Business School, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China.
Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, 2300RC Leiden, The Netherlands.
Phys Rev E. 2016 Mar;93(3):032414. doi: 10.1103/PhysRevE.93.032414. Epub 2016 Mar 23.
The dominant endogenous clock, named the suprachiasmatic nucleus (SCN), regulates circadian rhythms of behavioral and physiological activity in mammals. One of the main characteristics of the SCN is that the animal maintains a circadian rhythm with a period close to 24 h in the absence of a daily light-dark cycle (called the free running period). The free running period varies among species due to heterogeneity of the SCN network. Previous studies have shown that the heterogeneity in cellular coupling as well as in intrinsic neuronal periods shortens the free running period. Furthermore, as derived from experiments, one neuron's coupling strength is negatively associated with its period. It is unknown what the effects of this association between coupling strength and period are on the free running period and how the heterogeneity in coupling strength influences this free running period. In the present study we found that in the presence of a negative relationship between one neuron's coupling strength and its period, surprisingly, the dispersion of coupling strengths increases the free running period. Our present finding may shed new light on the understanding of the heterogeneous SCN network and provides an alternative explanation for the diversity of free running periods between species.
主要的内源性时钟，称为视交叉上核（SCN），调节哺乳动物行为和生理活动的昼夜节律。SCN 的一个主要特征是，在没有每日光-暗循环的情况下（称为自由运行周期），动物维持接近 24 小时的昼夜节律。由于 SCN 网络的异质性，自由运行周期在不同物种之间有所不同。先前的研究表明，细胞耦合以及内在神经元周期的异质性缩短了自由运行周期。此外，根据实验得出，一个神经元的耦合强度与其周期呈负相关。目前尚不清楚这种耦合强度与周期之间的关联对自由运行周期有什么影响，以及耦合强度的异质性如何影响这个自由运行周期。在本研究中，我们发现，在一个神经元的耦合强度与其周期之间存在负相关关系的情况下，令人惊讶的是，耦合强度的分散性增加了自由运行周期。我们目前的发现可能为理解异质 SCN 网络提供新的视角，并为物种间自由运行周期的多样性提供另一种解释。
