Phase-shift of cellular coupling induces the anti-phase synchronization between the left and right suprachiasmatic nucleus

Abstract

Exposed to the constant light, the master clock located in the bilaterally paired suprachiasmatic nucleus (SCN) above the optic chiasma exhibits three rhythmic behaviors in hamsters. Some hamsters remain or lose circadian rhythms due to synchronization or desynchronization between the SCN neurons, respectively. Interestingly, the other hamsters show a phenomenon called “split”, in which the left SCN and right SCN oscillate with a stable anti-phase. In this paper, a modified Kuramoto model is built to explain these three rhythmic behaviors, where the phase-shift of cellular coupling is taken into account. Three cases of phase-shifts are considered, including that first case exists in all the SCN neurons, second case exists between the left and right SCN, and the last case exists within each group. We found that the phase-shift is able to induce the anti-phase synchronization between the left SCN and right SCN in the former two cases, but eliminate this anti-phase synchronization in the latter case. Our findings provide an alternative explanation for the emergency of the split and shed light on the collective behaviors of the SCN neurons.