Right brain , left brain

Why does the right side of ur brain control the left side of ur body and vice versa and how do ppl become ambidexterous

first of all statistics show that more left handed ppl are ambidextrous than right handed ones
so jay, forget it
a very interesting fact is that if u are armless and ur ambidextrous, it could be ur feet which u can use with equal ease – amazing
Michelangelo painted with both his hands
einstein, fleming were both ambidextrous

as for the brain, im sorry but i dont remember the name of the parts but the left half of the brain is connected to the right half of the body and vice versa

Has anyone heard about the experiments done on people with seperated hemispheres? I remeber reading about the artificial generation of synesthesia by this means but there were also many other implications of this brand of split brain research. I understand the Nazis had quite an intensive program of research into this area too.

I’m actually right-handed and right-brained, but I’m not sure how or why that happened. AFAICT, this has affected my life in no way whatsoever.

I understand this is very rare (something like 1% of people are wired this way), but still it shows that people aren’t necessarily opposite hemisphere dominant.

I have also wondered why the left brain controls the right hand side. After all, if an angry mammoth gored your rhs good and proper, you may lose the use of your right arm through muscle damage and your left arm through brain damage.

Yup. It’s been a while since I studied this stuff, but a cut along the corpus callosum affects how the brain absorbs and processes information, and thus hinders learning. That’s really vague, and I apologize. I’ll go dig out my books and notes and pray that someone who can fight ignorance more eloqently shows up…

[Neuroscientist checks in]

They’re not sure why, evolutionarily speaking, muscular control crosses sides at the base of the brain. I think the general feeling is that if you’re hurt on one side of your head, you can still defend yourself on that side (your attacker is currently on that side, obviously). Presumably enough early chordates (with the mutation to cross control to the other side of the body) survived such encounters (whereas those without said mutation would not have) that the mutation stuck.

But we can’t exactly reconstruct the evolution. :slight_smile:

As to separated hemispheres, there are many implications to it. (The experiments tend to be performed on persons who have had the corpus callosum–the part of the brain that connects the two hemispheres–cut to reduce severe epilepsy.) One of the most startling early finds was that vocal control is entirely on the left side of the brain. A person with a cut corpus callosum cannot name, verbally, an object that is shown to him in the left side of his visual field. He may be able to write the name–with his left hand–and he’ll know what he’s looking at–but the left side of his brain wil have no idea what he’s looking at, and the speech area simply won’t get any signals.

Move the object to the middle or right visual field, and there’s no problem.

tater: What do you mean by being “right-brained,” exactly? There are many different ways to define brain hemisphere dominance.

What I want to know, though, is what part of the brain causes people to need to abbreviate a three-letter word, “you,” to one letter, and a six-character word, “you’re,” to two letters.



Heh, I’m off the hook! :slight_smile:

To nitpick :

At least as I was taught in medical school, this only applies to right handed people. Broca’s and Wernicke’s areas (the motor and vocabulary speech centers) usually associate with the dominant hemisphere of the brain – in most right handed people this is the left brain. In lefties, however, this is often the right side of the brain, but also commonly, the areas are more distributed between the hemispheres.

The same is true of the temporal lobes – the nondominant versus the dominant temporal lobes control different aspects of orientation and direction sense. Again, this is usually controlled by the dominant hemisphere, but in lefties the functions may be distributed more evenly. The same applies to other centers like the hippocampi.

Interestingly, this may suggest that this subset of lefties have somewhat of a selective advantage when it comes to stroke or traumatic brain injury, which is usually localized. Having the centers distributed may give an increased fitness in these situations.

Split brain patients also have other bizarre findings besides the naming aphasia described above. I’ll dig up my neuro syllabus when I get home – they deal with pictures of objects differently, they deal with hand manipulation differently, etc.

Not in the sense of being creative or emotional in my thinking, more like what edwino said:

To be honest, I’m not sure how my psychologist determined this. I was in a psychiatric hospital at the time and the psychologist doing the testing noticed something about the way I held my pencil (I hook my hand around and rest the pen on my ring finger, so it almost looks like I’m holding the pen in my fist) and he did a few more tests (long time ago, don’t remember them too well) and determined that I was right-dominant. To be honest, I think it was more of a curiousity thing and I have no idea if he was a quack or what. He seemed pretty on the level, though. :slight_smile:

And I’m not in the least bit ambidextrous, in case anyone was wondering.

Ah, yes, very good point… and one that I’d completely forgotten. Good catch.


As a male leftie, I can definitely assure you that I am much less lateralized than a lot of the right handed people I meet.

Women are also statistically less lateralized than men. Women tend to recover more quickly than men from aphasia due to injuries to the temporal lobes. I’m very curious about lateralization of brain function in left handed women. I suspect that they will be more lateralized than normal.

Living in a right handed world intrinsically forces lefties to become more ambidexterous.

If you would like some really interesting examples of what results from a full or partial commisurotomy (separating of the hemispheres) read about some of the case studies in;

“The Origins of Consciousness in the Breakdown of the Bicameral Mind”

The book by Julian Jaynes is extremely interesting and contains many details about brain function.