  The brain can be understood as a collection of interacting neuronal
oscillators, but the extent to which its sustained activity is due to coupling
among brain areas is still unclear. Here we study the joint dynamics of two
cortical columns described by Jansen-Rit neural mass models, and show that
coupling between the columns gives rise to stochastic initiations of sustained
collective activity, which can be interpreted as epileptic events. For large
enough coupling strengths, termination of these events results mainly from the
emergence of synchronization between the columns, and thus is controlled by
coupling instead of noise. Stochastic triggering and noise-independent
durations are characteristic of excitable dynamics, and thus we interpret our
results in terms of collective excitability.
