Weighting of synaptic responses
Ferber at zoology.uni-frankfurt.de
Sat Aug 24 00:16:52 EST 1996
In article <4vofut$s8f at reader1.reader.news.ozemail.net>,
rreich at shell02.ozemail.com.au (Rose Reich) wrote:
>Q: In a modeled neural network the input into a neuron is regulated via
> a weighting mechanism. In "real" brains is this performed by regulating
> Na+ concentration within the dendrite thus changing ion gradient, having
> a nett effect on the input level at the hillock ? or is it done some other
> way ?
Fro where does the information about the Na+ come? From my understanding, the
wheighting or strength of a synaptic connection between two neurones (a single
neuron can be connected to several hundred or more other neurones) is
represented in the size of the postsynaptic potential. Changing ion
concentrations (better activities) in the dendrite of the piostsynaptic neuron
would affect all inputs in a similar way.
Nevertheless the strength of a synaptic connection (the amplitude of the PSP)
may change as a result of a change in the amount of transmitter released by
the presynaptic cell, by changing the number of anatomical synapses between
two neurones which will lead to greater postsynaptic ion-currents, by changig
the sensitivity of the postsynaptic cell to the transmitter (for exmaple by a
modification of receptor coupled ion-channels), or by other mechnisms
(Suggestions are greatly appreciated).
>Q: How is this weighting controlled? In a modeled neural net one simply
> adjusts the weighting vector, but how is this achieved in real brains ?
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