Consciousness and memory

Functional MRI brain image, showing areas of activation. Source: Wikipedia.
Often, when we wake up in the morning after a night of deep and uninterrupted sleep, a dark void of nothingness seems to stretch back to our last moments of awareness before falling asleep. Therefore, we very naturally conclude that we had absolutely no conscious experiences during the preceding few hours. Similarly, upon returning from general anaesthesia, we hold on to the comforting notion of having had no subjective experiences during the course of whatever medical procedure was performed on us. Yet, strictly speaking, all we can assert from our state of mind upon waking up is that we cannot recall any experiences during the preceding hours; not that experiences were absent. Unlikely as this may sound, for all we know we may have had spectacular dreams, lifetimes of rich perception and insight, but simply not remember a thing.

It is impossible for us to distinguish between the absence of a memory and the absence of a past experience. Indeed, states we ordinarily associate with unconsciousness are known to entail rich inner life. Our nightly dreams are just the most obvious example, but the list contains some very counter-intuitive ones. For instance, fainting caused by asphyxiation or other restrictions of blood flow to the brain is known to sometimes induce intense hallucinations and even full-blown mystical experiences of oneness and non-duality. The highly dangerous 'fainting game' played mainly by teenagers worldwide is an attempt to induce such experiences through strangulation, often at the risk of death. Erotic asphyxiation is a similar game played in combination with sexual intercourse.  The effect has been described as 'a lucid, semi-hallucinogenic state [which,] combined with orgasm, [is said to be] no less powerful than cocaine.' (George D. Shuman, 'Last Breath: A Sherry Moore Novel,' Simon & Schuster, 2007, p. 80) The technique of Holotropic Breathwork uses hyperventilation to achieve a similar effect: It constricts blood vessels in the brain, causing hypoxia. This, in turn, reportedly leads to significant transpersonal and mystical experiences.

Psychedelic substances have been known to induce similarly profound hallucinatory and mystical experiences. It has always been assumed that they do so by exciting the parts of the brain correlated to such experiences, thereby causing them. Yet, a very recent and as-of-yet unpublished study has shown that at least one particular psychedelic, psilocybin (the active component of magic mushrooms), actually does the opposite: It dampens the activity of key brain regions. Study leader Professor David Nutt: 'Our aim was to identify the precise areas inside the brain where the drug is active. We thought when we started that psilocybin would activate different parts of the brain. But we haven't found any activation anywhere. All we have found are reductions in blood flow.' Study volunteer Dr. Michael Mosley continued: 'A fall in blood flow suggests that brain activity has reduced. The areas affected were those parts of the brain that tell us who we are, where we are and what we are. When these areas were dampened down, I was no longer locked into my everyday constraints.' (see article published here) It seems that psychedelics too, like hypoxia, induce profound experiences through a deactivation of certain brain mechanisms.

If this idea is consistent, we should be able to take it a step further: Brain damage, through deactivating certain parts of the brain, should also induce profound mystical experiences under the right circumstances. Sure enough, this has been reported over and over again. Here are just two prominent examples: Dr. Jill Bolte Taylor's talk 'Stroke of Insight' and a more scientific study by Cosimo Urgesi et al. called 'The Spiritual Brain: Selective Cortical Lesions Modulate Human Self-Transcendence' (Neuron 65, February 11, 2010, pp. 309-319).

What one would normally expect to be associated to sexual arousal, intense hallucinations, or profound mystical experiences is precisely a hyper-activation of the brain; just the opposite of the dampening or deactivation actually observed. If the brain is the sole cause and generator of subjective experiences, how can a deactivation of the brain lead to the most intense experiences human beings have ever had? This very fundamentally contradicts the current paradigm of how conscious experience is produced. Yet, the growing abundance of evidence in this regard can no longer be ignored. Here is a quote from Dr. Pim van Lommel, a Dutch physician: "[D]uring stimulation [of the brain] with higher energy [electromagnetic fields], inhibition of local cortical functions occurs by extinction of their electrical and magnetic fields (personal communication Dr. Olaf Blanke, neurologist, Laboratory for Presurgical Epilepsy Evaluation and Functional Brain Mapping Laboratory, Department of Neurology, University Hospital of Geneva, Switzerland). Blanke recently described a patient with induced OBE [Out of Body Experience] by inhibition of cortical activity caused by more intense external electrical stimulation of neuronal networks in the gyrus angularis in a patient with epilepsy." (My italics) Interestingly, the angular gyrus is precisely one of the brain regions that the researchers behind the 2010 Neuron study, mentioned above, identified to be associated to feelings of self-transcendence when damaged during surgery. A tantalizing picture seems to be beginning to emerge in neuroscience.

An alternative model that explains all this, and remains entirely consistent with all neuroscience data yet produced, is the 'Mind at Large' hypothesis popularized by Aldous Huxley in the wake of his own psychedelic experiences. The origins of the hypothesis itself lie in the work of French philosopher Henri Bergson, particularly in chapter one of his book 'Matter and Memory,' and were then refined by Cambridge philosopher C. D. Broad. The idea consists in the following: The nervous system does not generate subjective experience, but rather filters it down. Conscious perception is thought to be a fundamental property of nature, irreducible to matter (a very valid idea to this day, in light of the 'hard problem of consciousness'). This way, every conscious entity is, in principle, capable of instantly experiencing all universal phenomena and truths, across space and time. The role of the nervous system is to restrict our perceptions to the space-time locus of the body, so to facilitate its survival. Our sense organs do not produce perceptions; they simply allow in perceptions that already exist in consciousness anyway, but which otherwise would be filtered out of awareness by the brain. Since the brain is thus a filtering mechanism that frames perception, interfering with its function through drugs or other methods naturally modulates our conscious experience to the extent that it disrupts the filtering process. It is thus no surprise at all that, as neuroscience has observed, states of the brain correlate well with subjective states of mind. But unlike current neuroscience, the 'Mind at Large' hypothesis can explain hypoxia- or brain-damage-induced experiences in a very direct and intuitive way: By deactivating parts of the filtering mechanisms of the brain, hypoxia and brain damage release consciousness from the grip of those filters and allow it to experience a broader reality.

If this hypothesis is true, as mounting evidence seems to suggest, we may have to revise our idea of 'unconsciousness.' Consciousness may never be absent. What we refer to as 'periods of unconsciousness' – be them related to sleep, general anaesthesia, or fainting  may need to be re-interpreted as periods in which memory formation is impaired. The very disruption of brain mechanisms induced by certain drugs or spiritual techniques may also impair our ability to construct coherent memories. Therefore, whatever unfathomable universes our consciousness may wander into during periods in which we are, from the point of view of an external observer, apparently unconscious, we may hardly be able to remember our experiences upon returning to an ordinary, analytical state of mind. Think of how elusive dreams can be: At the moment you wake up, you may still remember an early-morning dream; five seconds later, you already forgot it, but still remember that you had a dream; by the time you stand on your feet, you can't even remember that you dreamed at all. Anyone familiar with so-called 'mystical' experiences will know that similar elusiveness often applies to those unitary, non-dual states of mind as well. Memory formation seems to be highly dependent on our ability to conceptualize our experiences by framing them into an explanatory framework; that is, by telling ourselves in words what it is that we are experiencing. Only then do we remember things with clarity later on. Yet, when consciousness is partially released from the grip of the brain's filters, our ability to conceptualize our experiences is much reduced, be it because of cortical impairment or because of the trans-linguistic nature of the experiences themselves. Either way, the net effect is the later impression that nothing at all has happened! How much of our lives do we forget in this way?

Contemplating the unfathomably broader reality perceivable upon a partial or temporary release from the brain's filters, and then being able to remember enough of it to articulate something to others, may require a very delicate balance: Enough deactivation of the right brain mechanisms should be achieved, but sufficient function in the right cortical regions should be preserved to allow conceptualization and memory formation. Staying on this thin borderline is difficult; drift too much to one side, and one experiences nothing; drift too much to the other side, and one remembers nothing (or, worse, one doesn't return). The elusiveness of such balance may explain why our culture has been locked into a naive and myopic materialistic paradigm for so long. Unlike so-called 'primitive' societies, we no longer subject our bodies to the physical extremes – like strenuous effort, malnutrition, weather exposure, isolation, or untreated chronic illness  which would have impaired brain function just enough to give us a glimpse into the 'other side.' We no longer subject our youth to the ordeals and rites of initiation that would have reminded them of the true nature of reality. So the longer and more comfortably we live, the more we forget that there is something else.

Don't get me wrong: That we live in better health, comfort, and have become enlightened enough to spare our children unnecessary stress are, certainly, good things. But a side-effect of it is that we've firmly planted ourselves in one side of the divide between life and death; between filtered and unfiltered consciousness. We have lost access to the 'otherworld.' We have lost our ancient ability to occasionally cross the boundary and come back to tell the tribe our tale. Indeed, for most of us, the only time we step on that elusive borderline are our short departing moments from this Earth. Then, for the first and last time since early childhood, we may see reality unfiltered, and yet retain enough brain function to remember and articulate what we see. But the window of time to communicate anything coherent is too short for our utterances to be taken seriously. Moreover, once standing on that promontory of freedom at last, we are probably too overwhelmed by vast vistas to even bother trying to speak. The only possible reaction to the experience might indeed be a total surrender to awe, as Steve Jobs so simply, yet powerfully, captured in his now famous last words: 'OH WOW. OH WOW. OH WOW.'

Could anyone have said anything more appropriate?

Important disclaimer: Any activity that (temporarily) impairs brain function, be it through intoxication, hypoxia, or any other stress-inducing mechanism, is potentially dangerous and even life-threatening. In my view, some  like chocking or ordeals – should simply never be attempted by anyone. Even apparently harmless techniques, like meditation, can have negative side-effects like mild dissociation and relaxation-induced anxiety. Extensive research, judicious preparation, and preferably professional supervision should precede and accompany the use of any of these techniques. Conservatism is advisable. Some techniques, like the use of psychedelics, are unlawful in most jurisdictions and carry severe penalties.

Copyright © 2011 by Bernardo Kastrup. All rights are reserved.


  1. Wow... awesome article... pulling together these various examples of stepped-down brain activity and the associated states of expanded consciousness is a terrific connection.

  2. A very interesting article indeed! I write about the notion that the brain might act as a kind of "filter" at the following link:


    You might enjoy this description of religion/sex/asphyxia....

  4. ever heard about neural inhibition and excitation?

    1. *yawn*
      Type "Novella" or "Koch" in the search bar of this blog to see my online exchanges with neurologist Dr. Steven Novella and neuroscientist Dr. Christoph Koch on this very point, which I have explored ad nauseum in multiple occasions.

  5. But what is "memory", from an idealist perspective? I argue that memory is a non-local phenomenon. In the way that even if all the processes related to human existence are bound to the physical image of our body, memory isn't. My personal view is that memory constitutes a "direct upload" into the Mind at Large, but we are restricted to accessing just a limited segment of it, just like a personal account on a cloud storage.

    One of the main reasons why I argue this is the case is because all the processes within our "whirlpool" are represented by physical processes, and the storage processes of memories are yet to be found. From all the clinical experiments and observations, it looks like "accessing" the memory is all that was observed. For example, the way people with Alzheimer recall memories previously lost when a neural pathway is recovered.

    So, what happens when we cannot recall an experience? Does it fail to "upload"? Or it is uploaded, but we fail to access it?


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