ACTIVITY-DEPENDENT MATURATION OF INNER RETINAL CIRCUITRY

活动对中枢神经系统(CNS)许多区域的正常发育起着重要的引导作用，视网膜也不例外。在年轻时干扰正常的感觉输入会对神经组织的发育产生深远的影响，并可能导致永久性的功能缺陷。在黑暗中饲养啮齿动物(“黑暗饲养”)会改变视网膜输出神经元--视网膜神经节细胞(RGC)的反应。为了确定活动如何引导中枢神经系统回路的成熟，这项提议的具体目的是试图确定视网膜回路的变化导致这些已知的视网膜输出的变化，这些变化是由于发育过程中光剥夺造成的。视网膜节细胞接受来自双极细胞的输入，双极细胞对光感受器的活动做出反应，释放谷氨酸。抑制性无长突细胞对于适当地控制这种双极传入视网膜节细胞很重要。利用全细胞膜片钳技术，通过记录自发事件和通过激发双极终末和无长突树突之间的相互突触的反应，将在正常饲养和黑暗饲养的动物的视网膜中检查无长突细胞输入到双极细胞的发育。来自不同培养条件的双极细胞释放谷氨酸的能力也将通过记录视网膜神经节细胞的诱发反应和通过测量钙进入分离的双极细胞终末，使用钙指示剂染料和培养中急性分离的双极细胞的荧光成像来研究。目的是确定这些双极细胞的输入和/或双极细胞谷氨酸释放特性是否在发育早期被活动剥夺所改变。这些属性严重影响RGC的输出。

Activity plays an important role in guiding the normal development of many areas in the central nervous system (CNS), and the retina is no exception. Interfering with normal sensory input at young ages has profound effects on the development of nervous tissue and can lead to permanent deficits in function. Raising rodents in the dark ("dark rearing") alters responses recorded in the output neurons of the retina, the retinal ganglion cells (RGCs). In order to identify how activity can guide maturation of CNS circuitry, the specific aims of this proposal seek to determine the alterations in retinal circuitry leading to these known changes in retinal output resulting from light-deprivation during development. The RGCs receive their input from bipolar cells, which release glutamate in response to photoreceptor activity. Inhibitory amacrine cells are important for proper control of this bipolar input to RGCs. Using whole- cell patch clamp techniques, the development of amacrine cell inputs to bipolar cells will be examined in the retinas of both normally reared and dark reared animals by recording spontaneous events and by evoking responses from reciprocal synapses made between bipolar terminals and amacrine dendrites. The ability of bipolar cells from different rearing conditions to release glutamate will also be studied by recording evoked responses in RGCs and by measuring calcium entry into isolated bipolar cell terminals, using calcium indicator dyes and fluorescent imaging of acutely isolated bipolar cells in culture. The goal is to determine whether these bipolar cell inputs and/or bipolar cell glutamate release properties are altered by activity deprivation during early development. These properties critically affect RGC output.