Data from: Neural correlates of individual differences in circadian behavior

Daily rhythms in mammals are controlled by the circadian system, which is a collection of biological clocks regulated by a central pacemaker within the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. Changes in SCN function have pronounced consequences for behaviour and physiology; however, few studies have examined whether individual differences in circadian behaviour reflect changes in SCN function. Here, PERIOD2::LUCIFERASE mice were exposed to a behavioural assay to characterize individual differences in baseline entrainment, rate of re-entrainment and free-running rhythms. SCN slices were then collected for ex vivo bioluminescence imaging to gain insight into how the properties of the SCN clock influence individual differences in behavioural rhythms. First, individual differences in the timing of locomotor activity rhythms were positively correlated with the timing of SCN rhythms. Second, slower adjustment during simulated jetlag was associated with a larger degree of phase heterogeneity among SCN neurons. Collectively, these findings highlight the role of the SCN network in determining individual differences in circadian behaviour. Furthermore, these results reveal novel ways that the network organization of the SCN influences plasticity at the behavioural level, and lend insight into potential interventions designed to modulate the rate of resynchronization during transmeridian travel and shift work..

哺乳动物的日常节律由昼夜节律系统调控，该系统由一组生物时钟组成，其运转受下丘脑前部视交叉上核（suprachiasmatic nucleus, SCN）内的中央起搏器所调节。视交叉上核功能的改变会对动物行为与生理机能产生显著影响，但目前鲜有研究探讨昼夜节律行为的个体差异是否反映了视交叉上核的功能变化。本研究以PERIOD2::LUCIFERASE小鼠为实验对象，通过行为学实验表征其基线节律同步、重同步速率及自由运转节律的个体差异。随后我们收集小鼠的视交叉上核脑片进行离体生物发光成像，以解析视交叉上核时钟的特性如何影响行为节律的个体差异。其一，运动活动节律的时间个体差异与视交叉上核节律的时间呈现正相关关系；其二，模拟跨时区飞行条件下的节律调整速率越慢，视交叉上核神经元的相位异质性程度越高。综上，本研究结果证实了视交叉上核网络在决定昼夜节律行为个体差异中的关键作用。此外，本研究揭示了视交叉上核网络组织如何影响行为层面可塑性的全新机制，并为开发潜在干预手段提供了理论依据，这类干预手段旨在调节跨时区旅行与轮班工作期间的节律重同步速率。