nervous system crossover (hard question!)

[angelo]

why do brains have two halves, and why is information crossed over?

[rosebud]

I think that it may have something to do with the different sections of the brain. Certain things like logic and taste are arranged in different areas. Information is crossed other as things that are on different sides interlink and work together.

Also it means that if individuals become paralysed it may only effect the left/right side of the brain and so it leaves them with some abilities. If we just had one side and that became paralysed then many people would become brain dead.

Hope it helps

[MrMistery]

I think he means is why does the left side of the brain control the right side of the body and viceversa.
Well, first of all, IT DOESN'T! Not entirely, anyway. Some fibres do not cross. For example, the sensitive fibres of the face end up in the lower region of the postcentral girus(i hope this is the right word, my dictionary doesn't have it)ON THE SAME SIDE. The same happens to the motor fibres of the face: they start from the secondary motor region and are for the muscles ON THE SAME SIDE.
But, asides from these small exceptions, let's look into why the fibres do cross:
-One hypothesys is that because one hemisphere controls certain functions and the other controls other function it is better for the fibres to cross so each one will fullfil it's purpose better(Check the dominant hemisphere and non-dominant hemisphere)
-Another(and the most plauzible) is that of being less afected by certain accidents. And this is not because they cross, but because they cross at different levels. For example the cortico-spinal fibres cross both in the rachidian bulb others in the spinal cord.

I believe i had heard a third hypothesis but i simply can't remember it...
Hope i have been of some help...

[GregV]

Why does it cross over?
This is an easy question to answer...

To get to the other side,
of course?

No really, it must have something to do with the way electrical energy works...

Sincerely,

[baikuza]

because if it cross over, we may be get abnormal felling

[MrMistery]

Please explain, baikuza. I don't understand what you mean by abnormal feeling..

[Poison]

I would like to learn this too please.
I havent heard any reason for this. I just know, that is that.

[mith]

my bio book says unknown :\

[baikuza]

ops sorry i think i am miss understand about this. sorry. ( i think it is about neuron not brain structure)

ok. about this topic, right.
if it is not crossed over, i think we will get an abnormal feeling. (yap, this is what i mean. by the way this is only an oppinion/hypotesise)

scientist goes with its felling not only with the infomations. ('hearth' always give the right answer, if we can know how it think)- i think i 'm too much read comics and watch anime.. haha..[ am i can do that? haha..]

ok, then
it is pretty analog to this.
when some thing goes to keep / control something at other side. it it much better than if it is control at its side=> at this case to keep a good syncronization with the other side (left to right/ right to left)
u can imagine by this
if some thing that should be at good sycronization goes do its own business only not get to look at the another.(quite not good, right?)
when this occurs to our brain(u know what i mean) our body would not goes at a good syncronization.
even though it is happen to any organism since they born.

.. sorry but i do not have a sample to prove this.
i hope you are satisfy

[victor]

hmm...quite unreasonable...if you don't have proff, at least, do you have any related proven theories with this kind of crossover??

[MrMistery]

Oh and by the way, for the first question: the brain has too halves probably to separate the neurons of one side of the body from those oof the other side and also to provide more space for the cortex

[r10]

I think it works similarly to the eyes, when an image is received it becomes inverted at the lens and then the information is sent to the brain upside down and the cortex interprets it right-side up. Similarly when the PNS relays information to the brain through the thalamus into the proper motor and sensory regions. The proprioception (the brains understanding of where individual body parts are in order to control them) makes the nervous system cross-wired. If the brain was not cross-wired it's possible when trying to control the right arm the person may move the left and does match the perplexity of the brain and proprioception.

Please let me know what you think