Figure 1.

An E–I network acts as a coherence filter. Four different pulses are delivered to the E‐cell after an inhibitory spike. V is the membrane potential of a quadratic integrate and fire neuron (Latham et al., 2000) recovering from inhibition, and s is the strength of the inhibitory current (as a fraction of peak inhibition). V asymptotes to a stable resting voltage, which increases as s decays. The threshold voltage (above which V spikes) decreases with s. When s = 0.2, the stable resting voltage meets the threshold voltage, and the cell spikes. The lower branch of the solid parabola is the stable resting voltage, and the upper branch is the threshold voltage. During a square pulse of height 0.2 (purple, cyan), the resting and threshold voltages shift to the dashed parabola. The membrane potential asymptotes to the new resting voltage and returns after the pulse, so a 6‐ms‐long pulse has the same effect as a 2‐ms‐long pulse. During a square pulse of height 0.4, the resting and threshold voltages shift to the dotted parabola – the leak current is overpowered, and the resting and threshold voltages disappear. A 2‐ms‐long pulse of this height (red) evokes a spike even though it carries less current than the longer, shorter pulse. However, at very short time scales, the amount of current can still be a limiting factor – a 1‐ms‐long pulse of height 0.6 (blue) does not carry enough current to reach a high voltage before the pulse is over.