Figure 4.

Time resolution of event detection. A, Two experimentally recorded quantal EPSCs from the same experiment were artificially added together with various intervening time intervals ranging from 0 to 5 ms. The event detection procedure was run on these traces to determine the minimum interval required for event disambiguation. B, The procedure correctly discerned the 2 events down to a separation of 0.2 ms in the example shown in A (circles); for shorter intervals, a single event with double amplitude was reported. In another simulation, the second EPSC was scaled following an exponential function of the separation between the two EPSCs, to mimic amplitude occlusion (as detailed in Fig. 6–7). This gave the same time resolution (triangles). C, Group results from 25 experiments as in A indicate detection threshold with separations of 0.2 to 0.3 ms (closed symbols; associated error bars, when visible, indicate ± SEM). D, Associated amplitude measurements from the same experiments (upward triangles: amplitudes of first detected EPSCs; downward triangles, amplitudes of second detected EPSCs, when applicable; note double amplitude of single events for separations of 0–0.15 ms and intermediate amplitudes in 0.2–0.3 ms separation range).