Thread: A man is cut vertically in half...

I would think his neural network would go absolutely haywire. Being split right down the middle is going to sever an untold number of nerves, so I doubt he'd "feel" many portions of his body - at the very least, with any sort of acuity.

For his last few moments, I would think that he'd actually feel like he was just there - "in both sides," as it were. I don't know that he'd feel a great distinction between left and right sides, or he'd feel one with the absence of the other.

It is an interesting question, though.

It is an interesting question, but I doubt the brain would function enough for him to have any sense of self at that point.

Why don't we find out?

Hook up them neuro-thingy's to a POW's head, and chop 'em in half with a guillotinbe, and record the results.

Here is my answer... I am pretty confident in it.

First of all, let me set off with the condition, to humor your thought experiment, that the two halves of the brain were in fact functional halves after being broken in half. Let's pretend they could in fact "think" thoughts, etc.

Anyways, my answer is, both. If you think about it, it is really not that hard to understand how. If you believe in the "mind," perhaps it is a bit harder to comprehend. But personally, the mind is just what the brain does, in my opinion. So pretending that the two halves of the brain work, the man would have one thought process going on in one side, and another in the other side. As if it were another person (but in this case the same brain and DNA). Do you understand where I am coming from here?

Originally Posted by Oneironaut

I would think his neural network would go absolutely haywire. Being split right down the middle is going to sever an untold number of nerves, so I doubt he'd "feel" many portions of his body - at the very least, with any sort of acuity.

Actually, deliberately severing the two hemispheres of the brain is one type of treatment for epillepsy. See: http://en.wikipedia.org/wiki/Split-brain

I think the answer depends on what processes what. Like, if feeling the left side of your body is controlled by the right side of your brain, then you won't feel a thing, since it's disconnected. I'd think everything that doesn't involve a dependency between the two halves of the body will function normally for a few seconds, including probably the optic nerve, hearing, and (maybe) touch, depending on stuff.

Originally Posted by Replicon

Actually, deliberately severing the two hemispheres of the brain is one type of treatment for epillepsy. See: http://en.wikipedia.org/wiki/Split-brain

And there also exists a procedure where a whole hemisphere is removed/disabled http://en.wikipedia.org/wiki/Hemispherectomy.

So it's quite possible to survive with only one hemisphere, thus the two halves would probably have individual consciousnesses.

Of course, they would lack the functions that are unique to the missing hemisphere and they would have no control over the remainder of their bodies or senses (since the brain hemispheres control opposite sides of the body).

he would be for a very short time be in two places at once. if you could read his mind you would most likely get a poem and some observation. (or just babaling)

That would not only sever the corpus collosum, but also would split several parts of the limbic system and the thalamus, not to mention splitting the brainstem in half. Because the thalamus and brainstem connect the afferent neurons in one side of the body with the opposite side of the brain, all sensory input(with the possible exception of smell) would be cut off. In most people, the left brain is the area where lingual, analytic thought occurs, but other processes occur in the right brain. In experiments with split brain patients, the different sides of the brain seem to exist independently of each other, although in those cases the brains are still connected in the brainstem.

The personality is split in half. Now to conscious beings exist.

Good question!

Ha good question. I do not believe a person would be concious enough to tell the difference, but for the sake of argument... Unfortunately, the left side of the brain controls the right side of the body and vice versa. It could be a split conciousness, but there would be no feeling.

Originally Posted by Replicon

Actually, deliberately severing the two hemispheres of the brain is one type of treatment for epillepsy. See: http://en.wikipedia.org/wiki/Split-brain

This, though, is a result of a surgical procedure. I would think that the end result would be a lot different from someone taking a guillotine through the body. I'm not saying that just by having the brain cut in half (no matter the procedure) it would cease to function, only that having a blade slice straight through your body is a much more crude process. I don't know enough about the brain to know what processes what sensation, but as far as perspective, I think the man would still feel like a single person, all though the impulses going through his (now severed) mind would be without logical order. Haywire.

This reminds me of amputees reporting on having an itch in their missing limbs! Now that must be a pain!!!

Anyhoo - I don't have an answer, just thought I would share the above.

Originally Posted by Oneironaut

This, though, is a result of a surgical procedure. I would think that the end result would be a lot different from someone taking a guillotine through the body. I'm not saying that just by having the brain cut in half (no matter the procedure) it would cease to function, only that having a blade slice straight through your body is a much more crude process. I don't know enough about the brain to know what processes what sensation, but as far as perspective, I think the man would still feel like a single person, all though the impulses going through his (now severed) mind would be without logical order. Haywire.

I think the point is what would happen if you seperated your brain in two halves (ill effects set aside for the sake of argument). Would you obtain two seperate consciousnesses for example?

On a more simplistic level, what happens when a bacterium splits? If only bacteria could talk...

If two consciousnesses are created, where is the continuity for the man's consciousness? Does he go into one of them, and then a separate new one is created? Or do two new perceptions arise and the man's original consciousness is destroyed.

Most likely, both halves would have a sense of being the whole self independently from each other.

But which half does the man feel like he is??

Originally Posted by sephiroth clock

But which half does the man feel like he is??

They become two separate entities. Both halves feel like they are in their respective halves.

Originally Posted by sephiroth clock

If two consciousnesses are created, where is the continuity for the man's consciousness? Does he go into one of them, and then a separate new one is created? Or do two new perceptions arise and the man's original consciousness is destroyed.

What happens with split-brained people is that the consciousness does get split in half. Left brain functions are only available to the left consciousness, and right brain functions are only available to the right consciousness. Each half is only conscious of the opposite half of the body and the visual field. This does cause certain problems, but split-brained patients are usually relatively normal individuals. It might be possible that, subjectively, the person is still conscious of both sides of the body, but they are unable to exhibit behaviors that suggest this.

We have found that we can survive with half of the brain. Literally.
Amazing as this seems surgeries are performed for various reasons and worst cases require the removal of an entire hemisphere.

I once watched a documentary where they actually talked about a guy who had an entire hemisphere removed and besides limited control over half of his body, he was perfectly fine. That made me wonder what would happen if they did such surgery to a healthy brain and installed the removed half into an extra empty headed body.

You'll notice that when a zygote splits in half, it produces two independent consciousnesses which both think themselves to be 'the original', if you will, and both experience consciousness in their respective body.

These are called 'identical twins'.

Of course, assuming the zygote is not conscious, the development of one unconscious thing into two conscious things is a bit different than the separation of one conscious thing into two conscious things.

However, seeing as one or the other half of the brain can theoretically be removed without entirely destroying the consciousness, the most likely outcome would be two conscious entities which both thought themselves to be the 'original' and experienced consciousness from their half of the body. The general idea of one consciousness splitting into two is evident in split-personality disorder.

I'm with Belisarius that the proposed method would sever the brainstem, causing instant death, but if we did isolate and sustain both hemispheres somehow, it would probably create a fork in the mindstream. Both hemispheres would identify with the undivided consciousness up to the split, and after the split, they would proceed as two different entities, each carrying on only some of the qualities of the original.