title: Inhibition causes ceaseless dynamics in networks of excitable nodes.
abstract: The collective dynamics of a network of excitable nodes changes dramatically when inhibitory nodes are introduced. We consider inhibitory nodes which may be activated just like excitatory nodes but, upon activating, decrease the probability of activation of network neighbors. We show that, although the direct effect of inhibitory nodes is to decrease activity, the collective dynamics becomes self-sustaining. We explain this counterintuitive result by defining and analyzing a "branching function" which may be thought of as an activity-dependent branching ratio. The shape of the branching function implies that, for a range of global coupling parameters, dynamics are self-sustaining. Within the self-sustaining region of parameter space lies a critical line along which dynamics take the form of avalanches with universal scaling of size and duration, embedded in a ceaseless time series of activity. Our analyses, confirmed by numerical simulation, suggest that inhibition may play a counterintuitive role in excitable networks.
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts 02115, USA and Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Larremore
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: Woodrow L
authors.initials: WL
authors.lastname: Shew
authors.affiliation: Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Ott
authors.affiliation: Department of Mechanical Engineering, University of New Mexico, Albuquerque, New Mexico 87106, USA.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sorrentino
authors.affiliation: Department of Applied Mathematics, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Juan G
authors.initials: JG
authors.lastname: Restrepo
mesh_terms: D003198:Computer Simulation; D008962:Models, Theoretical; D013269:Stochastic Processes
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