Figure 3

(A) Time histories of the \(2TR\)-periodic states in system (1). Active tone A and B intervals are shown by blue and red bars, respectively. Units’ threshold crossings are shown by green dots. (B) The total number of threshold crossings for both units is shown in greyscale for simulated trajectories at varying PR and df (black =2, lightest gray =4 crossings). Parameters PR and df in panel (A) are shown by white dots in panel (B). Yellow and purple crosses are the experimentally detected coherence and fission boundaries, respectively (data replotted from Fig. 2 in [47], digitalized using the software WebPlotDigitizer [48]). The remaining parameters are \(a=2\), \(b=2.8\), \(c=5.5\), \(D=0.015\), \(\theta =0.5\), \(TD=0.022\), \(\tau _{i}=0.25\), \(\tau =0.025\), \(\theta =0.5\) and \(m=6\). Simulations are performed using dde23 in Matlab with absolute and relative tolerances set to 10⁻⁷. Initial conditions on the interval \([-D,0]\) are specified as a constant vector function equal to \([1,0,1,0]\)