From: IN%"CYBSYS-L@BINGVMB" "Cybernetics and Systems" 17-JAN-1990 18:31:51.34 To: "Peter H. Roosen-Runge" , RICHARD CLARK CC: Subj: Re: Chaos in the brain Received: From BINGVMB(MAILER) by YUSOL with Jnet id 0384 for CS100006@YUSOL; Wed, 17 Jan 90 18:31 EDT Date: Wed, 17 Jan 90 17:18:50 EDT From: CYBSYS-L Moderator <@NEXUS:cybsys@bingvaxu.cc.binghamton.edu> Subject: Re: Chaos in the brain Sender: Cybernetics and Systems To: "Peter H. Roosen-Runge" , RICHARD CLARK Reply-to: Cybernetics and Systems From: CYBSYS_L Moderator >I don't think >anyone is much surprised by the fact we find such phenomena in neurobiology. We should not blithely assume that natural systems are describably in terms of dynamical theory, but I know what you mean. >The interesting question (to me) seems to be: Is chaos useful in any sense >to biological systems? Or is it that the biological systems are such that >chaos "doesn't bother" them? I mean, how does chaos participate (if it >at all) in the biological information processing of the brain? The evidence is very strong that chaos is both necessary and useful for normal nervous activity. I'm mostly drawing from Freeman here, and that is still my primary reference. His claim is that chaos is the natural "background activity" level of neural systems. This is evidenced by all EEG readings and his own research specifically in the olfactory cortices or rabbits. You can calculate the fractal dimension between 4 and 6. This is useful to prevent "entrainment" of neural response, typified by seizures (too regular behavior). Against this background activity (rest state), perceptions stand out as low-dimensional cyclic attractors. This is complex stuff, and I'd strongly advise reading the original by Skarda and Freeman and the excellent series of review articles which followed by neurolgoists, cognitive scientists, etc. (Rene Thom commented). I wrote a review paper on this which I could post, but the originals are better. Bibliography follows. Babloyantz, A, and Salazar, JM: (1985) "Evid.ofChaoticDyn.ofBrn.Act.DuringSleep Cycle", /Physics Letters/, v. 111A Freeman, William J: (1972) "Waves, Pulses and the Theory of Neural Masses", /Progress in THeoretical Biology/, v. 2 (1975) "Mass Action in the Nervous System", Academic Press (1987) "Simulation of Chaotic EEG Patterns", /Biological Cybernetics/, v. 56 Freeman, William J, and Viana Di Prisco, G: (1986) "EEG Spatial Pattern Differentiation w/Discrete Odors Manifests Chaos + Limit Cycle Attractors", /Brain Theory/, ed. G. Palm, Springer-Verlag, Berlin Froehling, H., and et. al., : (1981) "On Determining the Dimension of Chaotic Flows", /Physica/, v. 3D Grassberger, Peter, and Procaccia, I: (1983) "Measuring Strangeness of Strange Attractors", /Physica/, v. 9D Hebb, DO: (1949) "Organization of Behavior", Wiley Skarda, CA, and Freeman, WJ: (1987) "How Brains Make Chaos Into Order", /Behavioral and Brain Sciences/, v. 10 O-----------------------------------------------------------------------------> | Mailing list for Systems and Cybernetics: CYBSYS-L@BINGVMB.BITNET | Moderator Address: cybsys@bingvaxu.cc.binghamton.edu | Systems Science, SUNY Binghamton, Binghamton New York V