Figure 7.

AT mice exhibited normal basal synaptic neurotransmission but a decreased PPF ratio and attenuated LTP in the CA1 area of hippocampal slices compared with WT littermates. a, Left, A family of representative voltage traces of fEPSPs in the CA1 area of WT or AT hippocampal slices evoked by different stimulation intensities on the Schaffer collateral and commissural fibers. Right, I-O of the fEPSP. The fiber valley was binned with an interval of 0.2 mV. There were no significant differences in the I-O curves between the genotypes (WT: n = 14 slices from 5 mice; AT: n = 14 slices from 6 mice). b, Comparison of PPF ratio between AT and WT littermates. Left: Representative traces of paired pulse stimulation with 20 ms interval from WT and AT littermates, respectively. Right, The PPF ratio is significantly higher in WT mice than AT mice (WT: 59.3 ± 11.3%, n = 12 slices from 5 mice; AT: 25.7 ± 6.9%, n = 14 slices from 6 mice; unpaired Student's t test, p = 0.02). c, AT mice exhibited decreases in the amplitude of LTP in the CA1 area of hippocampal slices compared with WT littermates. Left, Representative voltage traces of fEPSP are superimposed before (a) and after (b) LTP induction by high-frequency stimulation of the Schaffer collateral and commissural fibers (100 Hz, 1 s, 4 trails, 20 s interval). Right, Each fEPSP slope was normalized to that just before the high-frequency stimulation and plotted as a function of recording time. The magnitude of LTP during the maintenance phase in WT slices is significantly larger than that in AT slices (WT: 234.6 ± 23.8%, n = 14 slices from 5 mice; AT: 164.3 ± 12.7%, n = 14 slices from 6 mice; 2-tailed unpaired Student's t test, p = 0.02).