Spiking control by means of "phase feedback" in FitzHugh-Nagumo circuits

We investigate the feedback control of a periodically driven FitzHugh-Nagumo circuit (FHN), which displays both spiking and non-spiking behaviors in chaotic or periodic regimes. The simple high pass filter (washout filter) is compared with an all pass filter which only affects the phase characteristics of the input signal. Experimental measurements performed on the electronic implementation of the FHN are in good agreement with numerical simulations. Apart a small difference in their amplitude corrections that remain in both cases within a few percent with respect to the unperturbed spiking signal, we prove the key role of the phase characteristics of the two filters in achieving control.