basic question

Jan Nauta J.Nauta at uni4nn.iaf.nl
Mon Oct 21 16:01:08 EST 1996


Nigel Foden <n.foden at ic.ac.uk> wrote:

>Jeroen Schaap wrote:
>> 
>> In article <52ov40$4q2 at gap.cco.caltech.edu>,
>>    hdvorak at cns.caltech.edu (Hannah Dvorak) wrote:
>> [snip]

>
>> >{snip some more}
>>         Third, why couldn't any action potential be generated on an
>> axon, by means of axo-axonic synapses etc. Off course the axons don't
>> have the ap generating mechanism, axon hillock, but nevertheless, why
>> couldn't the 'axonic synapses' depolarize enough in order to generate an
>> action potential.
>> What about axon trunks that route together from one area of cortex to the 
>next?  If a volley of (classically) efferent information left a nucleus down 
>several axons that surrounded a non-firing axon, could not the Na+ influx and 
>K+ efflux in the firing cells cause enough local depolarisation to initiate 
>an axon potential in a previously non-firing cell?  Then the stimulus would 
>travel ortho- and antidromically, presumably reaching the soma, although it 
>may not stimulate a second orthodromic ap as the early segment of the soma 
>could still be refractory.  If this mechanism works it provides a synapse 
>free mechanism for synaptic interaction (due to myelination it would 
>presumably be more common in grey tissue, unless the nodes of ranvier line up 
>in nerve bundles, which I don't _think_ happens)

>Nigel

>n.foden at ic.ac.uk
Further, what about the unmyelinated C-fibers, often running together in one
Scwanncell- channel?
Jan Nauta
Groningen, the Netherlands




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