Neurobehavioral Differences in Circadian Rhythms

昼夜节律是每天在同一时间重复的周期性生物活动。 在哺乳动物中，大脑中一个叫做视交叉上核（SCN）的部分对这些节奏非常重要，并且构成了生物钟机制的一部分。 这些节奏在恒定的条件下继续运行，但环境线索，如日光的时间可以设置，或夹带，周期的时间或相移。 性别差异已被描述在夹带的昼夜节律的大多数哺乳动物已被检查，最近的数据表明，类固醇激素可以影响的生理时钟的功能，在SCN的生物化学。 大多数用于昼夜节律研究的动物都是夜间活动的啮齿动物，但也有一些关于两种白天活动的物种的数据，人类和一种称为德古的啮齿动物。 在德古，性二态性昼夜节律的影响被认为是对自由运行的时期，光刺激，和激素的调制，以及其他因素。 性二态性在青春期后发展，似乎需要两性的变化。 该项目使用生物化学，分子和行为方法来确定当SCN中雌激素和/或雄激素的分子受体上调时是否发生性分化，以及昼夜节律的性分化是否反映在产生周期的关键细胞蛋白（PER和CRY）的基因表达的变化周期中。 该项目的结果对于普通生物学和心理学以及神经内分泌学，理解哺乳动物昼夜节律的激素和遗传机制，与夜间哺乳动物的进化比较以及更好地理解人类昼夜节律在青春期的发展具有重要意义。 这个项目也是在一个实验室，具有良好的研究指导记录。

Circadian rhythms are cyclic biological activities that recur at the same time every day. In mammals, a part of the brain called the suprachiasmatic nucleus (SCN) is important for these rhythms, and constitutes part of the biological clock mechanism. These rhythms continue to run under constant conditions, but environmental cues such as timing of daylight can set, or entrain, the timing or phase-shifting of the cycles. Sex differences have been described in the entrained circadian rhythms of most mammals that have been examined, and recent data suggest that steroid hormones can influence the function of the circadian clock biochemistry in the SCN. Most animals used for circadian research are nocturnal rodents, but there are some data on two diurnal species, the human and a rodent called the degu. In the degu, sexually dimorphic circadian effects are seen in responses to free-running periods, light stimuli, and modulation by hormones, among other factors. The sexual dimorphism develops just after puberty, and appears to require changes in both sexes. This project uses biochemical, molecular and behavioral approaches to determine whether sexual differentiation occurs when molecular receptors for estrogen and/or androgen are up-regulated in the SCN, and whether sexual differentiation of circadian rhythms is reflected in changed cycles of the gene expression of key cellular proteins (PER and CRY) that generate the cycles. Results from this project will be important for general biology and psychology as well as neuroendocrinology, for understanding hormonal and genetic mechanisms of circadian rhythms in mammals, for evolutionary comparisons with nocturnal mammals, and potentially for better understanding of how human circadian rhythms develop during adolescence. This project is also in a laboratory with an excellent record of research mentoring.