How important are hubs for the generation of extreme events in networks of excitable units?

We study scale-free networks of FitzHugh-Nagumo units whose collective dynamics exhibits rare and recurrent events of high amplitude (extreme events). We investigate which units play a crucial role in the generation of these events. Unexpectedly, we observe that extreme events originate from low-degree units, while high-degree units (hubs) appear to be crucial for the event to engulf the whole network. [ABSTRACT FROM AUTHOR]