Noise Induced Spiral Waves in Astrocyte Syncytia Show Evidence of Self
Organized Criticality.
PETER JUNG, ANN CORNELL-BELL, KATHLEEN SHAVER MADDEN, AND FRANK MOSS.
School of Physics, Georgia Institute of Technology, Atlanta, GA 30332
Viatech Imaging, Ivoryton, CT 06442, Foundation for International Nonlinear
Dynamics, Bethesda, MD 20816, Center for Neurodynamics, University of
Missouri, St. Louis, MO 63121..
APStracts 4:312N, 1997.
ABSTRACT
Long range (a few centimeters), long lived (many seconds), spiral chemical
waves of calcium ions (Ca2+) are observed in cultured networks of glial cells
for normal concentrations of the neurotransmitter Kainate. A new method for
quantitatively measuring the spatio-temporal size of the waves is described.
This measure results in a power law distribution of wave sizes, meaning that
the process which creates the waves has no preferred spatial or temporal (size
or lifetime) scale. This power law is one signature of self organized critical
phenomena, a class of behaviors found in many areas of science. The
physiological results for glial networks are fully supported by numerical
simulations of a simple network of noisy, communicating threshold elements. By
contrast, waves observed in astrocytes cultured from human epileptic foci
exhibited radically different behavior. The background random activity, or
“noise”, of the network is controlled by the Kainate concentration. The mean
rate of wave nucleation is mediated by the network noise. However, the power
law distribution is invariant, within our experimental precision, over the
range of noise intensities tested. These observations indicate that spatially
and temporally coherent Ca2+ waves, mediated by network noise may play and
important role in generating correlated neural activity (waves) over long
distances and times in the healthy vertebrate central nervous system.
Received 1997; accepted in final form 1997.
APS Manuscript Number J.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 14 November 1997