Figure 3.

Short-term plasticity changes during development. A, Illustration of complex waveforms from a P7 rat showing synaptic facilitation at short intervals (left), depression at intermediate intervals leading to a postsynaptic failure (middle), and recovery from depression at long intervals (right). Symbols above the waveforms refer to events shown in B. B, Dependence of eEPSP size on interevent interval. Red dots show individual suprathreshold eEPSP amplitudes, purple dots show subthreshold eEPSP amplitudes, and individual squares, triangles, and inverted triangles refer to examples shown in A. Green symbols show binned averages with SD, and black circles indicate the fit with an STP model with both facilitation and depression. Fit parameters were as follows: amplitude 2.0 mV; 95% facilitation per AP, decaying with a time constant of 125 ms; and 38% depression per AP, decaying with a time constant of 1.0 s. The fit could account for 71% of the variance in the eEPSP amplitudes. C, As in B, except the recording was from a P11 animal. Fit parameters were as follows: amplitude 0.6 mV; 62% facilitation per AP, decaying with a time constant of 12.7 ms; and 2.9% depression per AP, decaying with a time constant of 4.4 s. The fit could account for 32% of the variance in the eEPSP amplitudes. D, As in B, except the recording was from a P26 animal. Fit parameters were as follows: amplitude 1.25 mV; 11% facilitation per AP, decaying with a time constant of 11.5 ms. There was no depression. The fit could account for 5.2% of the variance in the eEPSP amplitudes.