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Brain hemisphere separation
March 12, 2005 6:03 PM   Subscribe

Is it possible to safely separate the hemispheres of the brain? If so, can I ever have such a surgery done?
posted by jimmy to Health & Fitness (22 answers total) 1 user marked this as a favorite
 
The word 'safely' is subjective, but supposedly it's been done. This Q&A also suggests it has been done, and that there is only minor benefit. The cons are not covered, as far as I can tell. Do note that both pieces refer to the same doctor, so tread with caution.
posted by wackybrit at 6:26 PM on March 12, 2005


Yes, if by that you mean the partial or complete removal of the corpus callosum (corpus callosotomy), the fibre bundle that joins the two hemispheres of the brain. This is sometimes done to deal with otherwise untreatable forms of epilepsy.
posted by SPrintF at 6:26 PM on March 12, 2005


Corpus Callostomy. So yes, but I think it's a procedure of last resort.
posted by PinkStainlessTail at 6:27 PM on March 12, 2005


I'm not sure how safe the surgery is, but it has been done. In the past it was a treatment for epilepsy. It had strange psychological effects, such as a person losing control over his the right side of his or her body. That side appeared to have its own mind, at times at odds with the desires of the other side (see Oliver Sack's The Man Who Mistook His Wife For a Hat).

The procedure severs the corpus callossum, so it is generally called a cerebral commissurotomy if you want to search for effects yourself. I don't believe it is reliable in treating any known symptoms.
posted by ontic at 6:28 PM on March 12, 2005


Ok, I didn't realize it was still used. I'd trust those links above.
posted by ontic at 6:30 PM on March 12, 2005


Yes, (see SPrintF's answer). Note that this inhibits (but does not entirely suppress) coordination between the two hemispheres -- some researchers have even claimed to see evidence of a separate consciousness in each hemisphere after surgery.

However, absent a generalized epilepsy that could not otherwise be controlled, no doctor could ethically perform such surgery on you.

Out of curiosity, why would you want such surgery? If it's purely out of a desire to "see what would happen", you should know that it's possible to get a similar (although not quite the same) effect by temporarily sedating one hemisphere and not the other -- this is done prior to certain brain surgeries, to detect an individual's language dominant side of the brain, among other things. This can be done relatively safely by injection of sedative into one of the two carotid arteries, and has no long-term effects. It's remotely possible you could talk a researcher into doing this for you as part of an ongoing research programme.
posted by orthogonality at 6:34 PM on March 12, 2005


[On preview: I take too long.]

Yes. This used to be done for epileptic patients that didn't respond to various forms of drug therapy. The idea was that the "echos" of epilepsy would be mitigated if you cut the room in half. See this.

There are a number of interesting effects of having a split brain. First of all, one's right brain controls the left half of the body, and vice versa. So if you see something out of your right eye, only your left hand will be able to point to it. Also, only your left brain can talk (this seems sketchy, but I think this is still true) - so you can only report on what your left brain has seen and knows.
This has more, and here's a student's paper, another and the home of the first site here.

Why on earth would you want to have such surgery done?
posted by metaculpa at 6:34 PM on March 12, 2005


Why on earth would you want to have such surgery done?

basically to experience the things you described, but I guess orthonogality's method sounds a bit safer.
posted by jimmy at 6:50 PM on March 12, 2005


The answer to your second question might be "no", anyway; I doubt you could just go out and have brain surgery done on yourself.
posted by kenko at 8:10 PM on March 12, 2005


Yes, the surgery is safe in that it's been done without harming the patient. No, you probably won't convince any doctors to perform the surgery because it's unlikely that you have the need to have the operation.

On an aside:
During my psychology 101 class we watched a video testing people who had undergone this surgery. The one test i remember being very interesting is that each person was given several objects to feel that they couldn't see. They were then shown an object (on a screen) and asked to identify (through feeling) an object that associated with the item on the screen. For example, on the screen was shown a cigarette. One of the objects they could feel was an ash tray; they were supposed to match these up. People who had this brain-splitting surgery were completely unable to match these items up correctly. It seems as though the feeling portion and the grouping portion of the brain are on different hemispheres and by separating the communication in the brain, problems like this arise.

Some more info on this here and here.
posted by escher at 8:42 PM on March 12, 2005


I've always wanted to experience what it would be like to have a split brain, and I once tried idly searching around to see if there were a way to safely have it done. No luck. It's not a recreational thing.
posted by painquale at 10:18 PM on March 12, 2005


othogonality: "some researchers have even claimed to see evidence of a separate consciousness in each hemisphere after surgery"

Seems likely, since people can survive and (to an extent) recover from a stroke which kills an entire hemisphere.
Reminds me of a rhetorical question posed in a lecture - since a person can continue with their life with just one hemisphere, who would you be if each hemisphere was transplaneted to a different body? What becomes of your concept of personal identity?

Ouch. :-)

And your suggestion of local sedatives is a far FAR better approach than what sounds uncomfortably close to self mutilation.
posted by -harlequin- at 11:26 PM on March 12, 2005


There is also a famous case about a young child (under 10) with eplileptic seizures so bad, that they had to remove an entire hemisphere of her brain. This cured her epilepsy, and since she was so young, her brain was able to sort itself out, and she is now a fully functioning intelligent adult. (Rumor has it that if she shakes her head vigorously, she can feel her brain move... but my prof might have been pulling my leg about that part. The rest is true though.)
posted by ruwan at 12:03 AM on March 13, 2005


Callosotomy and commisurotomy are not the same thing. Most modern callosotomies are anterior only, reflecting the fact that they are used to prevent contra-hemispheric spread of neocortical epilepsies, which by far originate in the frontal and anterior temporal lobes. Posterior callosotomy creates unusual and quite disabling visual anomalies, including sometimes alexia without agraphia (the inability to read combined with unaffected writing skills.)

Hemispherectomy is usually done only in children younger than age 5, again for intractible unilateral epilepsy. The remaining hemisphere often gains some rudimentary control over the ipsilateral side of the body which was previously controlled by the removed hemisphere.

The Wada test, injection of amobarbital into 1 carotid artery, is done to assess for cerebral dominance with respect to things such as language and memory. The procedure is usually harmless and without long term effects, but carries a 1% risk of stroke and a non-zero risk of carotid dissection.

Bottom line: these are dangerous and occasionally crippling procedures, done in the hope of relieving persons of the terrible burden of hundreds of uncontrollable seizures per day. They are not parlor tricks or games and will not be done to healthy people by any ethical practitioner.
posted by ikkyu2 at 4:21 AM on March 13, 2005


In The Emperor's New Clothes, Roger Penrose briefly muses on the possibility of severing the corpus callosum temporarily, and reconnecting it.

What would it be like to have the experience of being two individuals, and then one again? Interesting question.
posted by Leon at 5:15 AM on March 13, 2005


geez ikkyu2, what a buzz kill. We're all like, "Ohh, let's chop our brains up 'n stuff!" and then you're all like "It's dangerous and wrong!"

stupid doctors and their stupid ethics.
posted by leotrotsky at 6:55 AM on March 13, 2005


basically to experience the things you described

Eh, just go read The Origin of Consciousness in the Breakdown of the Bicameral Mind, A Scanner Darkly, and some Sacks; experience it vicariously. Err....unless reading one of those things is why you want to do this for real... Regardless, awesome question.
posted by jbrjake at 8:28 AM on March 13, 2005


orthogonality writes "This can be done relatively safely by injection of sedative into one of the two carotid arteries, and has no long-term effects. It's remotely possible you could talk a researcher into doing this for you as part of an ongoing research programme."

ikkyu2 writes "The Wada test, injection of amobarbital into 1 carotid artery, is done to assess for cerebral dominance with respect to things such as language and memory. The procedure is usually harmless and without long term effects, but carries a 1% risk of stroke and a non-zero risk of carotid dissection."

Um... not so good.

Thanks for the correction.
posted by orthogonality at 9:51 AM on March 13, 2005


Bother! I am failing to Google up the Roger Zelazny short story with a assassination-trained right-brain (and left hand) foiled by a law-abiding left-brain (and right hand). This special assassin is manufactured in order to fool Secret Service telepaths. Not a particularly good story, other than the creative premise; better you read Oliver Sacks than search for it.

(And much better you do either than seriously contemplate mutilating your brain!)
posted by Aknaton at 10:07 AM on March 13, 2005


Yes. Probably not. Check Erowid.
posted by bh at 10:13 AM on March 13, 2005


Also used as a plot device in Stanislaw Lem's Peace on Earth: "Ijon Tichy is the only human who knows for sure whether the self-programming robots on the moon are plotting a terrestrial invasion. But a highly focused ray severs his corpus collosum. Now his left brain can’t remember the secret and his uncooperative right brain won’t tell. Tichy struggles for control of the lost memory and of his own two warring sides."
posted by Dean King at 8:32 AM on March 14, 2005


geez ikkyu2, what a buzz kill. We're all like, "Ohh, let's chop our brains up 'n stuff!" and then you're all like "It's dangerous and wrong!"

Haha! No, it's more like "Hey, these funny split brain people are *my* toys. Hands off!" </kidding>

Sorry for the collective buzz kill. Neurology's endlessly fascinating - at least I find it so - and so these sorts of threads are easy for me to respond to.
posted by ikkyu2 at 2:09 PM on March 14, 2005


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