NEURAL BASIS OF CIRCADIAN ORGANIZATION

在理解生理学方面已经有了实质性的进展， 昼夜节律的基础。 这些进步，在很大程度上， 部分，通过使用无脊椎动物模型， 脊椎动物昼夜节律系统的形式属性，但它允许 细胞水平的分析。 海洋软体动物，布拉，被证明是一个首演准备， 解决关于昼夜节律系统的两个基本问题：1） 控制昼夜节律的夹带和产生的细胞机制 节律性，以及2）昼夜节律起搏器相互作用的机制 （昼夜节律组织）。 我们以前的工作已经证明，Bulla眼表达了昼夜节律， 视神经脉冲频率的节律，由神经元产生， 视网膜的底部 这些神经元表现出昼夜节律， 膜电位可以通过处理发生相移， 使膜脱附。 此外，两个人体内的昼夜节律起搏器 眼睛通过传出视神经纤维彼此耦合。 这 互耦改变了耦合系统的自由运行周期， 可以在体外进行研究。 我们打算继续我们的研究泡视网膜，并有两个主要的 目的：1）探讨跨膜电位和离子通道在细胞膜上的作用 传导的夹带和产生的昼夜节律内 视网膜神经元，和2）我们希望定量分析的途径， 它们将大疱和囊状体中的眼部昼夜节律起搏器连接起来， 另一条后鳃上有眼起搏器 我们准备开发 一个由神经冲动诱导昼夜节律起搏器的模型。 这样的 框架具有实用性，了解夹带的过程中， 哺乳动物的昼夜节律系统，其中下丘脑起搏器通过 眼睛的神经输入

There has been substantial progress towards understanding the physiological basis of circadian rhythmicity. These advances have been made, in large part, through the use of invertebrate models, preparations which display the formal properties of vertebrate circadian systems, but which allow for a cellular level of analysis. The marine mollusc, Bulla, is proving to be a premiere preparation for addressing two fundamental questions about circadian systems: 1) the cellular mechanisms governing the entrainment and generation of circadian rhythmicity, and 2) the mechanisms by which circadian pacemakers interact (circadian organization). Our previous work has demonstrated that the Bulla eye expresses a circadian rhythm in optic nerve impulse frequency which is generated by neurons at the base of the retina. These neurons exhibit a circadian rhythm in membrane potential which can be phase shifted by treatments which depolarize the membrane. In addition, the circadian pacemakers in the two eyes are coupled to one another via efferent optic nerve fibers. This mutual coupling alters the free-running period of the coupled system and can be studied in vitro. We intend to continue our study of the Bulla retina and have two major goals: 1) we wish to explore the role of transmembrane potential and ionic conductances in the entrainment and generation of circadian rhythms within retinal neurons, and 2) we wish to quantitatively analyze the pathways which couple the ocular circadian pacemakers in both Bulla and Bursatella, another opisthobranch with coupled ocular pacemakers. We intend to develop a model for entrainment of circadian pacemakers by neural impulses. Such a framework has utility for understanding the process of entrainment in mammalian circadian systems where a hypothalamic pacemaker is entrained via neural input from the eyes.