Effects of adding inhibitory synaptic input.

(A) shows the effect of increasing I_ratio to 0.5 from 0 on the ISI distributions generated by the HH model at 2.3 and 9 spikes/s (R_epsc was adjusted to 694 and 1304 Hz to achieve firing rates of 2.3 and 9 spikes). Model distributions (pink; I_ratio = 0.5, g_BK = 1) are superimposed on ISI distributions from the reference data in Fig 1 (blue). Increasing I_ratio increases the number of short ISIs, and the model ISI distribution no longer matches the reference data. (B) shows the effect of increasing g_BK to 3.2 mS/cm², with R_epsc adjusted to 694 and 1290 Hz to achieve firing rates of 2.3 and 9 spikes/s. ISI distributions from the adjusted model (purple; I_ratio = 0.5, g_BK = 3.2) are superimposed on ISI distributions from the reference data in Fig 1 (blue). By increasing g_BK, a good fit can again be obtained. (C) shows the ‘average spike waveform’ for three different runs of the model–I_ratio = 0 in green (from Fig 6B), I_ratio = 0.5, g_BK = 1 in pink, and I_ratio = 0.5, g_BK = 3.2 in purple. Increasing I_ratio results in an attenuation of the observed HAP, which can be reversed by increasing g_BK, restoring a good fit to the in vivo reference data.