ARMY GUYRe: Memory (and SOMs)

JASON AND STACIE DOUGROCK27 at MCHSI.COM
Fri Mar 8 22:35:06 EST 2002


I am looking for anyone with the Arnold-Chairi Malformation, please email if
you are familiar or have it yourself,  thanks, Jason
"Matt Jones" <jonesmat at physiology.wisc.edu> wrote in message
news:b86268d4.0202180937.45bf8f90 at posting.google.com...
> "yan king yin" <y.k.y@(dont spam)lycos.com> wrote in message
news:<ZB2b8.467$B92.91629 at news.xtra.co.nz>...
>
>
> > > I agree with this too. For example, one area in the brain thought to
> > > be critical for consolidation of short-term memory is the hippocampal
> > > formation and associated entorhinal cortex. The iterative structure
> > > looks like this:
> >
> > You should be careful that consolidation is different from recall, and
> > the hippocampus is required for consolidation, but not recall. There
> > is also the additional complication that hippocampal lesions usually
> > result in a few years of retrograde amnesia as well.
>
> Perhaps consolidation is different, and perhaps not. How does an
> experimenter know whether a memory has been consolidated unless the
> test subject is also able to recall it? Either way, the hoippocampus
> appears to be important in recall of memories that have just been
> acquired (short-term). The famous example of being able to remember 7
> plus or minus 2 digits of a phone number is sensitive to hippocampal
> damage.
>
>
> > I suppose you're talking about memory recall here, but hippocampus
> > is not involved in recall of long term memories. Though you may argue
> > that this is the recall mechanism of recent memories that is stored in
the
> > hippocampus.
>
> Right. I think everyone agrees that long-term storage is somehow
> distributed around cortex, not in hippocampus. Also, there are several
> kinds of memories that appear to be little if at all affected by
> hippocampal damage.
>
>
>
>
> >
> > Another simplified schematic pathway is as follows: cortex -> EC ->
> > dentate gyrus -> CA1 -> CA3 -> Subiculum -> EC -> cortex, where
> > CA=hippocampus. So it looks like a loop and memory might pass through
> > this loop to be stored in the cortex. It is also possible that memory is
> > processed in other parts of the cortex and the hippocampus only
> > mediates the consolidation process.
>
> I think you mean dentate->CA3->CA1...
>
>
> >
> > I think the central question is in where and how is memory stored
> > in the cortex.
>
> I do not necessarily think that is the central question. The long-term
> storage might be the very last step in the process. Lots of other
> steps are probably very important. For example, decisions about which
> experiences are worth storing and which are not are probably pretty
> important steps. We don't store everything, only some things. Some
> theories suggest that the selection of events for storage takes place
> in hippocampus, and involves a comparison of new information with
> previously buffered information. If the new information is
> sufficiently different, then it gets processed and eventually stored.
> If it's very similar to previous information, it may get ignored
> because there's already a copy of it. There is a dual role of memory
> processing at work, where similar information gets compressed into a
> single representation, whereas novel information gets differentiated
> from previous information. The hippocampus appears to be involved in
> both of these processes, without which the cortex would just fill up
> with a lot of extraneous information that isn't much use to the
> animal, and was stored in a very inefficient manner.
>
>
>
>
>
> >lished, but I saw his Neuroscience poster.
> >
> > This sounds similar to the idea that the hippocampus forms a "cognitive
> > map" of the environment.
> >
>
>
> Yeah, I think the SOM work, and many other modeling efforts, are
> attempts to develop a computational mechanism by which such cognitive
> maps may be implemented.
>
>
> cheers,
>
> Matt





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