RESUMEN
OBJECTIVE Epileptic networks are char-acterized as two states,seizures or more prolonged inter-ictal periods.However,cellular mechanisms underlying the contribution of interictal periods to ictal events remain unclear.METHODS Here,we present the procedure for labeling seizure-activated and interictal-activated neuro-nal ensembles in mouse hippocampal kindling model using an enhanced-synaptic-activity-responsive element.This technique is combined with genetically encoded effectors to characterize and manipulate neuronal ensembles recruited by focal seizures(FS-Ens)and interictal periods(IP-Ens)in piriform cortex,a region that plays a key role in seizure generation.RESULTS Ca2+ activities and histo-logical evidence reveal a disjointed correlation between the two ensembles during FS dynamics.Optogenetic acti-vation of FS-Ens promotes further seizure development,while IP-Ens protects against it.Interestingly,both ensem-bles are functionally involved in generalized seizures(GS)due to circuit rearrangement.IP-Ens bidirectionally modulates FS but not GS by controlling coherence with hippocampus.CONCLUSION This study indicates that the interictal state may represent a seizure-preventing environment,and the interictal-activated ensemble may serve as a potential therapeutic target for epilepsy.