A, example of fEPSP recordings before (dashed lines) and 60 min after LTD induction (continuous lines) in the CA1 area of acutely prepared hippocampal slices from 10- to 14-day-old homozygous D36 or litter-matched WT mice. B, LTD was induced by a stimulus train of 1 Hz for 15 min (bar). Plotted are averages of the initial slope of the fEPSPs of multiple recordings for each time point normalized for each recording (100% equals the average of the recorded fEPSP slopes during the 15 min interval immediately preceding LTD induction). LTD is substantially decreased in D36 mice (90 ± 2% mean ± s.e.m. at 70–75 min, ○) versus littermate-matched WT mice (62 ± 3% at 70–75 min, •). This decrease is highly significant (P < 0.0001, t test). C, LTP was induced in slices from 3-week-old D36 or litter-matched WT mice by one train of 100 stimuli at 100 Hz (arrow). Five minutes later depotentiation was induced by one train of 900 stimuli at 1 Hz (black bar). The initial potentiation and the subsequent depotentiation were comparable in D36 and littermate-matched WT mice (D36 mice: 130 ± 3% at 5 min; 101 ± 3% at 75–80 min, ○; WT mice: 134 ± 4% at 5 min; 101 ± 4% 75–80 min, •). The 100 Hz tetanus reliably induces LTP in 3-week-old mice in our hands (Lu et al. 2007).