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Author Topic: Half a brain here, half a brain there...why ?  (Read 4653 times)

Offline neilep

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Half a brain here, half a brain there...why ?
« on: 04/05/2004 23:17:39 »
Hello,

As I understand it my brain is like this planet !..err..It has two hemispheres yes ? ........Why ?

......I know there are organs which are duplicated like Kidneys, lungs etc...oh...and all the ones on and in my head too. Is this duality by design so that if one part stops functioning then the other can take over ?...but of course, the brain (or is it brains ?) is not as straight forward as that is it ?...each part of the brain has a specific purpose though I have heard that in the case of injury (a stroke etc) there are times when parts of the brain act as a backup yep ?...My brain and I would appreciate some incite as to why my brain/s are/is in two halves....and why not two hearts then ?

'Men are the same as women...just inside out !'
« Last Edit: 04/05/2004 23:25:09 by neilep »


 

Offline Donnah

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Re: Half a brain here, half a brain there...why ?
« Reply #1 on: 05/05/2004 00:29:31 »
Well Neil, in your case, with the massive amount of grey matter in your noggin I suspect that it's 'cause if you only had a brain (no, not the Wizard of Oz song)....on one side, your head would lop over from the imbalanced weight.
 

Offline bezoar

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Re: Half a brain here, half a brain there...why ?
« Reply #2 on: 05/05/2004 00:36:32 »
There are some functions that are localized to one side only.  And generally, younger brains recover better from injury than older ones.  I suppose that's because the functions aren't so clearly delineated to one side or the other.  There are some kids with severe epilepsy that actually have half of their brain removed.  They seem to do fine, but of course, they do have a slight limp and slight loss of function of one arm.  Not real severe though.  It's amazing how much brain you can do without.
« Last Edit: 05/05/2004 00:51:06 by bezoar »
 

Offline neilep

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Re: Half a brain here, half a brain there...why ?
« Reply #3 on: 05/05/2004 01:19:37 »
lol..thanks Donnah....good job us Brits are good at keeping a stiff upper lip then eh ? helps with the balance !!


Nancy, that's amazing how the epileptic children only seem to have minor consequences after half their brain is removed. What about their speech and other cognitive abilities ?.....are they, for the most, also not affected to a great degree ?

'Men are the same as women...just inside out !'
 

Offline Ylide

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Re: Half a brain here, half a brain there...why ?
« Reply #4 on: 05/05/2004 08:24:47 »
Sort of related topic:

I've heard that deja vu is really a situation where one side of your brain interprets and processes your surrounding slightly faster than the other side, causing a sense of familiarity while the other side finally catches up and perceives everything for the second time.  I'd like to hear a medical opinion on this.  



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Offline neilep

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Re: Half a brain here, half a brain there...why ?
« Reply #5 on: 05/05/2004 10:39:17 »
Now that is very interesting Jay....I've always wondered about Deja Vu....I await the medical opinions too...(hang on...I think I've said that before !!)

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Offline Donnah

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Re: Half a brain here, half a brain there...why ?
« Reply #6 on: 05/05/2004 19:26:15 »
I haven't had deja vu for a while, but I usually get it just before something odd happens.  For example, when Bruce and I were driving we took an exit and I said "I thought we already turned on this exit", and suddenly there was an obstacle in the road.  

How can you study deja vu?  Wouldn't it just be analysing a compilation of experiences?
 

Offline neilep

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Re: Half a brain here, half a brain there...why ?
« Reply #7 on: 05/05/2004 23:49:39 »
...what kind of obstacle was it Donnah ?...a delinquent trout perhaps ?...or a herd of wildebeests ?:D

I agree though...can't see how one could actually do empirical study on Deja vu..unless someone was found to be experiencing it every day.........

I presume it's such a rare occurrence that it would be nigh on impossible to research.

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Offline tweener

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Re: Half a brain here, half a brain there...why ?
« Reply #8 on: 06/05/2004 03:51:00 »
I have deja vu often (not "quite often") where I "see" something, kind of like a dream, and then later it happens, exactly as I saw it. Usually much later, sometimes several years.  The "dream" is incredibly detailed, just like being there.  Usually, it is something trivial, like chasing the dog in the back yard and tripping over him, or walking up the driveway.  Sometimes it is something more substantial like flying a helicopter (which I don't).  It is always very short, like 3 to 5 seconds.

I've found that if I recognize the situation, I do have the "free will" (don't know if that is the right term) to change the outcome to something other than the "dream".  Or I can play along and let things unfold, knowing exactly what will happen.  

I have a couple of really scary ones that haven't happened yet, and I'm hoping they don't, or that I can change them if they start to.  But they don't seem to be changeable if I'm interpreting the situation correctly.

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Offline chris

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Re: Half a brain here, half a brain there...why ?
« Reply #9 on: 06/05/2004 09:04:30 »
The original thrust of this thread was why does the brain have 2 similar, yet different halves ? The simple answer is we don't know.

The issue is referred to as hemispheric specialisation, and despite the fact that we have known about this for over 150 years we are still no closer to knowing a) why we have it at all, and b) why the nervous system is 'cross-wired' such that the right side of your brain controls the left side of your body and vice versa.

One of the confusing things about the brain is that it looks very homogenenous for the most part. A wrinkled up surface which, when cut open, reveals a thin grey 'rind' (the cortex) covering a fatty white interior within which nestle a few other grey areas, no pun intended.

However, in 1861 Frenchman Paul Broca published the case of 'Tan' as he was known because that was the only word he could say. Tan had been normal until he suffered a stroke that left him able to utter just that one single word. His ability to comprehend what was said to him, however, was left unaffected.

When Tan died, a post mortem revealed a very discrete region of the brain, on the left side at the front, had been destroyed by the stroke. Broca correctly deduced that this part of the brain must be the seat of expressive language, and indeed we still refer, in his honour, to 'Broca's area' today.

We now know that the brain is highly specialised all over with different regions devoted to performing different tasks and functions. There are also sex differences in terms of how well the brain performs some of those functions. Men are generally accepted to be superior at mental arithmetal tasks and visuo-spatial tasks (be honest girls, how often do you need to turn the map upside down whilst driving ?), whilst women usually outperform men on tests of verbal skills.

Nancy mentioned above, quite correctly, that there are children who have undergone surgery resulting in the loss of half their brain, yet they appear relatively normal inspite of such radical intervention. This would not be the case in an adult and highlights another cery important aspect of how the brain develops and functions.

When we are born the brain is in an immature state that can readily be moulded by experience. Indeed experience of the world is absolutely crucial to making the brain function normally. People born with eye problems that are not correctly sufficiently swiftly may never see, even if the eye problem is subsequently treated. This is because the brain needs to learn to see. Experiments on kittens has shown that if they are prevented from opening their eyes until they are 6 weeks old then they remain blind for life. If you analyse the brains of these animals you see that the brain looks completely different (at a microscopic level) to a normal 'seeing' cat.

There is therefore a critical 'window' of opportunity during which the brain can be remoulded and can accommodate even quite radical changes to its function and structure. Whole regions of the brain can switch allegiance to performing other tasks. In one case I saw a guy was born without a temporal lobe on one side of his brain. But he wasn;t deficient in all of the functions that are performed by that (large) part of the brain (memory, face recognition, smell, some higher visual processing). Instead these processes had been relocated to another part of the brain, as revealed when he was brain scanned.

It's an intriguing organ, and we've not yet begun to scratch the surface.

For more information on the brain's asymmetry and hemispheric specialisation check out the interview with Prof. Chris McManus from UCL (winner of the Aventis Book Prize 2003) - here are the links :

http://www.thenakedscientists.com/html/shows/2002.07.21.htm

http://www.thenakedscientists.com/html/shows/2003.11.16.htm

Chris

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Re: Half a brain here, half a brain there...why ?
« Reply #9 on: 06/05/2004 09:04:30 »

 

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