Figure 13.
Power spectral analyses reveal period splitting of Bmal1 dynamics upon changes in parameter values. In brief, the figures show power spectra for numerical simulations which are run for different kR (a) and dR (b) parameter values (shown on the x-axis). Power spectra are calculated for each parameter value and colour coded and thus, each vertical coloured line (i.e. column) from the figure represents one power spectral density plot, for a certain parameter value. Under a certain parameter value threshold, variations in dR and kR do not affect the robust 24 h period. However, when the threshold is reached (kR = 1.38, dR = 0.65), we observe splitting and a second frequency (and its harmonics) appears in the dynamics of RevErb and Bmal1, resulting in toroidal dynamics. Per oscillations remain with a 24 h rhythmicity (data not shown). Results are obtained by numerical integration of the equations as published by Schmal et al. [31]. The white vertical lines indicate default parameters.