Two different interictal spike patterns anticipate ictal activity in vitro

► 4AP in vitro induces two types of ictal events in the entorhinal cortex. ► They are preceded by an isolated discharge (ISID) or by frequent discharges (FPID). ► Glutamatergic receptor antagonists reduced FPIDs but did not influence ISIDs. ► HFOs (80-500 Hz) occur more frequently during ISIDs as compared to FPIDs. ► Ictal onset patterns resemble those seen in vivo in low-voltage fast-onset seizures.