Figure 5.  Short-term plasticity is altered during synaptic
depression. A:Paired pulses applied with 50 ms interstimulus
intervals (ISI) to the auditory pathway in rat brain slices
revealed paired pulse facilitation (ppf). Typical EPSC traces
evoked by paired pulses (with EPSC1 and EPSC2) in a PnC giant
neuron under control conditions (control) and during synaptic
depression (SD), immediately after application of a 100 burst
sequence. Scale bars: vertical 30 pA, horizontal 30 ms. B: Mean
EPSC1 amplitudes before (control) and during synaptic depression
(SD). Measurements were repeated 10 times at 1 Hz and traces
were subsequently averaged for each cell. The absolute EPSC1
amplitude was not changed by synaptic depression (n = 17). C:
Mean paired pulse ratio (EPSC2/EPSC1) of paired pulses before
(control) and during synaptic depression (HSD). The paired pulse
ratio was significantly reduced during synaptic depression (n =
17). Error bars indicate S.E.M. D: Analysis of the amplitudes of
the first response (gray l