[MURG] Non-invasive 3-D Scanning

[Randal A. Koene]

Hi there,

Just to interject my take on this. What John was presenting at BU that day
is actually stuff that Eric Kandel described earlier (and in some high
profile Science papers). But, this so-called "late-LTP" is often believed
to be the precursor to long-lasting morphological plasticity in synapses.
Its dependence on protein synthesis is very similar to that of
morphological changes and quite distinct from the processes seen in early
LTP.

If you're willing to overlook such an intermediary stage, possibly the
conversion to lasting memory, then you can still make do with
morphological data.

BTW, I think John is stopping by my office tomorrow morning to see if I
can quickly whip up some Catacomb models (he may be interested in using
it!), so you can drop by and ask him about it if you like. I think he's
working in the guest scholar's room in 109 all this week.

Cheers,
       Randal

On Mon, 15 Dec 2003, digfarenough wrote:

> 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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