paradigm as I see it. There is no way of escaping from this today.

The British study I refer to above was about the effects of psilocybin, the active ingredient of psychedelic mushrooms, on the brain. I discussed it in another article.

Now, here is Dr. Koch's criticism of my comments:

In general he assumes that consciousness involves excitation of the brain, but not dampening. That is a naive notion ... Let me tell you that's wrong, because otherwise you would have to argue that the epileptic brain, when the entire brain is hyper-synchronized and massively electrically discharged, would be hyper-conscious, because that's the maximum amount of activity ... but of course usually people during an epileptic seizure are unconscious. Consciousness arises out of complex interactions among [parts of] the brain. They can be excitatory or inhibitory ... [It doesn't have] to be all excitation or all inhibition. It's just a pattern of different neurons, some fire, some don't fire, and out of this differential pattern different conscious experiences emerge ... It's the differential pattern of activity [that matters].

Dr. Koch's chosen example – that of epileptic seizures – is irrelevant to the point in question. These seizures illustrate merely that brain excitation is not sufficient for subjective experience (hardly a surprise, otherwise we would be conscious of every autonomous process in our brains), while my claim was that brain excitation is necessary for subjective experience. The "differential pattern of activity" Dr. Koch alludes to aside, a subjective experience unaccompanied by an excitatory brain process would be a disembodied experience, which would clearly contradict the current paradigm of neuroscience. Dr. Koch acknowledges as much when he states, in the interview, that dream experiences "are caused by specific brain activity." This is a very simple point that shouldn't be lost in the contrivance of promissory explanations.

Dr. Koch suggested that my original statement reflected naive ignorance of the role that the interplay between inhibitory and excitatory brain processes plays in the rise of conscious experience. Therefore, although he stated that he had read my website, it seems that he missed a post where I explicitly elaborated on why I believe such interplay is not sufficient to explain the data. Be it as it may, it seems that Dr. Koch's point is the following: Even though the drug reduces brain activity as a whole, such reduction may be associated mostly with inhibitory processes in the "differential pattern of activity." Therefore, once the inhibitory processes are (partially) de-activated, excitatory processes may become conscious, which in turn causes the 'trips.' I can then imagine three scenarios:

First scenario: New excitatory processes could arise and grow due to the reduced inhibition. But these should then have been observed with the fMRI as deltas in the activation levels of certain brain areas, like e.g. the visual cortex, when compared to the placebo baseline. Such was not the case, as the researchers repeatedly emphasized in their paper. In fact, the researchers observed a further de-activation of higher-order visual areas.

Second scenario: 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 signature. 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 the second scenario, but let us pursue this a little further. Psilocybin '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, the second 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 discernible 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?

Third scenario: 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. Even if we leave aside the fact that postulating such an unknown mechanism is quite contrived, this third scenario still 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 paradigmatic assumption that experience is brain activity?

All this said, it is important to notice that my original claim does not rest on this one psilocybin study; after all, as intriguing and compelling as it may be, it is but one study. My claim rests on what I believe to be a broad pattern associating peak subjective experiences with generalized reductions of blood flow to the brain. Many techniques for the attainment of mystical experiences entail such reductions in blood flow. Hyper-ventilation and Holotropic Breathwork, for instance, induce psychedelic-like trances through constriction of blood vessels in the brain. Pilots fainting under G-LOC report Out of Body Experiences (OBEs). And, of course, Near Death Experiences (NDEs) entail a total cessation of blood flow to the brain. All are linked to structured, coherent, intense, and complex subjective narratives. To explain these narratives along the lines suggested by Dr. Koch would require that a reduction of blood flow to the brain as a whole somehow had a highly selective, detrimental impact on inhibitory processes alone, while somehow delivering a net metabolic benefit to excitatory processes. This evokes absurd images of hordes of 'Maxwell's demons' coordinating blood traffic in the brain to ensure that all blood still available finds its way precisely to excitatory neuronal networks, to the detriment of inhibitory neuronal networks.

In another part of his Skeptiko interview, Dr. Koch made the following comments about the possible physiological mechanisms behind NDEs and OBEs:

What happens in all of these cases, is the brain wakes up. It becomes unconscious, the blood flow goes out, then slowly the blood flow resumes ... and then different parts of the brain boot up at different times. It's not like there's zero activity; there is of course activity there. But it's differential activity. And so ... some parts of the brain are still offline, some parts of the brain are slowly getting online, the brain is trying to make sense of it and certain fractions of the time people report these intense experiences ... It's the activity in the brain that gives rise to these vivid experiences.

Basically, he is contending that structured, coherent, intense, and complex NDEs and OBEs can be explained by the progressive 'rebooting' of different brain structures as the brain wakes up. Therefore, what people like Dr. Eben Alexander report about their NDEs (see video above) is merely an artifact of the brain slowly coming on-line. If that is the case, I submit to Dr. Koch (somewhat tongue-in-cheek) that we may, right now, be waking up in some meta-reality, our entire lives here being merely artifacts of the progressive 'rebooting' of our meta-brains. Life as we know it, including all of neuroscience, may be merely a meta-delusion! Light-heartedness aside, Dr. Koch's presumed explanation requires – unless we selectively and arbitrarily dismiss certain aspects of what NDErs report – that a mere lack of synchronization in booting up different parts of the brain can create the illusion of a lifetime in a reality (at least) as complex and vivid as the one we ordinarily find ourselves in. I leave it to you to judge how reasonable a hypothesis this is, by comparing the short video above with Dr. Koch's explanation.

I have much respect for Dr. Christof Koch and applaud his continuing attempt to bring consciousness into the fold of scientific inquiry. I also fully understand that he, as the interviewee, had no obligation to prepare extensively for an interview. Yet, I do think that his dismissal of my original claim was casual. Further, as far as neuroscience is concerned, I am merely an educated layman. My Ph.D. was in computer engineering, the only neuroscience-related work I've ever done being a couple of years of research on artificial neuronal networks and machine intelligence. But then again, this should only make it easier and simpler for Dr. Koch to address my questions and criticisms above. I emailed these questions to Dr. Koch several days before this article was published, but as-of-yet I've got no reply. If Dr. Koch chooses to reply to this article, I'd be willing to publish his reply here with the same prominence of the present rebuttal.

The thoughts above may come across as complex because I wanted to be very explicit and specific in my analysis. But you should not allow that complexity to take your eyes away from the basic fact behind all this: Dreams and psychedelic experiences are similar in that neither can be attributed to sensory inputs. Yet, in a dream, when we do something as dull as clenching our dreamed-up hands, scientists can discern the corresponding brain activations with an fMRI image contrasted to the baseline brain activity. But when we have unfathomable psychedelic excursions into other universes, scientists see no brain activation whatsoever when contrasted to the baseline. That's it; it's just as simple. It's up to you to extract your own conclusions.