Conditioning?

William E. White bwhite at oucsace.cs.ohiou.edu
Tue Nov 2 14:58:59 EST 1993


Forgive me, but I have several questions here; I'm sure my knowledge on this
subject is as out-of-date as the texts here at our library (1989 and older),
and I'm trying to get the background to do graduate work in cognitive AI
and biologically based neural nets.

In article <2a9spl$6qe at news.u.washington.edu> wcalvin at stein1.u.washington.edu (William Calvin) writes:
>      The other type of glutamate channel -- named "NMDA" for
>reasons that are arcane and irrelevant -- allows some calcium ions to
>enter the dendrite as well.  But what's really extraordinary about the
>NMDA channel is that it won't open unless it has two signals at the
>same time:  it takes both the right voltage and the right neurotransmitter
>to open up.  That's like a locked entrance door that requires a valid
>keycard to be stuck in a slot -- but also requires that the power for the
>latch's electronics has to be on.

I was under the impression that glycine was required for the NMDA channel
to operate.  Is this in fact true?


>      Until the discovery of the NMDA channel, all channels had either
>been operated by voltage alone (as in the sodium and potassium channels
>for the impulse) or by neurotransmitter alone.

Just as an aside here, are voltage channels (in mammals at least) ever
involved in conveyance of impulses from one neuron to another, or are
they involved only in propagation of action potential (and dendritic
potential?)

>neurophysiologists -- the calcium entry points to a mechanism for short-
>term memory spanning many minutes.  In the hippocampus (an old part
>of the cortex with a simpler layered structure), long-term potentiation
>sometimes lasts for days, and part of the reason for LTP is the NMDA
>business.

Is there any mechanism yet for memory lasting beyond several days, and
more importantly for converting LTP into this type of memory?

>    William H. Calvin   WCalvin at U.Washington.edu


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