Modeling distributed axonal delays in mean-field brain dynamics

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Title Modeling distributed axonal delays in mean-field brain dynamics
Author Roberts, Jacqueline; Robinson, P. A.
Journal Name Physical Review E
Year Published 2008
Place of publication United States
Publisher American Physical Society
Abstract The range of conduction delays between connected neuronal populations is often modeled as a single discrete delay, assumed to be an effective value averaging over all fiber velocities. This paper shows the effects of distributed delays on signal propagation. A distribution acts as a linear filter, imposing an upper frequency cutoff that is inversely proportional to the delay width. Distributed thalamocortical and corticothalamic delays are incorporated into a physiologically based mean-field model of the cortex and thalamus to illustrate their effects on the electroencephalogram (EEG). The power spectrum is acutely sensitive to the width of the thalamocortical delay distribution, and more so than the corticothalamic distribution, because all input signals must travel along the thalamocortical pathway. This imposes a cutoff frequency above which the spectrum is overly damped. The positions of spectral peaks in the resting EEG depend primarily on the distribution mean, with only weak dependences on distribution width. Increasing distribution width increases the stability of fixed point solutions. A single discrete delay successfully approximates a distribution for frequencies below a cutoff that is inversely proportional to the delay width, provided that other model parameters are moderately adjusted. A pair of discrete delays together having the same mean, variance, and skewness as the distribution approximates the distribution over the same frequency range without needing parameter adjustment. Delay distributions with large fractional widths are well approximated by low-order differential equations.
Peer Reviewed Yes
Published Yes
Alternative URI http://dx.doi.org/10.1103/PhysRevE.78.051901
Volume 78
Issue Number 5
Page from 051901-1
Page to 051901-8
ISSN 1539-3755
Date Accessioned 2012-03-15; 2012-04-11T22:21:11Z
Date Available 2012-04-11T22:21:11Z
Research Centre Griffith Institute for Educational Research
Faculty Arts, Education and Law
Subject Specialist Studies in Education
URI http://hdl.handle.net/10072/44430
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1x

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