Noise delays onset of sustained firing in a minimal model of persistent activity

We report a noise-induced delay of bifurcation leading to persistent synaptically sustained firing in a simple neural circuit. Two neural saddle-node oscillators are coupled with reciprocal excitatory synapses. Increasing synaptic current moves the circuit through a bifurcation into a bistable anti-phase regime. Applying a small random current to both neurons delays the onset of bistability. We analyse the phase plane for the various activity regimes and find that this noise induced mechansim can be related to the structure of asynchronous and synchronous activity states. (C) 2004 Elsevier B.V. All rights reserved.