The decay phase of 137 EPSPs were fitted with one exponential. One distinct mode representing class 1 EPSPs is present in the histogram with a mean at 2.1 ms. Exemplars of the single exponential fits of classes 1–6 EPSPs, illustrate that these EPSPs will best be fitted by more than one exponential, except for the class 3 EPSP, which is well fitted with one exponential. Dots mark the points of divergence between the trace and the fit. EPSP classes 1, 4, 5 and 6 represent the majority of all EPSPs recorded. The width of the decay time windows associated with all EPSP classes, 1–6, are indicated by bars below the histogram. Horizontal calibration bar, 10 ms, applies to all classes. Vertical calibration bars, 2 mV for class 3 and 4 mV for all other classes.