Role of feedback loops in the scorpion circadian system

摘要

Scorpions are nocturnal animals whose circadian activity rhythm is entrained via light/dark programs to the median and lateral eyes. Timing of light signals conveyed by the median eyes is modified by feedback from the circadian pacemaker. Using a simulation program, NeuroDynamix, we demonstrated that these median-eye feedback loops cause a preolonged dead Zone in the phase response curve. Also, entrainment by median eyes during simulated T cycles Resulted primarily from brief photoreceptor twilight signals. We propose that feedback loops Reduce entrainment stability, but serve a necessary function by limiting light-generated inputs To the pacemaker to a narrow circadian gate.