EEG Dynamics: BBS Call for Commentators

Below is the abstract of a forthcoming target article on: BRAIN DYNAMICS, EEG & NEURAL NETS by JJ Wright & DTJ Liley This article has been accepted for publication in Behavioral and Brain Sciences (BBS), an international, interdisciplinary journal providing Open Peer Commentary on important and controversial current research in the biobehavioral and cognitive sciences. Commentators must be current BBS Associates or nominated by a current BBS Associate. To be considered as a commentator for this article, to suggest other appropriate commentators, or for information about how to become a BBS Associate, please send email to: bbs(a)ecs.soton.ac.uk or write to: Behavioral and Brain Sciences Department of Psychology University of Southampton Highfield, Southampton SO17 1BJ UNITED KINGDOM http://cogsci.ecs.soton.ac.uk/~harnad/bbs.html gopher://gopher.princeton.edu:70/11/.libraries/.pujournals ftp://ftp.princeton.edu/pub/harnad/BBS To help us put together a balanced list of commentators, please give some indication of the aspects of the topic on which you would bring your areas of expertise to bear if you were selected as a commentator. An electronic draft of the full text is available for inspection by anonymous ftp (or gopher or world-wide-web) according to the instructions that follow after the abstract. ____________________________________________________________________ DYNAMICS OF THE BRAIN AT GLOBAL AND MICROSCOPIC SCALES: NEURAL NETWORKS AND THE EEG. J.J. Wright and D.T.J. Liley Mental Health Research Institute Parkville Victoria 3052, Australia jjw(a)cortex.mhri.edu.au Swinburne Center for Applied Neuroscience Hawthorne, Victoria 3122 Melbourne, Australia KEYWORDS: chaos, EEG simulation, electrocorticogram, neocortex, network symmetry, neurodynamics. ABSTRACT: There is some complementarity of models for the origin of the electroencephalogram (EEG), and neural network models for information storage in brain-like systems. From the EEG models of Freeman, Nunez, and the author's group, we argue that the wave-like processes revealed in the EEG exhibit linear and near-equilibrium dynamics at macroscopic scale, despite extremely nonlinear, probably chaotic, dynamics at microscopic scale. Simulations of cortical neuronal interactions at global and microscopic scales are then presented. The simulations depend on anatomical and physiological estimates of synaptic densities, coupling symmetries, synaptic gain, dendritic time constants and axonal delays. It is shown that the frequency content, wave velocities, frequency/wavenumber spectra and response to cortical activation of the electrocorticogram (ECoG) can be reproduced by a "lumped" simulation treating small cortical areas as single functional units. The corresponding cellular neural network simulation has properties which include those of attractor neural networks proposed by Amit, and Paresi. Within the simulations at both scales, sharp transitions occur between low and high cell firing rates. These transitions may form a basis for neural interactions across scale. To maintain overall cortical dynamics in the normal low firing-rate range, interactions between the cortex and subcortical systems are required to prevent runaway global excitation. Thus the interaction of cortex and subcortex via cortico-striatal and related pathways, may partly regulate global dynamics by a principle analogous to adiabatic control of artificial neural networks -------------------------------------------------------------- To help you decide whether you would be an appropriate commentator for this article, an electronic draft is retrievable by anonymous ftp from ftp.princeton.edu according to the instructions below (the filename is bbs.wright). Please do not prepare a commentary on this draft. Just let us know, after having inspected it, what relevant expertise you feel you would bring to bear on what aspect of the article. ------------------------------------------------------------- These files are also on the World Wide Web and the easiest way to retrieve them is with Netscape, Mosaic, gopher, archie, veronica, etc. Here are some of the URLs you can use to get to the BBS Archive: http://www.princeton.edu/~harnad/bbs.html http://cogsci.ecs.soton.ac.uk/~harnad/bbs.html gopher://gopher.princeton.edu:70/11/.libraries/.pujournals ftp://ftp.princeton.edu/pub/harnad/BBS/bbs.wright ftp://cogsci.ecs.soton.ac.uk/pub/harnad/BBS/bbs.wright To retrieve a file by ftp from an Internet site, type either: ftp ftp.princeton.edu or ftp 128.112.128.1 When you are asked for your login, type: anonymous Enter password as queried (your password is your actual userid: yourlogin(a)yourhost.whatever.whatever - be sure to include the "@") cd /pub/harnad/BBS To show the available files, type: ls Next, retrieve the file you want with (for example): get bbs.wright When you have the file(s) you want, type: quit ---------- Where the above procedure is not available there are two fileservers: ftpmail(a)decwrl.dec.com and bitftp(a)pucc.bitnet that will do the transfer for you. To one or the other of them, send the following one line message: help for instructions (which will be similar to the above, but will be in the form of a series of lines in an email message that ftpmail or bitftp will then execute for you). -------------------------------------------------------------