Correlation with Behavioral Activity and Rest Implies Circadian Regulation by SCN Neuronal Activity Levels
Correlation with Behavioral Activity and Rest Implies Circadian Regulation by SCN Neuronal Activity Levels
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DOI：
10.1177/0748730409349895
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发表时间：
2009-12-01
影响因子：
3.5
通讯作者：
Meijer, Johanna H.
中科院分区：
文献类型：
--
作者：
Houben, Thijs;Deboer, Tom;Meijer, Johanna H.
下丘脑的SCN包含一个主要的起搏点，其电脉冲频率呈现24小时节律。虽然已知SCN电活动在白天高而在夜间低，但电活动与行为节律之间的精确关系几乎完全未知。作者在自由活动小鼠中，借助植入的微电极与饮水活动平行地进行了SCN多单位活动的长期记录。实验动物分别处于12 h：12 h光暗周期（LD 12：12）、短日照（LD 8：16）和长日照（LD 16：8）。行为活动的发作和偏移发生在SCN放电约为半最大值时。80%的发作和62%的偏移发生在SCN电活动与半最大电活动水平相差小于15%时。休息和活动之间的转换可以用S形概率曲线来描述，希尔系数为7.0的起始和5.7的偏移。起始和偏移水平的相似性表明SCN对行为活动的控制不存在滞后。暴露于短日照或长日照引起的电活动的波形显着改变，但不影响SCN电活动水平的行为转变发生。在所有的光周期，SCN信号是歪斜的，更快速的放电变化在发病期间（每小时19%）比偏移（每小时11%）。昼夜节律系统的精度似乎是优化的，因为行为活动和休息之间的转换发生在SCN电活动的变化最大时，无论是在下降阶段还是上升阶段。作者得出结论，行为状态的转变可以通过半最大电活动水平附近的概率函数来描述，并且SCN的参数（预测行为的开始和偏移）对环境条件非常不敏感。
The SCN of the hypothalamus contains a major pacemaker, which exhibits 24-h rhythms in electrical impulse frequency. Although it is known that SCN electrical activity is high during the day and low during the night, the precise relationship between electrical activity and behavioral rhythms is almost entirely unknown. The authors performed long-term recordings of SCN multiple unit activity with the aid of implanted microelectrodes in parallel with the drinking activity in freely moving mice. The animals were kept in a 12h:12h light-dark cycle (LD 12:12) and in short-day (LD 8:16) and long-day photoperiods (LD 16:8). Onsets and offsets of behavioral activity occurred when SCN discharge was around half-maximum value. Of the onsets 80%, and of the offsets 62%, occurred when SCN electrical activity differed less than 15%, from the half-maximum electrical activity levels. Transitions between rest and activity could be described by a sigmoid shaped probability curve with Hill coefficients of 7.0 for onsets and 5.7 for offsets. The similarity in the onset and offset levels shows an absence of hysteresis in the control of behavioral activity by the SCN. Exposure to short- or long-day photoperiods induced significant alterations ill the waveform of electrical activity but did not affect SCN electrical activity levels at which behavioral transitions occurred. In all photoperiods, the SCN signal was skewed with more rapid discharge changes during onsets (19% per hour) than offsets (11% per hour). The precision of the circadian system appears optimized, as transitions between behavioral activity and rest occur when the change in SCN electrical activity is maximal, both during the declining and rising phase. The authors conclude that transitions in behavioral state can be described by a probability function around half-maximum electrical activity levels and that the parameters of the SCN, predicting onset and offset of behavior, are remarkably insensitive to environmental conditions.