which came first the idea or the model?

[James M. Bower]

Not to pick nits, but,

In response to Richard Granger:

In his original email he stated:

>This (iterative finer grained representation of an odor) is an instance in
>which modeling of physiological activity in anatomical circuitry gave rise to
>an operation that was unexpected from behavioral studies,

However, the idea that cortical (olfactory) processing involved iterative
response refinement and specificity was actually a central thesis of the
monograph published by Lynch in 1986.  This monograph includes a discussion
of supporting behavioral data.

Reference:  G. Lynch, Synapses, Circuits, and the beginnings of memory. MIT
Press. 1986

It was clearly the objective of the subsequent model by Granger and Lynch
to see if this specific idea could be incorporated into a "cortical like"
structure.  Thus, as I indicated earlier, the model essentially served to
demonstrate a particular idea, which as Richard points out is still
controversial.

Second, the first reference I know for the Granger model was actually in
1988, two years before publication of the physiological studies claimed to
serve as its foundation:

Reference:  Granger et al., Partitioning of sensory data by a cortical
network, Neural Information Processing Systems. D. Anderson Ed. AIP, 1988}.

To quote previous email:


>"physiological induction and expression rules for
>synaptic long-term potentiation (LTP; Kanter & Haberly, '90; Jung et al.,
>'90)."

In fact, as I remember, the Granger model assumed that the only LTP was in
the synaptic connections made by the Lateral olfactory tract (LOT) not in
the association fiber system.  Kanter and Haberly (1990) actually showed
that the association fiber system is the major source of LTP in olfactory
cortex.

Thus, in summary, models can indeed generate novel ideas about brain
function.  And I agree completely with Richard that physiologically and
anatomically based models are much more likely to do so.  We ourselves have
built and "mined" many such models.  However, it is very important that a
clear distinction be made between models of this type, and those intended
to demonstrate a previously proposed functional idea using a mix of
convenient "neurobiological-like" structures and mechanisms.  There is
nothing wrong with such demonstration models, it is just not appropriate to
claim that they originated the ideas that they were actually designed to
demonstrate.


Jim Bower

           ***************************************
                       James M. Bower
                     Division of Biology
                     Mail code:  216-76
                           Caltech
                     Pasadena, CA 91125
                      (626) 395-6817
                      (626) 795-2088 FAX

      WWW addresses for:
        laboratory                 http://www.bbb.caltech.edu/bowerlab
        GENESIS:                   http://www.bbb.caltech.edu/GENESIS
        science education reform   http://www.caltech.edu/~capsi and
				   http://www.nas.edu/rise/examp81.htm

	J. Computational Neuroscience  http://www.bbb.caltech.edu/JCNS/
	Annual CNS meetings	http://www.bbb.caltech.edu/cns-meetings