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Author Topic: Why does the left side of our body control the right?  (Read 1424 times)

Offline thedoc

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MANOJ KANNA asked the Naked Scientists:
   
Why are the right sides of our body is controlled by the left part of brain and vice versa?
What is the reason behind this?

What do you think?
« Last Edit: 14/07/2015 07:50:01 by _system »


 

Offline RD

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Re: Why does the left side of our body control the right?
« Reply #1 on: 14/07/2015 09:06:52 »
Early-on in the development of the nervous-system, folding occurs.
Topologically that means crossover must occur ...


http://onlinelibrary.wiley.com/enhanced/doi/10.1002/ar.20731/
« Last Edit: 14/07/2015 09:43:08 by RD »
 

Offline Pecos_Bill

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Re: Why does the left side of our body control the right?
« Reply #2 on: 14/07/2015 15:09:07 »
It is down to the principle of negative feedback in controlling the ability to travel from hither to yon.

Consider the surface to air missile guidance system. Sensors on one side control the contralateral fin. Thus the left and right sensors balance each other's inputs and the airliner is shot down over a cabbage patch in the Ukraine.

Well, just so critters in the Devonian age who first developed a spinal chord used this basic plan to hunt down trilobites. It worked so well. that I am using it to type this today.

Saw that on the "Watch Mr. Science" show when I was 8, didn't I? Childrens' TV was quite different then.
 

Offline RD

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Re: Why does the left side of our body control the right?
« Reply #3 on: 14/07/2015 15:54:56 »
...  critters in the Devonian age who first developed a spinal chord used this basic plan to hunt down trilobites. It worked so well. that I am using it to type this today.

One does not need to be a vertibrate with a decussate nervous system to move towards or away from a stimulus : bacteria are capable of that.

Some say the crossover in the nervous system occurred via rotation "somatic twist model" , when the body plan changed from invertebrate to vertebrate. [ The article I linked to in my previous post argues against such a rotation ].
« Last Edit: 14/07/2015 16:09:26 by RD »
 

Offline Pecos_Bill

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Re: Why does the left side of our body control the right?
« Reply #4 on: 14/07/2015 20:23:20 »
It is true that some echinoderms and molluscs can pursue prey, but that has  not been adaptable to pursuing it on land... so far.

We are safe until the triffids evolve.
 

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Re: Why does the left side of our body control the right?
« Reply #4 on: 14/07/2015 20:23:20 »

 

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