Figure 4.

Top: asymptotic phase shift between two close isochrons in false colors from 0 to $2\pi$, when an instantaneous perturbation is made on the Wilson-Cowan oscillator. Bottom left: perturbations of same intensity made at two different phases ${\phi }_1$ and ${\phi }_2$ on the limit-cycle of the Wilson-Cowan oscillator. Bottom right: value of the period of the limit-cycle in false colors depending on the values of the parameters ${\tau }_x$ and ${\tau }_y$ from 3.5 to 7.