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memory (and SOMs)

yan king yin (dont spam) y.k.y at lycos.com
Sun Feb 3 02:01:37 EST 2002

Im just reading an intro to SOMs and am wondering how could you construct
a memory system out of one or several SOMs. I think any iterative mechanism
is unlikely to occur in the brain, unless you can point out a specific circuit for it.
Also the memory system has to be unsupervised. The SOM algorithm seems
to require supervised training which makes it not so biologically plausible.

------------------------- Original Message -----------------------------
mat wrote:

The memory functions of the brain are certainly impressive but not of
course not infallible.  An interesting point is that we often seem to
know when we have recollected a name or a fact (for example)
incorrectly.  By implication this must mean we either have the correct
memory somewhere with which to compare it (in which case why don't we
just recall that?) or that there is another error-checking system of
some sort.  Just wondering if anyone had any ideas.

One possible mechanism through which you get some of these properties
would be to use two or more neural network-type systems (particularly
the self-organizing map (SOM) paradigm).  When a memory was to be
accessed then the 'request' would be sent through the first SOM.  Some
output from this frist SOM would then be input to a second SOM.  If
the output from the second and first matched then the memory would be
considered 'correct'.  However, if not then the output of the second
SOM would again be input to the first SOM.  Eventually you would end
up such that the output and input to each SOM was the same and this
would then be considered correct (of course it still might actually be
incorrect).  If the outputs and inputs never converged then you would
have 'forgotten'.  The process is similar to the iterative formulas
for finding equation roots where you use the output as subsequent
input until there is no change (to a defined degree of accuracy)

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