Figure 9.

System’s dynamics under photoperiod changes. (A) The calculated synchronization level Rsyn in both the core and the shell decrease as the photoperiod increases. (B) The reduced synchronization results in lower ensemble average amplitudes of the core and the shell under longer photoperiods, which further leads to the decrease in corticosterone amplitude. (C) The core exhibits a phase delay as the photoperiod increases, while the phase changes of the shell and the HPA axis are nonmonotonic. (D–F): The circadian dynamics of the representative components of the core the shell, and the HPA axis under different photoperiods. The phase and amplitude relationships are consistent with the observations in Figures (A–C).