Long-term potentiation (LTP) is impaired in 9-month old Hu97/18 CA1.

<p>(A) Representative fEPSP traces from hippocampal slices of 9-month old Hu18/18 and Hu97/18 mice in response to two 0.1 ms pulses separated by 100 ms. fEPSPs were recorded in CA1 stratum radiatum during stimulation of the Schaffer collateral pathway. (B) Paired pulse facilitation (PPF) was measured by dividing the slope of the second response to that of the first and was expressed as percent increase. PPF was significantly lower in Hu97/18 CA1 (Hu18/18 n = 8, Hu97/18 n = 6). (C) fEPSPs were normalized to a 10-minute baseline period prior to high-frequency stimulation (HFS; 100 Hz for 1 s×3, 10 s inter-train interval). LTP was easily obtained in hippocampal slices from Hu18/18 mice (n = 6) but showed severe impairment in slices from Hu97/18 mice (n = 6). Representative traces before (black) and 50–60 minutes after (grey) HFS are shown. ***p<0.0001, t-test of average % above baseline 50–60 minutes post-HFS. (D–F) Paired pulse facilitation (D,E) and LTP (F) graphs as above but conducted in slices from 3-month old animals. n = 6 for each genotype for both (E) and (F).