NEURONAL PLASTICITY IN THE RETINA

本研究项目是一项实验性研究，旨在了解 神经网络如何改变或适应环境的变化 刺激.在鱼类视网膜中， 水平细胞，一种接受突触的二级细胞， 视锥细胞的接触，取决于环境照明和昼夜节律 时钟生物钟是一种生物振荡器， 持续的节律性，大约持续24小时， 缺乏外部定时提示（例如持续黑暗）。另外还有按 生物钟可以被周期性的环境刺激所携带，例如 光暗适应后，红视锥细胞向视锥水平细胞输入 在白天占主导地位，杆输入占主导地位， 晚上。因为这些影响是在饲养的鱼类中观察到的， 持续的黑暗，因为光/暗循环的先前逆转 相反的影响，可以得出结论，生物钟调节 黑暗适应的影响。然而，昼夜因素， 调节暗适应对视锥水平细胞的影响， 已知的，也不是因素，夹带时钟以下逆转 光明/黑暗的循环 因此，电生理学、神经化学和 解剖技术将被用来研究昼夜节律 调节金鱼视网膜的暗适应效应。它 将确定生物钟是否调节锥体水平 细胞耦合，以及是否有昼夜节律， 视网膜神经递质、多巴胺和褪黑激素的水平，和/或 还将确定昼夜节律是否 在水平细胞中，光反应取决于多巴胺的节律， 褪黑激素，以及对细胞外pH值的节奏。最后，它将是 确定多巴胺是否参与了生物钟的夹带。的 膜电位、光诱发反应、电偶联和染料偶联 将在恒定条件下研究锥体水平细胞的数量 黑暗中，使用灌流，完整的视网膜准备。 视网膜生物钟过程的破坏可能介导 感光细胞变性因此，增加了对 生物钟过程和途径以及发射器功能将 有助于了解人类视网膜过程和功能障碍， 并为视网膜疾病的药物治疗提供基础。在 此外，增加对多巴胺在视网膜中作用的了解， 帮助了解和治疗帕金森病。

This research project is an experimental study that seeks to understand how neuronal networks change or adapt to changes in environmental stimulation. In the fish retina, the light-evoked responses of cone horizontal cells, a type of second order cell that receives synaptic contact from cones, depend on the ambient illumination and on a circadian clock. A circadian clock is a type of biological oscillator that has persistent rhythmicity with a period of approximately 24 hours in the absence of external timing cues (e.g. constant darkness). In addition, a circadian clock can be entrained by cyclic environmental stimuli, such as light. Following dark adaptation, red cone input to cone horizontal cells predominates during the daytime and rod input predominates during the nighttime. Because these effects are observed in fish maintained in constant darkness and because prior reversal of the light/dark cycle reverses the effects, it can be concluded that a circadian clock regulates the effects of dark adaptation. However, the circadian factors that regulate the effects of dark adaptation on cone horizontal cells are not known, nor are the factors that entrain the clock following reversal of the light/dark cycle. Accordingly, a combination of electrophysiological, neurochemical and anatomical techniques will be used to investigate circadian rhythmic regulation of the effects of dark adaptation in the goldfish retina. It will be determined whether a circadian clock regulates cone horizontal cell coupling, as well as whether there are circadian rhythms in the levels of the retinal neurotransmitters, dopamine and melatonin, and/or in extracellular pH. It will also be determined whether the circadian rhythm in horizontal cell light responses depends on rhythms of dopamine and melatonin, as well as on a rhythm of extracellular pH. Finally, it will be determined whether dopamine is involved in entrainment of the clock. The membrane potential, light-evoked responses and electrical and dye coupling of cone horizontal cells will be studied under conditions of constant darkness, using a superfused, intact retina preparation. Disruption of circadian clock processes in the retina may mediate photoreceptor cell degeneration. Thus, increased understanding of circadian clock processes and pathways and of transmitter function will aid in the understanding of human retinal processes and dysfunction, as well as provide the basis for drug therapy for retinal disorders. In addition, increased knowledge of the action of dopamine in the retina may aid in the understanding and treatment of Parkinson's disease.