Trouble Thinking

April 12, 2010

Half a Head is as Good as One.

Filed under: Science — Tags: , , , — Durandal @ 5:25 pm

So when I was in high school, we got a speech in health class about how drinking was bad so bad that every time you did it some of your brain cells died and brain cells never regrew. Also, same with pot. Now, although I was pretty certain that wasn’t completely accurate, it stuck with me that every single time I bumped my head or had a drink brain cells died and never came back. The older I got, the stupider I’d get, until finally I’d demand that my local paper continue running Hi and Lois.

Finding out about hemispherectomy patients has made me a lot less concerned about losing a cell or two.

When someone is severely epileptic, the condition can be so debilitating that drastic measures are taken to allow them to enjoy a quality of life that went beyond “excellent at flopping about”. If someone is lucky enough to have severe epilepsy- which is to say very unlucky – but also lucky enough to have a distinct “focus”, a point in the brain from which the seizures tend to spark -which is to say moderately lucky again- that focus can be removed through a lesioning procedure. Now, lesioning procedures are as varied as they are awesome, but the point is they’re left with a tiny chunk of brain matter removed and no more epilepsy. As that brain matter wasn’t actually used for anything but fucking with them, they actually tend to do better on various IQ tests and whatnot than they did previously, what with no longer needing to worry about having sudden fits and having the area around the focus re-dedicated to “thinking” instead of “frenzied chaos”.

What’s the treatment if that focus takes up one entire goddamn hemisphere of your brain, you poor bastard? You’d think “not cutting out one entire hemisphere of your brain, you fucking madman” but you’d be entirely wrong. The treatment is totally cutting one of your hemispheres out and just tossing it in the tray like it wasn’t controlling speech and half your motor functions.

On the plus side, you have a bit more storage space.

You cut out the VESTIGIAL half, right?

So you can imagine the patients that undergo this barbaric and debilitating medical procedure. I mean, not only have they lost fully half of their brain cells, they’ve lost specialized structures dedicated to speech, vision, hearing, and control of the opposite side motor functions. Stroke victims have it lucky compared to these poor saps. You’d imagine, that is.

As it turns out, they’re fine. Let that sink in for a few moments. There is more than one person alive today with literally half a brain. And you can’t tell the difference. In fact, there are good odds someone with half a brain is smarter than you. More than one patient has gone on to graduate school and a successful career in being smarter than you.

How much of an asshole are you for not using your double-sized portion of brain to get two PhDs, two jobs, two women?


Too many lady-friends to count.

Now, obviously there are caveats. So put down that meat cleaver and bendy straw, you’re not liscensed for that kind of work anyway. The outcomes in these cases are by no means always rosy. Many of the people treated in this manner already had significant and permanent impairment for a variety of reasons. For the most part, people who get these surgeries are so bad off that permanent loss of motor function on one side is considered a worthy trade off. That said, when performed on young children, below the age of 6 or so, the recovery is amazingly swift. Even in children who have other mental or physical disorders it only takes a few years before they function significantly better than before surgery.

In adults, it’s more of a risky deal. Your brain, by the time you’re around 20-25, is basically where it’s going to be forever. Well, not forever, but until it decays inside your head like a rotting grape, grandma. There are structures in there that have been pretty well proven to “control” various functions, as far as we can tell. For instance, your left brain has a portion that seems dedicated to speech and writing. Without, your only vocal output is a hilarious sounding mish-mash of random sounds. Most of the time when someone gets any bit of their brain chopped out, it results in one of a variety of flavors of impairment that lasts forever, or in rare cases cherry. Adult brains just don’t seem to be able to re-wire as thoroughly as young ones can.

However, one case study of an older male who had his left hemisphere removed reported, insanely, that he got markedly better from January to June. He went from not being able to speak, to being able to speak reasonably well. He was able to care for himself. His “libidinal drive was intact” according to his wife hello. Apparently his personality hadn’t even changed. He just had, you know, a storage space in his skull now. He even gained some control of his right side motor functions. So even after years of having his brain pretty well used to using only the left side to do a bunch of very important tasks, it took only a few months to re-wire it to the point that his right side took up the job.

So how in the hell is this possible?

Well, one theory is simply that the right and left sides of your brain each do everything. That is, they may look specialized, but that’s simply because each side mostly does a specific set of tasks. Most of the time, the left hemisphere takes care of talking. But the right hemisphere still has a “can talk” chunk in it, it’s just small because it’s the backup. Plausible, but also really weird. Why split any function 80/20 when you could split 50/50 and maintain more function in the event of some crazy dude scooping out half your brain? Perhaps there are advantages to having the function localized to a certain point in terms of speed or ease of access.

I think it’s interesting that apparently, the arrangement of parts matters a lot more to total processing power than how much raw material there is inside of the head. Now, this is pretty obvious simply from seeing how blue whales do not in fact rule us from the deep-city.

But mark my words, the day WILL come.

Our brains are markedly smaller than many animals, and yet way better at thinking. The weird part about a hemispherectomies is that they’re examples of even smaller brains that work just as well. So it isn’t that you need X neurons gathered in Y place connected thusly to make a brain like ours, it’s that you need a certain basic arranging principle, and it will work with whatever it’s got. So what’s all that extra mass do? Backup systems?

It would be interesting to see exactly how much brain can get cut out of an infant and leave them without any noticeable impairment as an adult. Um. Not that I would do that or anything. You can totally trust me to babysit. At least until I get funding.

1 Comment »

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    Comment by insomnia After an operation — September 25, 2014 @ 10:44 am

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