Differences in intrinsic amplitudes of neuronal oscillators improve synchronization in the suprachiasmatic nucleus

In mammals, a main clock located in the suprachiasmatic nucleus (SCN) regulates the ∼24 h rhythms of behavioral and physiological activities exposed to a natural 24 light-dark cycle or even under constant darkness. The rhythms originate from self-sustained oscillations of the SCN neurons, which differ in both intrinsic periods and intrinsic amplitudes. The intrinsic periods and the intrinsic amplitudes were found to be bound to specific regions in the previous experiments. In particular, neurons of smaller amplitudes and larger periods are located in a ventrolateral part, and neurons of larger amplitudes and smaller periods are in a dorsomedial part. In the present study, we examined the effects of the differences in the intrinsic frequencies and the differences in the intrinsic amplitudes of neuronal oscillators on the synchronization, respectively. We found that the differences in the intrinsic frequencies weaken the synchronization, whereas the differences in the intrinsic amplitudes strengthen the synchronization. Our finding may shed light on the effects of the heterogenous properties of individual neurons on the collective behaviors of the SCN network and provide a way to enhance the synchronization.