Fig. 6: Parameter space exploration for periodic stimulation.
a Schematic representation of the two different scenarios analyzed, constant (left) and periodic (right) stimulation, and the attributes selected in each one. Constant stimulation is a step in ST going from zero to the desired value at t = 0 and periodic stimulations are the adapted variations, sinusoidal, or train of square pulses, indicated in Figs. 4a–c and 4d–e, with frequencies in the range 10−4–101 Hz, resulting in periods in the range 0.1−104 s. For constant stimulation, the attributes are tdec and Pmax. For periodic stimulations, the attributes are TA,max, Amax, TG,max, Gmax (being T the period, T = 1/f). The frequency for which the maximum amplitude/gain is obtained and the corresponding maximum amplitude/gain is indicated over the plots as fA,max, fG,max, and Amax, Gmax. b Results from the parameter sampling with 5,000 parameter sets. Sinusoidal stimulation was applied as ST(t) = Smax(1+0.5sin(2πft))/1.5, then adapted as explained in Fig. 4 (and the text). Train of square pulses stimulation was applied as ST = Smax for nT < t <(n+0.5)T, ST = 0 for (n+0.5)T < t <(n + 1)T, n is a natural number, implying the input in the first half of the period. From the 5,000 parameter set values analyzed, 149 resulted in signal termination and all of them exhibited a maximum in the gain versus frequency plot, and also in the amplitude versus frequency plot but for sinusoidal stimulation only. Scatter plots relating an attribute from the output to periodic stimulation and an attribute from the output to step stimulation. The Pearson coefficient for each case is indicated over the plot. Left plots are TG,max and TA,max versus tdec, right plots are Gmax and Amax versus Pmax. Scatter plots in dark yellow correspond to sinusoidal stimulation and scatter plots in cyan correspond to square stimulation.
