No subject

London, Canada <dsilver at csd.uwo.ca>

I enjoyed reading your summary and commentary of Shadmehr
and Holcomb [1997] Science article. Please stay tuned for
two technical reports myself an Bob Mercer, at Univ. of
Western Ontario are writing on the functional consolidation
and transfer of neural network task knowledge through the
use of a Task Rehearsal Mechanism or TRM. By it's vary
nature, TRM assumes that there are long term and short term
centres for learning as has been the thesis of numerous
researchers (for example see J.L. McClelland, B.L.
McNaughton, and R.C. Reilly, 1994).

The TRM relies on long-term memory for the production of
virtual examples of previously learned task knowledge
(background knowledge).  A functional transfer method is
then used to selectively bias the learning of a new task
which is developed in short-term memory.  The 
representation of this short term memory is then transfered
to long-term memory where it can be used for learning yet
another new task in the future.   Notice, that explicit
examples of a new task need not be stored in long-term
memory, only the respresentation of the task which can be
later used to generate virtual examples. These virtual
examples can be used to rehearse previously learned tasks 
in concert with a new "related' task. The TRM theory has
inspired the development of a system, and a series of
experiments which will be discussed in the reports.

Consolidation of new task knowledge into a
representationally efficient long-term memory is not
explicitedly addressed, however one has to assume that this
process requires time and energy.  If that time and energy
are interrupted ... well, it makes sense that the learner
may suffer in the context of life-long learning. This 
agrees with the findings of  Shadmehr and Holcomb.

See also S.R.Quartz and T.J. Sejnowski, 1996, for an 
article which has very interesting related information on a
potential biological mechanism for CNS learning and
consolidation.

Ref:

J.L. McClelland, B.L. McNaughton, and R.C. Reilly, "Why
there are Complementary Learning Systems in the Hippocampus
and Neocortx: Insights from the Successes and Failures of
Connectionist Models of Learning and Memeory", CMU 
Technical Report PDP.CNS.94.1, March, 1994

S.R.Quartz and T.J. Sejnowski, "The neural basis of
cognitive development: A constructivist manifesto", a BBS
target article accpted for publication by Cambridge
University Press, 1996.

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