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Introduction Epileptic seizures induce aberrant adult hippocampal neurogenesis (AHN), yet how varying seizure intensities affect this process and associated memory functions remains unclear. Methods Here we administered systemically a low (5 mg/kg) or a high (25 mg/kg) dose of kainic acid (KA) to induce acute hyperexcitability of differing severity in mice of both sexes (6 to 8 weeks-old) genetically labeled for Ascl1, which allowed to follow progenitor cells and their progeny in the dentate gyrus (DG). We recorded EEG, assessed spatial and contextual fear memory, and analyzed adult-born granule cells (abGCs) 32 days post-treatment. Results High-dose KA produced more severe and prolonged seizures, increased mature abGCs with altered laminar positioning, and elevated dendritic spine density, whereas low-dose KA induced presynaptic bouton enlargement. Both doses impaired spatial location recognition but spared contextual fear memory. Discussion These findings reveal that acute seizure severity differentially modulates morphological and synaptic features of abGCs and selectively disrupts hippocampal-dependent spatial memory, indicating that hyperexcitability exerts qualitative effects on neurogenesis and cognitive function.
López-Ibarra et al. (Tue,) studied this question.