left-right reversal of CNS: Why?

Henry M. Wieman wiemanh at ma.ultranet.com
Tue Sep 3 19:56:18 EST 1996


In article <322CC0E8.7CFC at postoffice.worldnet.att.net>,
   kenneth paul collins <KPCollins at postoffice.worldnet.att.net> wrote:
>
>The nerve-fiber termination distributions that result align with the 
>totally-inhibitory outputs of the cerebellum so that the problem of 
>activating the muscles to move away from environmental sources of 
>noxious stimulation can be resolved by "simply" minimizing the 
>topologically-distributed ratios of excitation to inhibition (TD E/I) 
>occurring within the neural architecture...
I'm afraid I'm not following this. The cerebellum is not reversed, so 
inhibitory neurons from there could project to cortical areas affecting the 
other side of the body, but how does that help you move away from noxious 
stimuli? Withdrawal involves both muscle stimulation and inhibition; your arm 
doesn't go limp when you touch a hot stove. Moreover, there are inhibitory and 
stimulating neurons in the cortex are there not?
>The anatomical antecedants of the the bilateral crossing phenomenon 
>("decussation") can be traced all the way back to organisms exhibiting 
>radial symmetry... coelenterata... jellyfish...
How can a radially symmetric thing be bilaterally crossed?
>ken collins
Are there any references to this idea so I learn more about it??

   	Henry M. Wieman          | "Can you answer? Yes I can!
        wiemanh at ma.ultranet.com  |  But what would be the answer,
        Call me Hank             |  To the Answer Man?"
                                 |       -Robert Hunter in St. Stephen



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