In contrast with the slices from young mice, LTP levels in the slices from older 1d2d-PSD-95-EGFP KI and WT mice induced by the high-frequency stimulus were indistinguishable (WT: 167.9 ± 15.1%, n = 7; KI: 182.6 ± 15.6%, n = 6, at 60 min after tetanus Figure 5A). This evidence concerns the gene DLG4 and tetanus.