Figure 5. Variance in the frequency of excitatory inputs.
A, plots of the suppression of PC spiking versus incoming EPSP frequency are shown at three levels of dispersion (d) in the frequency of the excitatory inputs to otherwise homogeneous non-adapting interneurones (see Results for details of how the dispersion was computed; note that there was no change in the mean frequency as the dispersion was increased; the input to the PCs was also dispersed). B, plot of the average suppression of PC spiking, as a function of increasing dispersion in the EPSP input frequency. Synaptic conductances used in this figure: g1 = 11 nS; g2 = 0.4 nS; g3 = 2.1 nS. The number of network simulations (1 s in duration) for this figure was 220. Furthermore, additional network simulations were carried out to explore the effects of frequency variance in the excitatory inputs to interneurones, (i) with different g1, g2 and g3 values; (ii) with (as in the figure) or without dispersion in the frequency of the excitatory inputs to the PCs; and (iii) with the random re-assignment of each individual interneurone to a particular EPSP frequency at each subsequent EPSP (as in the figure), or with the random assignment taking place only once at time zero (in the latter case, therefore, each interneurone received EPSPs at one fixed frequency throughout the simulation run; in either case, however, the mean frequency remained unchanged across the entire interneuronal population). The basic results illustrated in this figure did not change as a function of these parameter changes. The number of these additional network simulations exploring the parameter space was 1068.