Gu Changgui, Xu Jinshan, Liu Zonghua, Rohling Jos H T
Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, 2300 RC, The Netherlands.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Aug;88(2):022702. doi: 10.1103/PhysRevE.88.022702. Epub 2013 Aug 2.
The suprachiasmatic nucleus (SCN) is a principal circadian clock in mammals, which controls physiological and behavioral daily rhythms. The SCN has two main features: Maintaining a rhythmic cycle of approximately 24 h in the absence of a light-dark cycle (free-running period) and the ability to entrain to external light-dark cycles. Both free-running period and range of entrainment vary from one species to another. To understand this phenomenon, we investigated the diversity of a free-running period by the distribution of coupling strengths in our previous work [Phys. Rev. E 80, 030904(R) (2009)]. In this paper we numerically found that the dispersion of intrinsic periods among SCN neurons influence the entrainment range of the SCN, but has little influence on the free-running periods under constant darkness. This indicates that the dispersion of coupling strengths determines the diversity in free-running periods, while the dispersion of intrinsic periods determines the diversity in the entrainment range. A theoretical analysis based on two coupled neurons is presented to explain the results of numerical simulations.
视交叉上核（SCN）是哺乳动物的主要昼夜节律时钟，它控制着生理和行为的日常节律。SCN有两个主要特征：在没有明暗周期的情况下维持大约24小时的节律周期（自由运行周期）以及能够与外部明暗周期同步。自由运行周期和同步范围因物种而异。为了理解这一现象，我们在之前的工作[《物理评论E》80, 030904(R) (2009)]中通过耦合强度的分布研究了自由运行周期的多样性。在本文中，我们通过数值计算发现，SCN神经元内在周期的离散度会影响SCN的同步范围，但在持续黑暗条件下对自由运行周期影响很小。这表明耦合强度的离散度决定了自由运行周期的多样性，而内在周期的离散度决定了同步范围的多样性。本文基于两个耦合神经元进行了理论分析来解释数值模拟结果。
