Figure 6. I_h-mediated hyperpolarization broadens the integration time window in an integrate-and-fire neuronal model.

(a) Successive activation of excitatory and inhibitory conductances in a simple integrate-and-fire neuron was used to produce an EPSP–IPSP sequence similar to that observed experimentally. (b) Simulation of two pathways activated with different delays (see Methods) resulted in a narrow integration time window. Synaptic strength was adjusted so that the peak probability of action potential generation remained at 50%. (c) Removal of I_h from the dendrites hyperpolarized the modelled neuron by 10 mV. The graph shows spike probability at different intervals between stimuli with (open bars) and without I_h (red bars) in the modelled neuron. (d) The effect of I_h removal was abolished when the neuronal soma was repolarized by DC injection (open bars: control with I_h, blue bars: no I_h repolarized). Data are presented as means of 30 rounds of simulations, error bars represent s.e.m.