Islands of awareness

(Warning: neuroscience weeds)

An interesting paper by Tim Bayne, Anil Seth, and Marcello Massimi, which came up in my Twitter stream today, asks whether there can be islands of awareness.

Ordinary consciousness involves ongoing interaction with the environment, receiving sensory information, and producing motor output.  It has a functional role, enabling an organism to deal with novel situations, including dangers and opportunities.

However, it is possible, due to injury or pathology, for some or all of this interaction to be lost, for the consciousness to become isolated.  The authors start out discussing various medical situations where people can become almost completely disconnected on the output end, only able to communicate with the world by the twitching of an eyelid, or even worse, be completely locked in, unable to communicate at all.

It’s also possible to become disconnected on the input side.  Some of these cases are reversible, such as what happens in dreaming.  In that state, we’re generally disconnected from the outside world, although with a strong enough stimulus, that can usually quickly be reversed.  There is also the anesthesia drug ketamine, which apparently provides the same disconnection, but doesn’t always extinguish consciousness, sometimes leading to vivid and terrifying experiences.

But what the authors are most concerned about here are actual islands of awareness, where the system in question is completely isolated from the environment.  They explore three scenarios: ex cranio brains in a nutrient vat, hemispherotomy, and cerebral organoids.

An example of ex cranio brains were the disembodied pig brains which were kept alive in a nutrient delivery system.  The nutrient mix included a neural inhibitor to ensure that the brains wouldn’t regain consciousness, but suppose that inhibitor hadn’t been present?  Could such brains actually be conscious?  A lot of people would say no, that consciousness requires interaction with a body.  But if such a brain showed wide scale organized activity, it might “put pressure” on embodied cognition theories.

A hemispherotomy is sometimes performed on a patient with severe epileptic seizures.  It involves severing the connections between the damaged hemisphere and the other side, as well as its connections with the brainstem, thalamus, and other subcortical structures.  However, a hemispherotomy, unlike a hemispherectomy, leaves the tissue in place, with all of its vascular connections.

Could such a disconnected hemisphere be conscious?  The authors note that, under normal circumstances, without the activating signals coming up from the RAS (reticular activating system) in the brainstem, the activity in the disconnected tissue has very low firing rates, equivalent to a deep dreamless sleep.  But, they ask, what would happen if electrodes were inserted and used to stimulate the hemisphere?  Might it then regain some consciousness?

The authors discuss the role of subcortical regions in consciousness.  It’s well established that they provide crucial support, but what is the nature of that support?  Are they causal, constitutive, or both?  Causal means they just cause awareness in cortical tissue but don’t participate in generating or consuming the content.  Constitutive means they do.

Personally, I think with a disconnected thalamus, the question is somewhat moot.  Such a hemisphere’s ability to communicate with its disparate regions would be heavily compromised.  I tend to doubt any awareness is possible under those conditions.  Only if the subcortical connections were kept intact, with only the RAS disconnected, might it be possible to re-stimulate some form of consciousness.

The third scenario is cerebral organoids.  I did a post on these a few months ago.  The chances that any form of awareness exists in these largely random collection of neural cells is so close to zero that I find worrying about it counter-productive.  There’s simply nothing to indicate these small clumps of neural tissue are organized to have any sensory or affective functionality, and without that, it’s hard to call whatever is happening in them consciousness.  We might as well worry about whether brain tumors or other excised tissue are conscious.

The authors worry that as organoids continue to be developed, there may eventually be issues.  I guess that’s possible, but it only seems to be a significant possibility when enough of the various components of the brain start to be included, which still seems very remote.

The authors mention other possibilities, such as an in utero fetus with some pathology causing it to be completely disconnected.  Given how immature the brain is until well into the third trimester, this only becomes a possibility in the last few months of pregnancy, but it is a possibility.  Would such a system, with no history of sensory input, be conscious in anything like our understanding of the word?

But the most likely scenario is the ex cranio one, such as the pig brains.  It seems inevitable that someone will eventually try that experiment without the inhibitors.  What will it mean if the brains in that scenario do show wide scale organized activity?  The paper discusses the difficulty of detection in these scenarios, and of avoiding false positive and false negatives.

It’s worth noting that the major cognitive theories: global workspace (GWT), integrated information (IIT), and  higher order thought (HOT), are compatible with the ex cranio scenario.  But the more fragmented the tissue is, the less compatible these theories are, although IIT may posit even organoids as having some level of consciousness.  The theory that might be most compatible with small fragmentary islands is recurrent processing theory (RPT).

The paper finishes up by noting that neuroscientific progress increases the chances of producing these islands, and that they may already exist.  They call for careful consideration of the ethical issues involved.

What do you think?  Are conscious hemispheres or organoids more likely than I think?  Or are there solid reasons to conclude that disembodied cognition is impossible?

19 thoughts on “Islands of awareness

  1. I have no idea about organoids, but brains in vats are fascinating. Not just because that’s a classic of philosophical thought experiments, but it also raises the question about disembodied cognition. When philosophers talk about being able to leave the senses behind and dwell in pure thought, would it be like that? Would it be like anything we could conceive?

    Liked by 1 person

    1. It is hard to imagine, very hard. The closest thing may be the experience of a sensory deprivation tank, but even there the person typically has interoceptive inputs coming in, so they’re aware of their own breathing, etc. I can see why many people wonder if it would even be possible, although the various medical cases make me suspect that it would be.

      What’s even harder to imagine is the in utero scenario. It’s hard to see such a system as being conscious in any meaningful manner without at least a history of previous experiences to draw on for imagination.

      Liked by 1 person

  2. Interesting article. I think an active brain in a vat, has active brain states and therefore some conscious representations of those states. If they feel normal and nice, I wouldn’t know. Nice analogy with the brain tumor.

    Liked by 1 person

    1. Thanks. On feeling normal and nice, that’s the question. Would they be in some peaceful state, or some hellish one? Hard to know with our current knowledge. The good news is that without a body, any emotions or affective states would be less intense without the interoceptive loop. (At least that’s what’s reported about patients with severed spinal cords or other traumas.)


  3. Since I teach about awareness, your original question seemed nonsensical. Any awareness has boundaries, some we can extend and others we cannot. We can, through focusing out attention, limit our awareness to a subset of which we are capable. But we cannot, for example, extend our physical awareness of portions of the electromagnetic spectrum for which we have no sensors. Under no circumstances can we see or feel x-rays. We can feel the damaged done from being exposed to too many x-rays, but the x-rays themselves, no.

    In my sport archery, the initial training is with regard to what is to be paid attention and what is to be ignored. The muscles desired to draw a bow in the final stages are in our backs and we in general pay little attention to those unless they are strained or injured. Archers can, however, be trained to sense the level of tension in those back muscles, something that can be in anyone’s awareness, but typically is not.

    So, our awareness has boundaries which we can pull back and extend a little bit, but there are realms we cannot be aware of, simply because we have no way to sense them.

    So, I vote: Islands, Yes!


    1. Steve, on nonsensical, not sure which question you’re referring to. Certainly attention can focus awareness in specific areas, properties, or patterns. That’s not really what this was about, but whether brain tissue in isolation is capable of being aware. Or am I missing a connection between that and what you said?


  4. Fascinating post, although a bit morbid to my tastes. I remember reading an article in Scientific American back in 1968 (I think) about a monkey’s severed brain being kept alive in a vat of nutrients for over 24 hours and only terminated after determination that it could have been kept alive indefinitely. You commented “What’s even harder to imagine is the in utero scenario. It’s hard to see such a system as being conscious in any meaningful manner without at least a history of previous experiences to draw on for imagination”. Why shouldn’t a fetus’ brain in an advanced stage of development prior to birth have interoceptive experiences in utero (or even have audio experiences of voices and/or music or other sounds outside the uterus)? A newborn’s experience might be very disconcerting or frightening because he/she would have no experiential framework with which to make sense of visual (light/dark), audio (noise), tactile, etc inputs, And what about execution by guillotine? If consciousness continues for some time after decapitation, that form of punishment should be considered cruel and inhumane. The moral-ethical issues raised here become a singularity…

    Liked by 1 person

    1. Thanks Mike. I’m with you on the morbidity, although the sentience of disconnected brain tissue is something I’ve wondered about before. (When I learned that the RAS is necessary for the gamma wave level activity necessary for consciousness, it made me feel better.)

      I hadn’t heard about that monkey experiment before. I did once see something in a documentary on a very disturbing experiment where a monkey’s head was severed and reattached to another body. They couldn’t get the nerves reattached, just the vascular system. So the other body could keep it alive, but it had no control over it. In the video, the monkey was conscious but seemed horrified. (Could be me projecting, but it definitely didn’t seem calm.) Thankfully they didn’t keep it alive in that state for long. I think they’d have a hard time getting that experiment past IRBs today.

      I’m sure a fetus can have some experiences in the final weeks of pregnancy, although it’s reportedly limited since the utero environment keeps it in a mostly anesthetized state.

      On execution by guillotine, I did some reading on that several years ago. Supposedly, once the blood supply is cut off, the brain loses consciousness in seconds. What the experience of those final seconds is like, is not something that seems pleasant to contemplate, although with all the nerves severed, it might be largely numb and affectless.

      Liked by 1 person

    2. ” If consciousness continues for some time after decapitation, that form of punishment should be considered cruel and inhumane.”

      That’s an interesting perspective.

      Is it more humane to experience dying completely aware or completely unaware? Is there value in having that final experience of dying with awareness?

      I would opt for with awareness. In that case, it might be more humane than lethal injection.


  5. I think the brain, assuming undamaged, in a vat if stimulated in the right way would be conscious. Certainly I think the EM field theories would say so. Without memories I don’t know whether there would be consciousness of much, if anything. With memories, I would assume it would be in something like a dream/hallucinogenic state.

    Liked by 2 people

      1. With memories I think it would be much a like confused dream state. It might be a really bad dream state. Without memories, it might be like the oceanic feeling of the womb that Freud talked about in The Future of an Illusion.

        Liked by 1 person

      2. On second thought, you might have a phantom body like people have phantom limbs. Whether the body would hurt like phantom limbs might be an interesting question. You would probably descend into insanity after a little while.

        Liked by 1 person

  6. Perhaps in addition to sensory deprivation-like symptoms, a severed brain might experience affect-deprivation which might prevent the brain from maintaining homeostasis or receive feedback controls.

    Also, you mentioned that “a lot of people would say … that consciousness requires interaction with a body.” I would imagine that biologically-based consciousness would develop associations with various body parts and create a body mapping as it necessarily creates a world view; however, an AI-based consciousness in a robotic or software-based body could also develop different but possibly parallel associations and create adaptive system mapping and virtual or real world views.

    Liked by 1 person

    1. Affect deprivation is an interesting way of putting it. Based on what I’ve read about spinal cord injury patients, I suspect the brain would have affects, but less intense than normal.

      The brain definitely maintains a body map, at multiple levels, in the midbrain, but also a higher level one in the insula and somatosensory cortices. That map is constantly being updated in an ongoing interoceptive loop. With the loop interrupted, the maps wouldn’t have error correction. The results might be phantom pains as James mentioned, or maybe other phantom sensations.

      Liked by 1 person

    2. “sensory deprivation-like symptoms”

      Interesting aspect about this. Don’t know if you noted a paper or study that observed that people congenitally blind never become schizophrenic. But people with vision (obviously) or who lose their vision after birth can become schizophrenic. People trapped in caves or who voluntarily go through sensory (mostly visual) deprivation as in certain Tibetan practices will begin to have hallucinations at some point.

      So there is something particularly odd about visual processing and overall mental health.

      Liked by 3 people

      1. I hadn’t heard that about congenitally blind people not being subject to schizophrenia. Interesting.

        I did read a theory somewhere that schizophrenia may be the result of a misfiring error correcting system. We mostly see what we expect to see, what we predict is there, but in healthy people there’s an ongoing error correction process, which causes revisions in the expectations / predictions. This theory was that the error correction in schizophrenics might be hyperactive, making them prone to paranoia and hallucinations.


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