Effects of adding inhibitory synaptic input.

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