Fig 3. The phase of output spiking depends on synaptic configuration.

The traces in Subfigure A were produced by forming histograms of postsynaptic spiking in response to 1 Hz-modulated population inputs for different synaptic configurations with depressing synapses. Spike times from each cycle of the input modulation in all cells in all runs with a particular synaptic configuration were binned in 1.8° phase bins. The histograms were then smoothed using a 20 sample moving average, and normalised. The dotted line shows the phase of the input modulation; since the modulation is defined as a sine wave rather than a cosine wave, the phase of its peak is at 90°, whereas the output spiking peaks at an earlier phase, and therefore has a phase lead. The dashed line makes it clear that the largest output phase lead (the blue trace crosses the dashed line at approximately 90° to the left of where the input modulation crosses the dashed line) is for M = 1 and the smallest (approximately 40°) for M = 512. Subfigure B shows scatter plots of each pair of phase and normalised spike count used to form the data shown in subfigure A; colored lines indicate the mean phase, in good correspondence with the crossings of the dashed line shown in A. The dotted black line shows that the phase of the input modulation is 90°, as in subfigure A.