Direct translation as "Взрыв" sounds extremely wrong when talking about neural bursting. Some neurons can fire a number of spikes (burst of spikes) in a short period of time, followed by a period of quiescence. This phenomenon is called bursting. I have trouble finding a proper translation for the term.
UPD: thanks for the suggestions. I'll try to resolve the confusion. I'm referring to a specific dynamical regime of a single neuron, which happens to be called "bursting", as described here: http://www.scholarpedia.org/article/Bursting. It's different from the notion of an abstract abrupt increase in the (possibly collective) neural activity, which, I agree, can be nicely translated as "всплеск"/"вспышка".