Conciousness and cutting a brain in half, what would happen? - Page 2

tdvance · #31 (**permalink**) 22-March-2008, 03:49 PM

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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Originally Posted by Fazor

Well, technically since the areas of your brain that control vital operations of your body not on both hemispheres, likely both bodies would be dead.

I know, that's no fun.

Consiousness, best I can tell, is really just a collection of different sensations brought about by various senses. Or, as others have said with less words and more clarity; it's not a single thing, but a collection of things. Therefore, if you did manage to "split brain" transplant into an empty body, you'd have two un-shared consiousnesses, though they'd each be made up of whatever senosory abilities they ended up with.

To look at it another way, say each half devlopes into a fully-functional brain. Now you're still standing next to the other body. You experience the pain from the surgery to open your skull. You smell the aneseptic smell of a hospital room. And you see your friend Bill looking at you with his one un-decomposed eye.

Bill feels the pain from his skull being opened (and from the various body parts that decomposed partially until you generously donated your brain). He feels a draft, because the nurses forgot to tie closed his hospital gown. He smells the aneseptic smell of the hospital room, but also the gas he just passed that hasn't wafted your way quite yet. And he sees you, looking at him with an expression of pure horror as you realize you just brought a zombie to life.

There you have two completely seperate consiousnesses. Now you may ask if you two will "think alike"...but our ability to reason is learned, and based off our life experiences. Assuming those were transfered aswell, then yes, at first you'd probably think pretty much alike...but personalities would diverge based on the experiences you have after the split.

That's my best stab at it, but I'm not a doctor (and I don't play one on tv!)...so take it for what it's worth.

grant hutchison · #32 (**permalink**) 22-March-2008, 03:50 PM

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Originally Posted by FriedPhoton

I'm going to disagree with this based upon my belief that consciousness is self-awareness. We understand our self to be that which we feel is connected to us and providing feedback via our nervous system. Inside our heads it's dark and there is no way to perceive anything aside from perhaps a lack of oxygen or chemical imbalance, but even those things we understand as happening to ourselves because we can detect the change. And the rest of our senses we understand are a part of self because we perceive the stimulus they send our brain. I do not look at my neighbor's eye and wonder if her eye is a part of me. I know it isn't because I do not perceive input coming from it. There is a clear distinction between myself and other people, the boundary of which is the extent of my nervous system. A sense of self is about as real as anything in the world. No rationalization is required.

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

tdvance · #33 (**permalink**) 22-March-2008, 03:51 PM

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Originally Posted by Ross PK81

So I guess, If every human being on earth had their brains connected to each other, we'd just be 'one' conciousness. I wonder if it'd feel any different? Would that one conciousness be way way way more aware of reality than what any one single person is? It's got to if it would lessen with a brain continually being cut into half.

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.

grant hutchison · #34 (**permalink**) 22-March-2008, 03:56 PM

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Originally Posted by Joe Durnavich

Which of the following would indicate to us that their selfhood was reasonably intact?

(1) They insist that it is.

(2) Their behavior is pretty much the same after the operation as it was before it.

(1 is actually encompassed by 2, but the general idea here is that 2 clearly has criteria on which to base a judgment.)

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

grant hutchison · #35 (**permalink**) 22-March-2008, 03:59 PM

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Originally Posted by Disinfo Agent

Quote:

Originally Posted by grant hutchison

Yes, it's that sense of continuity which convinces us that we are a single, continously existing "self". It's remarkable the insults that selfhood can withstand. I can fill you with barbiturates until your EEG is a flat line punctuated by uncoordinated bursts of electrical activity, and keep you that way for days; I can shoot you in the frontal lobes; I can remove half your cerebrum; I can chill you into hypothermia and stop your heart for half an hour; I can pass a current through your brain so that your whole cortex lights up with uncoordinated electrical activity: and yet you still reboot with a sense that you are the same person who existed before the disruption of processing.

You -- you get away from me, you!

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

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

Grant Hutchison

trinitree88 · #36 (**permalink**) 22-March-2008, 05:51 PM

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

pete

TrAI · #37 (**permalink**) 22-March-2008, 08:03 PM

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...

Disinfo Agent · #38 (**permalink**) 22-March-2008, 08:48 PM

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

grant hutchison · #39 (**permalink**) 22-March-2008, 10:49 PM

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Originally Posted by TrAI

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?

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

FriedPhoton · #40 (**permalink**) 23-March-2008, 03:52 AM

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.

Ken G · #41 (**permalink**) 23-March-2008, 02:37 PM

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Originally Posted by grant hutchison

and yet you still reboot with a sense that you are the same person who existed before the disruption of processing.

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".

ASEI · #42 (**permalink**) 23-March-2008, 02:46 PM

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and yet you still reboot with a sense that you are the same person who existed before the disruption of processing.

- 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.

grant hutchison · #43 (**permalink**) 23-March-2008, 03:25 PM

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Originally Posted by Ken G

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?

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

Joe Durnavich · #44 (**permalink**) 23-March-2008, 04:22 PM

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Originally Posted by grant hutchison

but most of us are lucky enough to retain a sense of being one continuous self during the whole process of maturation and senescence.

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.

Joe Durnavich · #45 (**permalink**) 23-March-2008, 04:35 PM

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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.

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.

grant hutchison · #46 (**permalink**) 23-March-2008, 04:53 PM

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Originally Posted by Joe Durnavich

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?

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

Joe Durnavich · #47 (**permalink**) 23-March-2008, 04:54 PM

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Originally Posted by Ken G

I've often suspected that our sense of identity is manufactured...

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.

grant hutchison · #48 (**permalink**) 23-March-2008, 05:00 PM

Quote:

Originally Posted by Joe Durnavich

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 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.

Quote:

Originally Posted by Joe Durnavich

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.

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