Figure 2.

Electrophysiological properties of hippocampal CA1 pyramidal neurons of the RhoB^−/− mouse. A, Basal synaptic transmission was unaffected in the CA1 region of RhoB^+/+ (+/+) hippocampal slices (black squares) when compared with RhoB^−/− (−/−) slices (open circles) as determined by their input/output responses. B, Paired-pulse facilitation was reduced at an interstimulus interval (ISI) of 20 ms in RhoB^−/− compared with RhoB^+/+ mice in the CA1 pyramidal neurons. Representative EPSP traces at 20 ms show the facilitation of the second EPSP compared with the initial response in both RhoB^+/+ and RhoB^−/− animals. C, High-frequency stimulation (100 Hz, 1 s) of the synaptic response in area CA1 (arrow) produced a significant and long-lasting potentiation of the synaptic response in RhoB^+/+ animals. PTP of the response was significantly reduced in RhoB^−/− animals, as was the eLTP. A later phase LTP (60 min post-tetanus) however, was unaffected in RhoB^−/− animals compared with their RhoB^+/+ counterparts. Representative EPSP traces from RhoB^+/+ and RhoB^−/− animals at t = −5 (1), 2 (2), 15 (3), and 60 min (4) show that the early deficit in synaptic potentiation is recovered over time. Data are expressed as mean ± SEM [n = 9–19, *p < 0.05, **p < 0.01: two-way ANOVA followed by Tukey's post hoc analysis at t = 2 min (PTP), t = 15 min (eLTP), t = 60 min (lLTP) compared with t = −5 min (baseline)].