I don't have a reference, but I recall a split-brain experiment in which the person's right brain actually learned to speak (so the man could answer what he saw on his left side too). The two halves of the brain went on to develop (slightly) different personalities. Other split-brain patients said they felt as if half their body had "a mind of its own"--so for example, one could deduce, and speak, that a dinner plate was to the left because, he said, he could hear it rattle when he saw his left hand reach for it, though he said he didn't consciously reach for the plate. From his left brain's point of view, it just happened. I read this in Penrose's "The Emperor's New Mind" but I forgot which studies he was summarizing.

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Todd (Bowie, MD, US, North America, Earth, Sol System, Vega region, Local Bubble, Orion arm, Milky Way Galaxy, Local Group, Virgo A Cluster, Virgo supercluster, the universe in which spock is clean shaven)

Quidquid latine dictum sit, altum sonatur.

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This is an aspect of selfhood which is rather different from the sense of being a continuously existing consciousness: it relates to ownership of one's own body, rather than continuity of conscious existence. It is possible to have one without the other. There are, for instance, people who deny that their own limbs are their own: a patient may be frightened to discover a left arm attached to his body which he does not recognize as being his own, for instance. And yet that person will be aware of his own continuous existence as a person, in continuity before and after the stroke that has led to his current predicament.

Grant Hutchison

That's an interesting question, as no split brain has ever been reconnected. I imagine there would be conflict at first, as both halves learned to speak different "languages", or dialects at least. Take two or more brains that never were part of the same brain, it could only be worse. Would they eventually merge into a single consciousness? Maybe, eventually.

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Todd (Bowie, MD, US, North America, Earth, Sol System, Vega region, Local Bubble, Orion arm, Milky Way Galaxy, Local Group, Virgo A Cluster, Virgo supercluster, the universe in which spock is clean shaven)

Quidquid latine dictum sit, altum sonatur.

personal page: http://blog.astrosketches.info

Like HenrikOlsen, I believe the topic under consideration from the OP is a sense of continuity of self, before and after surgery. So 1) is the only test. Our patients may fail 2) for all sorts of reasons. Indeed, we all fail 2), over the course of our lives, by changing our behaviour in many different ways; but most of us are lucky enough to retain a sense of being one continuous self during the whole process of maturation and senescence.

Grant Hutchison

I've done some of these things.
But not others.

Now, where did I put that fine Chianti ... ?

Grant Hutchison

...and of course it opens up the possibility of an Out-of-Two Bodies experience...OOTBE. pete

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Hmmm... I was reading that thing about the functional hemispherectomy thingy... Does that mean that in stead of totaly removing the parts of the brain they are simply cutting the neural connections between that part and the rest of the brain/nervous system, but leaves it connected to the bloodsupply?

If so, wouldn't that mean that that part now contains a copy of the person that is totaly cut of from the rest of the body? How do one explain that possibility to some little child?

I mean, it would be rather terrible to wake up from the surgery only to find that you are totaly cut off from your body...

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Here's an interview about this: Left-brain, right-brain, split-brain.

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In functional hemispherectomy, there is a commissurotomy, severing direct communication between the two halves of the cerebrum, and also some removal of brain tissue from one side of the brain. So it's a halfway house between a split-brain procedure and a hemispherectomy.
A split-brain procedure separates the functions of consciousness, but doesn't cut either bit of brain off from the rest of the body: each half of the cortex has input and output to its own half of the body, together with considerable cross-over. The two sides of the cerebrum also maintain contact with each other through lower centres, as well as by observing what the other half is doing through the senses. So a person with a split brain behaves under most circumstances like an individual with a single consciousness. Experimenters have to use quite elaborate measures to "isolate" the two sides of the brain in order to demonstrate their different behaviours.

Grant Hutchison

I listened to a podcast on epilepsy today. The speaker talked about the need to perform an hemispherectomy on a patient. The patient's insurance company replied to a request for approval by stating that they would pay for the procedure, but only once.

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What seems to me the natural explanation for this is that we create, in the current moment, this sense of continuity as part of the mechanism whereby we manufacture a sense of self. Is there any evidence that a continuity is actually required in some sense, or is it just memory that is needed? And in the absence of memory, would that be manufactured too? I've often suspected that our sense of identity is manufactured, and that consciousness is more like a single thing, as if we all share effectively the same one but compartmentalize it to "fit" in each brain separately. Presumably the compartmentalization provides survival advantage to each "compartment".

- now that you mention it, every night when you go to bed, your conciousness "discontinues". You don't fear it like you do death because it doesn't impair your functioning as an organism. Every morning, "you" restart and go about your business.

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If continuity is required, then it is some very deep process, down in the brainstem: my little list of catastrophic brain events was intended to show that you can mess with the cerebral function very dramatically without losing the sense of a continuous self.
So it is indeed as if you have a brain mechanism which goes looking for "autobiographical memory", and then aligns your current self in continuity with what it finds. It seems to be pretty robust, since people with global amnesia still have a sense of being a single self, as do people who have lost the ability to lay down new memories, as do people who have suffered an episode of unconsciousness lasting for months or years.
But it can also be disrupted in various ways: psychiatric illness and drugs prominent among those. I've experienced depersonalization for a couple of hours myself (sleep deprivation and stress, in my case), and it's not an experience I'd recommend.

Grant Hutchison

To me "sense of being one continuous self" sounds, well, New Age. Perhaps answering this may help me understand what you are talking about: Is it possible to have a "sense of being a discontinuous self"? If so, why might a person think his or her self is disrupted?

Another way of looking at this is that the way everybody talks about this subject, it sounds like if you ask anyone if their self is continuous, and they are functionally able to answer, they will always answer "yes." Without clear examples of disrupted self, it is hard to see that the notion of continuous self is meaningful except in a rhetorical or poetic way.

This would fall under my option (2) in that your behavior is different in the sense that the manner in which you conduct your life has been disrupted. You felt depersonalized because you lost control over your life, etc.

I think if "self" refers to anything, it refers to your life in the world and not just to some inner brain state or whatever. In that scenario, disruptions to self are disruptions to your life, which consists of both you, your environment, and what you can achieve in it.

I've given some causes above: psychiatric illness, drugs, sleep deprivation, stress.
In my own experience, I simply came unstuck from the person I knew to be Grant Hutchison. "He" was walking fast in the middle of the night down a very long country track in the pouring rain, and "I" realized that I had no influence over what he was doing. I felt it was quite important that he stop walking for a while, but it was evident to me that he had no intention of doing so. I spent a bit of time inside his head, and a bit of time trailing behind him, like some sort of fretful disembodied kite. My self had bifurcated.

Others describe losing themselves entirely, of feeling like an automaton who inhabits the body of the person they remember having been, but who doesn't exist any more.
And most people, at one time or another, have had the transient sensation of being a mere spectator in their own heads, of observing themselves do or say things that they don't feel they have initiated.

Once you look at the neurological correlates of consciousness, and see how they flit around, it seems surprising that this sort of thing doesn't happen more often. It seems remarkable that such a congeries of scattered neural events can ever generate an "I" who persists in time.

Grant Hutchison

It is lived, not manufactured. There are myriad things you do and that happen to you that constitutes having a sense of identity. You answer to "Ken", the people you are in contact with treat you in particular ways, you go to the same job every day fulfilling the same position, you come home to the same family, you file taxes under a particular Social Security number, etc.

There is no way to identify them all, hence, the notion of a sense of identity can seem mysterious. We tend to feel that there has to be a single referent for the term, so we assume that there is some distinct "feeling" or "sense" in the head.

I hope the further detail above shows how that's not the case. I think you're perhaps using "depersonalized" in a pop-psych sort of way, when it's used to designate any sort of uncomfortable feeling induced by loss of autonomy or dignity.

You are of course welcome to define "self" in this way, which looks like it's a behaviourist approach to the matter. In effect you're denying the validity (or perhaps the usefulness) of any internal experience I (or others) report to you.

Grant Hutchison

Grant, it sounds to me like your sense of self was intact, but your body's behavior puzzled you. Is that considered a disrupted self?

Not at all. My purpose is not to deny, but to expand and widen the context of things considered in discussions like these. A lot of things we consider internal, like a fear of failing a test, for example, are not entirely internal; they also encompass stuff that is happening, has happened, or will happen in our lives. The "fear" is best seen in the wider context.

Wow Ken, I'm kind of surprised to hear these comments coming from you. Based upon my past experience reading your posts this seems totally out of character. I must be misunderstanding your meaning. I don't understand what you mean by consciousness being a single thing that we share. Could you clarify that for me?

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My sense of self was not intact, since I no longer felt myself to be in continuity with "Grant Hutchison".
That's the common theme for people who describe depersonalized episodes; that they have lost continuity with their "former self". Either that self has ceased to exist, or they have come unstuck from it.

You can of course consider things in this way, but I fear you're trying to find a place in the external, objective world for something that is the quintessence of internal, subjective experience.

Grant Hutchison

As I stated before, I believe that consciousness is self-awareness. I think it is important to note that while you are sleeping you are still self-aware but on a diminished level. Your brain still processes sensory input and depending on how deeply you sleep various alarm triggers may or may bring you to full self-awareness quickly. If you damage the brain or impede it in some fashion you can remove consciousness by removing awareness of self (or the ability to process sensory input to a degree necessary to maintain consciousness). If the cause is irreparable damage then it is highly unlikely consciousness will be restored but if it is due to something like drugs, a temporary lack of oxygen, or something poisonous, then removing the problem before damage is done will restore consciousness.

I also believe that consciousness is an emergent property of a very complex system, and as such does not require all of the parts, just enough for the property to emerge. There is also the possibility that there are multiple emergent properties hierarchically arranged that lead to even more complex emergent properties. I think the fact that we are built of innumerous networks of smaller complex systems starting with the arrangement of atoms, to proteins, nucleic acids, and so on, up to cells, tissues, organs, and ultimately a complete being, proves out the idea of this hierarchy. To understand consciousness it is possible we'll have to understand the emergent properties of each system in the hierarchy and how those properties interrelate.

A benefit of this complex system is that you can remove parts and/or replace parts without disturbing the whole since the emergent properties depend upon the quantity of the elements that bring it about. Below some threshold the property will no longer exist, but above it you may be able to continuously add up to some reasonable limit without losing the property once again. Between those limits the property exists and adding or removing quantities of the elements that make it up do not disturb it.

In a hierarchical system the same is probably true of the lower level emergent properties supporting the higher level emergent properties.

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One of the most important functions of the brain is its predictive abilities. What I mean by this is that through experience we come to expect the world to operate in a certain way. We have learned what to expect. When I want a drink of my coffee I must be able to conceive of the idea that sometime in the near future my hand will be able to grasp the cup and bring it to my mouth. As my hand reaches for the cup I'm continuously making predictions about what movements I need to make to get my hand to it. The same can be said for how much pressure I need to apply and whether or not I should grab the cup by the handle or can grab it whole. Then I apply a known amount of force to lift it and follow the same continuous careful adjustments to move the cup as I continuously predict where it must go.

This is just a small example but anyone could easily extrapolate this to everything we do. Our brains spend a great deal of their effort predicting the future based upon what has been learned in the past.

If my predictive ability becomes distorted I will be disturbed. My ability to predict is a fair measure of my intelligence. If I can predict I am conscious, if I can't I am not. When someone lies to us it impairs our ability to predict accurately, so we do not like it.

If some alteration to my brain, either temporary or permanent, impairs my ability to predict I will be seen as having a mental illness. In some cases, such as poisoning the brain with alcohol, we know the effect is temporary so we do not send a person to the doctor for an intervention. But if a person acted drunk all the time we would. Regardless, we know that the person, at the time of the impairment, has poor judgment and requires extra attention to prevent them from hurting themselves.

Psychology and psychiatry may be better served by focusing on people's predictive abilities explicitly. If all aberrations are seen as an inability to predict properly there would be a more unified approach to the science.

Unfortunately my own predictive ability is currently impaired by stress, knowing I have things to do that are distracting me, and I can not bring these individual examples to a cohesive point, so I will have to leave it to the reader to predict where I might have been trying to go with all this.

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Arthur C. Clarke

The Brain Science Podcast

It's interesting to contrast that kind of depersonalization, which does seem like a "mistake" when you find it connected with an overworked and undersupplied brain, with both a more "normal" construction of your persona, and with the construction you generate when "in the zone" of some activity that has you completely focused with a fully functional and well-supplied brain. I think we construct many personae when in different situations, which we try to thread together into some loose sense of "who we are" that at the end of the day might not have a whole lot of coherent meaning. I often think about how I acted in certain situations, and just shake my head and say "who was that guy?" I don't recognize him from a complete stranger, but I have to allow that it is the person I become whenever in that situation. Thus it follows that if I simply include in "that situation" the complete context of someone else's DNA and memories, then that is literally the person I become "in that situation" as well. Ergo, a "continuity of consciousness" is nothing other than a "continuity of situation".

That may be the most insightful observation on consciousness I've ever heard. The challenge to the evolutionary biologist is then-- find the survival advantage, or admit that consciousness is a "spandrel" of intelligence.

I would say that all of those things come closer to the way other people construct my identity, and the pressures I feel as a result. The identity I perceive is not directly related to any of those-- though they may in some sense help feed the process, whatever that process really is. Those are the things that I value and am committed to, so I would not walk away from them, but my identity would allow me to do so if I was strongly enough compelled.

I think that's right, and it makes sense at a neuroscientific level, when we see activity in various parts of the brain surging and fading as we perform different tasks and experience different emotions. We have a sort of mean activity that we associate with our normal behaviour, but that doesn't prevent personality traits shifting a little (or a lot) under particular stimuli. Most people would identify with the notion that they have at least a slightly different personality in the presence of strangers than when among friends, or when with their parents.
In the longer term, the personalities I had as a child, as a teenager, as a young adult, are very different from my average set-point at present; again, I think most people would identify with that.

The odd thing is the phenomenon you describe, of looking back and thinking "Who was that guy?", while nevertheless being absolutely sure it was you. People acknowledge this when they say things like "I don't know what came over me" or "I just wasn't in my right mind": there is always a core "I" in there, buffeted but undisrupted.

Grant Hutchison

I haven't much idea what consciousness is, but if I had to guess based on limited information, I would guess that it is an entity of some kind that leaves an organized footprint on what is objectively observable, and leaves an imprint on subjective perception that we can only know by experiencing it. The scientist studies the former imprint. But I don't see that "we each have our own" version of this entity, any more than each lake has its own version of water. There certainly may be objective differences in depth, temperature, salination, etc., but none of those things are what make it "water" in the first place. And like that water, it has a way of moving around from lake to lake. So the "identity of water" would be kind of an illusion generated by each "lake", if one wants to really stretch the analogy. It's the best I can do.

If it sounds somewhat New-Agey, and that's what you mean by being out of character, I think this is because I never view science as the sole or best means of knowing about everything. Some things may actually be easier to know subjectively than objectively-- like what depersonalization feels like (or a waterfalls on your head on a hot day in the tropics, to pick a more positive image).

There is some clear connection between intelligence and consciousness, but I'm not sure it is this cut-and-dried. I see ability to predict as closer to intelligence than consciousness. One question would be, was Grant less conscious when he couldn't predict his own behavior? Since he appears to remember exercising higher-level consciousness in the thoughts he recalls experiencing at that time, it seems he was conscious then. So the processes that "generate" consciousness may not be the same as those that generate intelligence-- if the former is even an "emergent" or "generated" process at all (the latter seems more clearly to be so). If you turn a glass upside down, all the water flows out-- but water is still not an "emergent property" of a glass. A working brain could be a vessel for consciousness as much as a generator of it, we simply don't know.