Probability distributions of the difference in the dynamical variables immediately after the last spike of the input train

for different values of the average input ISI, which increases along the rows (0.1, 0.2, 0.5, 1, 2, 3, 5). The isolines of the cumulative discriminability as a function of

are represented as white lines. Isolines are drawn for discriminability values of 1, 2, 4, 8, 32 and 64, starting from the center. Probability densities are normalized to the peak value in each plot. For each value of

, which increases along columns, the three higher

values are shown (the higher

value is shown in red). For high frequency inputs, the dynamic encoding mechanism plays little role, and the

points accumulate along a line. As the input frequency decreases, the input trains interact with the intrinsic oscillatory dynamics and the

points distribute over a larger area in the

phase space. Note that the input mean ISI that results in the greatest spread of points in the

phase space, which corresponds to the optimal input frequency for dynamic encoding, decreases with increasing

. In addition to this, increasing

results in a greater average discriminability for

points in a circular region centered at the origin, denoting a greater discriminability based on the free evolution of the model neuron.

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