ACTIVITY-DEPENDENT MATURATION OF INNER RETINAL CIRCUITRY

活动在引导中枢神经系统（CNS）许多区域的正常发育中起着重要作用，视网膜也不例外。在年轻时干扰正常的感觉输入对神经组织的发育有深远的影响，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，即视网膜神经节细胞（RGCs）的反应记录。为了确定活动如何引导中枢神经系统回路的成熟，本提案的具体目标是确定视网膜回路的改变，导致这些已知的视网膜输出变化，这些变化是由发育过程中的光剥夺引起的。rgc接收来自双极细胞的输入，双极细胞释放谷氨酸以响应光感受器的活动。抑制性无分泌细胞对于适当控制这种双极输入的RGCs是重要的。利用全细胞膜片钳技术，在正常饲养和暗饲养的动物视网膜中，通过记录自发事件和唤起双极终端和无突树突之间形成的互反突触的反应，研究无突细胞输入双极细胞的发展。不同饲养条件下的双极细胞释放谷氨酸的能力也将通过记录rgc的诱发反应和测量钙进入分离的双极细胞末端，使用钙指示染料和培养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改变。这些属性严重影响了RGC的产出。

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.