title: Heterogeneity induces rhythms of weakly coupled circadian neurons.
abstract: The main clock located in the suprachiasmatic nucleus (SCN) regulates circadian rhythms in mammals. The SCN is composed of approximately twenty thousand heterogeneous self-oscillating neurons, that have intrinsic periods varying from 22 h to 28 h. They are coupled through neurotransmitters and neuropeptides to form a network and output a uniform periodic rhythm. Previous studies found that the heterogeneity of the neurons leads to attenuation of the circadian rhythm with strong cellular coupling. In the present study, we investigate the heterogeneity of the neurons and of the network in the condition of constant darkness. Interestingly, we found that the heterogeneity of weakly coupled neurons enables them to oscillate and strengthen the circadian rhythm. In addition, we found that the period of the SCN network increases with the increase of the degree of heterogeneity. As the network heterogeneity does not change the dynamics of the rhythm, our study shows that the heterogeneity of the neurons is vitally important for rhythm generation in weakly coupled systems, such as the SCN, and it provides a new method to strengthen the circadian rhythm, as well as an alternative explanation for differences in free running periods between species in the absence of the daily cycle.
authors.affiliation: Business School, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Changgui
authors.initials: C
authors.lastname: Gu
authors.affiliation: School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Liang
authors.affiliation: Business School, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Huijie
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden 2300RC, The Netherlands.
authors.forename: Jos H T
authors.initials: JH
authors.lastname: Rohling
mesh_terms: D000818:Animals; D001683:Biological Clocks; D002940:Circadian Rhythm / Q000502:physiology*; D003624:Darkness; D008322:Mammals / Q000502:physiology; D008962:Models, Theoretical; D009415:Nerve Net / Q000502:physiology; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism; D013493:Suprachiasmatic Nucleus / Q000502:physiology*
chemical_list: D009479:Neuropeptides; D018377:Neurotransmitter Agents