Long-term potentiation (LTP) evoked at the CA3-CA1 synapse in 3- and 18-month-old Polµ^−/− and wild-type mice.

<p>(<b>A</b>) LTP induction in representative 3-month-old control (black circles) and Polµ^−/− (white circles) mice. LTP was evoked in CA1 pyramidal cells by HFS of ipsilateral Schaffer collaterals (five 200 Hz, 100 ms trains of pulses at a rate of 1/s. This protocol was presented 6 times in total, at intervals of 1 min). The fEPSP is given as a percentage of the baseline (100%) slope. Records in the inset were collected at the indicated (1–3) times. (<b>B</b>) Mean ± SEM fEPSP values 1–15 min before (baseline), and 15–30 min (1), 105–120 min (2), and 24 h (3) after HFS for 3-month-old control (black bars) and Polµ^−/− (white bars) animals. No significant differences were observed between LTP evoked in these two groups of animals (<i>P</i> = 1, two-way ANOVA). (<b>C, D</b>) A similar set of data collected from 18-month-old wild-type (black triangles and bars) and Polµ^−/− (white triangles and bars) mice. Note that, in contrast with Polµ^−/− mice, 18-month-old controls presented a non-significant increase in fEPSP slopes after the presentation of the HFS protocol (*<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001, two-way ANOVA).