Journal of Computational Neuroscience

, Volume 27, Issue 1, pp 81–101

Stability and structural constraints of random brain networks with excitatory and inhibitory neural populations


DOI: 10.1007/s10827-008-0128-0

Cite this article as:
Gray, R.T. & Robinson, P.A. J Comput Neurosci (2009) 27: 81. doi:10.1007/s10827-008-0128-0


The stability of brain networks with randomly connected excitatory and inhibitory neural populations is investigated using a simplified physiological model of brain electrical activity. Neural populations are randomly assigned to be excitatory or inhibitory and the stability of a brain network is determined by the spectrum of the network’s matrix of connection strengths. The probability that a network is stable is determined from its spectral density which is numerically determined and is approximated by a spectral distribution recently derived by Rajan and Abbott. The probability that a brain network is stable is maximum when the total connection strength into a population is approximately zero and is shown to depend on the arrangement of the excitatory and inhibitory connections and the parameters of the network. The maximum excitatory and inhibitory input into a structure allowed by stability occurs when the net input equals zero and, in contrast to networks with randomly distributed excitatory and inhibitory connections, substantially increases as the number of connections increases. Networks with the largest excitatory and inhibitory input allowed by stability have multiple marginally stable modes, are highly responsive and adaptable to external stimuli, have the same total input into each structure with minimal variance in the excitatory and inhibitory connection strengths, and have a wide range of flexible, adaptable, and complex behavior.


Cortical networks Brain dynamics Complex networks Stability analysis Random matrix theory Graph spectra 

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.National Centre in HIV Epidemiology and Clinical Research, School of PhysicsThe University of SydneySydneyAustralia
  2. 2.National Centre in HIV Epidemiology and Clinical Research, Brain Dynamics CenterWestmead Millennium Institute, Westmead Hospital and Western Clinical School of the University of SydneyWestmeadAustralia
  3. 3.Faculty of MedicineThe University of SydneySydneyAustralia
  4. 4.National Centre in HIV Epidemiology and Clinical ResearchSydneyAustralia

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