Neurobiology of Circadian Rhythms

哺乳动物下丘脑的视交叉上核是生理时钟的解剖学基础，它控制着生理和行为中的许多明显节律。由视交叉上核产生昼夜节律的机制尚不清楚。然而，我们知道，产生动作电位的能力对于生物钟的运作并不是必需的。因此，其他形式的细胞间通讯必须介导昼夜节律的产生。努涅斯博士将研究神经元与视交叉上核胶质细胞之间的相互作用是否至关重要。利用电子显微镜，他将确定神经胶质细胞形态在昼夜周期中的可塑性是否会影响神经元间的通讯，从而对视交叉上核的神经输出施加昼夜节律性。作为当代生物学的组织原则，生物计时的概念与体内平衡的概念相竞争。了解基本的神经机制可能会带来治疗方法，帮助解决由时差、轮班工作和老年人睡眠障碍引起的问题。事实上，只要昼夜节律研究最终将影响到人类在各个季节和一天中的各个阶段所从事的几乎所有领域，这项工作可能会对国家的科学和工程研究、教育和人力资源基础产生直接影响。

The mammalian suprachiasmatic nucleus of the hypothalamus is the anatomical substrate for a circadian biological clock that controls many overt rhythms in physiology and behavior. The mechanism(s) responsible for the generation of circadian rhythmicity by the suprachiasmatic nucleus is (are) unknown. It is known, however, that the ability to generate action potentials is not necessary for the workings of the circadian clock. Therefore, other forms of intercellular communications must mediate circadian-rhythm generation. Dr. Nunez will examine the possibility that the interaction between neurons and glial cells of the suprachiasmatic nucleus is critical. Using electronmicroscopy, he will determine whether plasticity in glial cell morphology over the circadian cycle impacts on inter-neuronal communications and, thus, impose circadian rhythmicity on the neural outputs of the suprachiasmatic nucleus. The concept of biological timing rivals that of homeostasis as an organizing principle in contemporary biology. Understanding the basic neural mechanisms may lead to treatments that could help solve problems caused by jet lag, shift work and sleep disorders in the elderly. Indeed, in so far as circadian rhythm studies will ultimately have an impact on virtually all areas of human endeavor distributed across the seasons and phases of the day, this work may have a direct effect on the nation's scientific and engineering research, education and human resources bases.