Synaptic plasticity in the hippocampus requires activity-dependent gene expression. We have therefore profiled gene expression in area CA1 following the induction of an electroshock-evoked maximal seizure. Using cDNA microarrays, the differential expression of ≈ 9000 cDNAs was examined. In situ hybridization on 14 transcripts that showed strongest modulation in the microarray screen (1.8–2-fold) confirmed the differential expression of a single gene that encodes for the nuclear hormone receptor NGFI-B (Nur77, N10). Although this gene is only modestly up-regulated (≈ 2-fold) in area CA1, in situ hybridization revealed that maximal seizures induce a marked (≈ 12-fold) up-regulation of NGFI-B in the dentate gyrus. These data support the notion [French et al. (2001) Eur. J. Neurosci., 13, 968–976] that CA1 pyramidal neurons are more refractory than granule cells of the dentate gyrus with respect to activity-dependent gene transcription. Furthermore, our results argue against a large cohort of activity-dependent genes in area CA1.