[MURG] Non-invasive 3-D Scanning

[digfarenough]

just thought I'd inject some info, as I saw a talk by
john lisman today that relates to this..

> >2) synaptic strength -- the size of a synapse is
> quite
> >    stable, at least longer than LTP. BTW, some
> weaker
> >    components of LTP may last longer than hours,
> to
> >    days (or weeks?) IIRC.
> 

in vivo ltp can last a long time, it makes structural
changes to the synapses.. lisman showed the results of
a simulation that showed it doesn't take very many
(~10) activated CamKII molecules to be able to hold
information for very long periods of time (order of
10s or 100s of years)

> Right.  At 10 nm resolution, you can measure the
> size of a synapse, 
> and with that and the morphology of the postsynaptic
> process 
> (dendritic spine or whatever it may be), you can
> probably estimate 
> the strength.
> 

I forget the exact scale (but I think it's about the
size you mentioned), but CamKII is big enough that you
can pick out the molecules of it at synapses under EM,
and since it associates with NMDA and AMPA channels
you could basically count the number of them and get a
good idea of the synaptic strength

I'd also like to point out that it isn't firmly
established that LTP is actually the basis of
memory/learning :)

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