Intracortical microinjections may cause spreading depression and suppress absence seizures

► Drug, saline, and sham microinjections can suppress spike-wave discharges (SWDs). ► Sham microinjections frequently induce cortical spreading depression (SD) wave. ► Long-term suppression of SWDs occurs after microinjections accompanied by SD. ► SD may contribute to effects of intracortical microinjections.