🚀 go-pugleaf

In article <H.eg.UEnwI&3EHKA@wpcst1.phys-chemie.uni-wuerzburg.dbp.de>
kruel@wpcst1.phys-chemie.uni-wuerzburg.dbp.de (Thomas-Martin Kruel) writes:
>   Which are the other authors/groups I should take a look on ?

     Leon Glass has occasionally done work on neurological systems.  Dr.
Ary Goldberger has also done some neurological work, I think.

				Marc R. Roussel
                                mroussel@alchemy.chem.utoronto.ca

     As far as I know at the moment, there has been a lot of theoretical 
speculation in this area, but no real concrete proof of chaos in brain 
activity.  There was an article in Physics Letters a few years ago which 
reconstructed a possbile strange attractor for REM sleep.  You know the work of
Freeman.  Leon Glass wrote an article a few years ago on forced coupled neural 
oscillators in which he concluded that the type of neurons traditionally 
modeled in brain activity does not generate chaos.  David Terman has shown that
there is a small window for chaos in the Fitzhugh-Nagumo equation.  Much work
has been done on bursting (see Nancy kopell/ Bard Ermentrout, John Rinzel, Gail
Carpenter) and amplitude death.  Paul Rapps's work has been reprinted (see
Scientifc American for some references) in Hao Bai-lin, *Chaos* ( first
edition, not second).  Winfree has written some nice articles on coupled 
cellular populations as well.  The best journals to
look through include:  Brain and Behavior Science, Physica D, Journal of
Mathematical Biology, Journal of Mathematical Bioscience, SIAM JOurnal of
Applied Mathematics.
     I would be interested to have a copy of the bibliography when finished.
This is both a hot and cold topic at the moment, in that there is a lot of
theory and computer experimentation, but little emperical proof from humans or
higher vertebrates.  Chaos has been implicated in everything from sense of
smell to schizophrenia in the human brain.  Brain and Behavior Science spends a
lot of time arguing about these topics.  There is a lot of solid work on
dynamical systems applied to neurobiology, but not a lot yet on chaos, in my
opinion.
Donald Casadonte

In article <1992Dec21.182154.4670@magnus.acs.ohio-state.edu>, dcasadon@magnus.acs.ohio-state.edu (Donald J Casadonte) writes:
...
> This is both a hot and cold topic at the moment, in that there is a lot of
> theory and computer experimentation, but little emperical proof from humans or
> higher vertebrates.  Chaos has been implicated in everything from sense of
> smell to schizophrenia in the human brain.  Brain and Behavior Science spends a
> lot of time arguing about these topics.  There is a lot of solid work on
> dynamical systems applied to neurobiology, but not a lot yet on chaos, in my
> opinion.

There is some long-forgotten work using "noise" in a neural system (vertibrate
[dog]) as the basis for building a quantized model of the adrenocortical
feedback control system.  I don't have the cite at hand, but authors include
Donald S. Gann, James Schoeffler, and Lee Ostrander.  Perhaps the first article
was in a volume edited by Mijalo Mesarovic, Proc. of the Nth Systems Syposium,
Cleveland, Ohio, 196X.

The work is/was important in that this may be the first time that a computer
model told the physiologists where to look for a previously-undiscovered neural
pathway (a connection between the median eminance of the hypothalamus and the
adrenal cortex).  Several years later, thanks to horseradish peroxidase, this
pathway was identified and confirmed physiologically.

Dr. Gann is, at last information, now chairing the Department of Surgery at
Brown University.

<OPINION MODE ON>
It seems that the chaos-focussed researchers can't see the forest for the
trees.  The "chaos" that is enamoured for its inherent "beauty" may, in fact,
be conveying a set of signals bearing important information for the control of
some neural process.  Decoding the "chaos" that bears the message is likely to
be less than fruitful  ...  the key is the range of the variation in the
information borne by the "chaos".
<OPINION MODE OFF>

Robin Lake
BP Research
lake@rcwcl1.dnet.bp.com

lakerb@rcwusr.bp.com writes:

><OPINION MODE ON>
>It seems that the chaos-focussed researchers can't see the forest for the
>trees.  The "chaos" that is enamoured for its inherent "beauty" may, in fact,
>be conveying a set of signals bearing important information for the control of
>some neural process.  Decoding the "chaos" that bears the message is likely to
>be less than fruitful  ...  the key is the range of the variation in the
>information borne by the "chaos".
><OPINION MODE OFF>

>Robin Lake
>BP Research
>lake@rcwcl1.dnet.bp.com

The chaos seen in Freeman's work appears to be associated with an
accessible hyperbolic critical point that is used as a starting point for
rapid pattern recognition. Another potential application of chaos is in
controlling a significant, naturally dissipative process at minimum cost.
A third application of chaos is in creating intelligent but unpredictable
behavior. (A good fighter pilot is chaotic.) In yet another context, the
"best" approach to non-zero-sum games with information collection is
inherently chaotic (and hence difficult for purely stimulus/response
systems to generate). Chaos can also be exploited for secure communication
between members of a distributed community. Chaos also resists stylized
attacks better than any periodic process (since the response time
distribution has a continuous Fourier spectrum). 

Cheers,
-- 
Harry Erwin
Internet: erwin@trwacs.fp.trw.com

In article <erwin.725142195@trwacs>, erwin@trwacs.fp.trw.com (Harry Erwin) writes:
> lakerb@rcwusr.bp.com writes:
> 
>><OPINION MODE ON>
>>It seems that the chaos-focussed researchers can't see the forest for the
>>trees.  The "chaos" that is enamoured for its inherent "beauty" may, in fact,
>>be conveying a set of signals bearing important information for the control of
>>some neural process.  Decoding the "chaos" that bears the message is likely to
>>be less than fruitful  ...  the key is the range of the variation in the
>>information borne by the "chaos".
>><OPINION MODE OFF>
> 
>>Robin Lake
>>BP Research
>>lake@rcwcl1.dnet.bp.com
> 
> The chaos seen in Freeman's work appears to be associated with an
> accessible hyperbolic critical point that is used as a starting point for
> rapid pattern recognition. Another potential application of chaos is in
> controlling a significant, naturally dissipative process at minimum cost.
> A third application of chaos is in creating intelligent but unpredictable
> behavior. (A good fighter pilot is chaotic.) In yet another context, the
> "best" approach to non-zero-sum games with information collection is
> inherently chaotic (and hence difficult for purely stimulus/response
> systems to generate). Chaos can also be exploited for secure communication
> between members of a distributed community. Chaos also resists stylized
> attacks better than any periodic process (since the response time
> distribution has a continuous Fourier spectrum). 
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
Do you mean a flat, constant Fourier spectrum.  If so, unless the Chaos
spectrum is non-flat in some other spectral domain, it would seem quite
difficult to convey any information with such a spectrum.

Rob Lake
BP Research

The fourier spectrum need not be flat/constant, as long as it is
continuous. The reason is that this means some element of the system can
respond after an appropriate delay. Otherwise, the system may not be able
to respond _at the appropriate time_. 

Consider a military system that has only two tactics: fight individually
or fight in a solid 10x10 phalanx. If a force deploys as a horde of
individuals, a small team can defeat it piecemeal. If it deploys in
phalanxes, it only controls the ground the phalanxes stand on. In terms of
response time, this system is two-valued, and a threat can penetrate it
between the two values. Only if the force can be tailored to have a
significant amount of combat power at every response time, will it be
successful against an opponent that organizes against its weaknesses. 

I used a military example here because I've considered it in the past,
however there is evidence that the phenomenum of Zipf's Law for the
distribution of sizes of urban settlements is related to this issue. I'm
doing a presentation on this issue next month at the WESS conference at
Georgetown. By that time, I hope to have a better idea of how to present
this.

Cheers,
-- 
Harry Erwin
Internet: erwin@trwacs.fp.trw.com