## Changes in EPSC parameters have little effect on the ISI distribution.

We investigated how changes to the EPSC parameters affect the ISI distribution in the HH model when the spike rate is kept constant at 9 spikes/s. (**A)** Increasing the EPSC magnitude (Δ_{epsc}) slightly increases the number of short ISIs, shifting the distribution to the left, with a small decrease in the height of the mode. Plotted distributions are for EPSP magnitudes of ~ 1, 2, 3, and 4 mV (darkest to lightest). The changes in EPSPs that result from the changes in *k*_{epsc} are plotted on the right. EPSC rates (*R*_{epsc} = 2920, 1294, 774 and 526 Hz respectively) were adjusted to achieve a firing rate of 9 spikes/s. **(B)** Increasing the EPSC time-constant (τ_{epsc}) very slightly increases the number of short ISIs, shifting the distribution to the left, with a small decrease in the height of the mode. Plotted distributions are for τ_{epsc} = 1.1, 2.2, 3.3, and 4.4 ms (yellow to dark red). The changes in EPSPs that result from the changes in τ_{epsc} are plotted on the right. EPSC rates (*R*_{epsc} = 2685, 1220, 774, and 567 Hz respectively) were adjusted to achieve a firing rate of 9 spikes/s.