Figure 3
Shunting has a much greater impact on depolarization than it does on firing rate. These data are based on simulations in the model neuron with Hodgkin-Huxley (HH) channels removed so as to prevent spiking and thereby allow measurement of the underlying depolarization. Yellow shading shows suprathreshold voltages. α = 1. Unlike the nearly linear f out-f exc curves seen in Figure 2, the depol-f exc curves with inhibition (colored) are clearly sublinear (i.e. bend downwards). This sublinearity is not seen in the depol-f exc curve without inhibition (black). At low f exc, depolarization is paradoxically enhanced by inhibitory input with E anion = -50 and -45 mV (i.e. the yellow and orange curves lie above the black curve on the left side of the graph) but, because of the sublinearity in those curves, at high f exc, depolarization is reduced by inhibitory input (i.e. the yellow and orange curves lie below the black curve on the right side of the graph; arrow) even if that reduction is less than that for inhibition with E anion = -70 mV.