Dynamic connectivity [Re: one more silly "scientiest"?]
Donald Doherty, Ph.D.
donald.doherty at brainstage.com
Mon Dec 30 23:53:54 EST 2002
Retraction isn't necessarily back to the cell body and I believe the axon
typically retracts just a short distance and then reaches back out and forms
a new synapse. I don't think there are data describing the similarity of the
new synapse to the old in terms of location on the dendrite or even if it is
with the same dendrite. In fact, it's this change in connectivity that was a
surprise. (If connections aren't static, how are memories retained? Etc.)
Donald Doherty, Ph.D.
Brainstage Research, Inc.
"Larry" <1o1 at o2.ie> wrote in message news:auq6cv$47h$1 at kermit.esat.net...
> That article refers(as I understood) to a synaptic change... e.g. a
> dendrite will be break a synapse and build another synaptic link with
> another potential axon? which will give sense to his idea in fast
> reconfiguration for artificial neural networks.
> Now, as far as I know side axons are "harder" to find then dendrites. On
> the other side growth speed for both axons/dendrites isn't fast enough in
> order for one/same dendrite to be able to break and form a new synapse in
> matter of minutes? Even this accelerated rate of growth/change might
> in a few exceptional cases I still don't think we can consider it as
> general rule in NN design?
> Or, maybe I reading between lines and this article is not talking about
> "the same connections" but in general? :)
> Donald Doherty, Ph.D. wrote:
> > Rapid extension and retraction of cell processes is well within the
> > boundaries of reality. Brain cells are dynamic living entities with
> > subcellular transport, actin cytoskeletons, etc. Watch single celled
> > organisms such as paramecium and ameba to see how rapid cell processes
> > be.
> > However, some people were surprised to see rapid dynamic processes in
> > adult brain because most assumed that brain connections were static
> > they were formed during childhood.
> > (There are all sorts of reasons for the assumed static adult
> > including ideas about how learning and memory take place, but a complete
> > discussion would take a book or two :^)
> > Donald Doherty, Ph.D.
> > Brainstage Research, Inc.
> > www.brainstage.com
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