Noise induces oscillation in the two weakly coupled subgroups of the suprachiasmatic nucleus

In mammals, the main clock regulating the circadian rhythms is located in the suprachiasmatic nucleus (SCN) of the brain. The SCN is composed of about 20,000 synchronized neuronal oscillators and can be divided into two subgroups, named the ventrolateral part (VL) and the dorsomedial part (DM). The circadian rhythms of the SCN output depend on the cellular coupling. If the cellular coupling is reduced, the circadian rhythm of the SCN is lost because the rhythms of the individual neurons are lost. In the present study, we examine whether the lost rhythms of the SCN with the reduced coupling can be restored by the intrinsic noise to the neurons. Based on a modified Goodwin model, both the simulations and the analyses show that the rhythms of the SCN can be restored by the noise when the VL and the DM are weakly coupled. Our finding provides a method to restore the lost rhythms of the SCN and shed light on the influence of noise on the collective behaviors of the SCN.