Optical electrocorticogram (OECoG) using wide-field calcium imaging reveals the divergence of neuronal and glial activity during acute rodent seizures

•Wide-field calcium imaging can serve as an optical electrocorticogram (OECoG).•Simultaneous neuronal and glial ictal activity can be recorded by using OECoG.•Glial waves were initiated by the seizure onset.•Ictal glial activity propagated further than neuronal activity.•Neuronal ictal events lasted longer than glial waves.

The role of glia in epilepsy has been widely debated. Using in vivo bulk loading of calcium dyes, we imaged neuronal and glial activity in an acute pharmacologic rodent model of neocortical seizures. Optical calcium-based ECoG maps revealed that neuronal waves propagated rapidly and remained mostly confined to the seizure focus. Glial waves were triggered by ictal onset but propagated slowly in a stereotypical fashion far beyond the seizure focus. Although related at their onset, the divergence of these two phenomena during seizure evolution calls into question their interdependence and the criticality of the role of glia in seizure onset and neurovascular coupling.This article is part of a Special Issue entitled “Status Epilepticus”.