Figure 5.

Short-term depression (STD) and its recovery of the PIR-MD synapse. (A) Example traces of repetitively (5, 10 and 50 Hz) stimulated EPSCs. (B) The normalized amplitudes of EPSCs during trains of stimuli at 1–50 Hz (mean ± SEM (unidirectional), n = 8). The depression is fitted monoexponentially. (C) Failure rate of stimulation. Symbols as in (A) (mean ± SD (unidirectional), n = 8). (D) The synapses (n = 5) were first stimulated 25 times at 50 Hz to deplete the vesicle pool. Following a variable interval an identical test train was applied. The recovery rate is calculated as the amplitude of the first EPSC in the test train (EPSC₂₆) normalized by the first EPSC in the depression train (EPSC₁). Outliers, defined by the 1.5× the interquartile range method, were dismissed. The pooled data is fitted by a monoexponential function (τ = 1.34 ± 0.29 s). (E) Back extrapolation per synapse of the readily releasable pool (RRP) from the linear phase of the cumulative amplitude plot (data shown for one synapse).