Synaptic Function and Organization of the Mammalian Retina

描述（由申请人提供）：本提案的目标是了解成熟哺乳动物视网膜中复杂视觉处理的突触机制和神经元回路，重点关注方向选择回路中单个突触的功能和组织。这项研究是基于最近的发现，确定关键的突触相互作用的产生的方向选择性。这些发现表明，在潜在的神经元回路中，突触的复杂性达到了以前未被认识的水平。他们揭示了在微电路水平上理解定向计算机制的重要性和可能性。为了直接了解方向选择性微电路的功能和组织，本文提出了一种新的实验方法，该方法集成了双光子成像、双膜片钳记录、点紫外光释放和转基因技术，从而可以在完整的视网膜网络中测量单个突触位点处的神经元连接和相互作用，并将其与视网膜的形态和功能特性相关联。细胞在同一实验中。拟进行的实验旨在了解（1）成熟视网膜中胆碱能传递的突触机制，（2）星爆状无长突细胞和方向选择性神经节细胞之间单个胆碱能和GABA能突触的功能组织，（3）星爆状无长突细胞之间GABA能突触的功能组织，以及（4）双极细胞轴突终末的突触相互作用。从这些实验的结果预计将提供新的见解树突和轴突计算的性质在突触水平和在一个完整的视网膜电路。这种方法也可能为研究其他中枢神经系统回路中单个突触的功能和连通性提供一种新的实验范式。 公共卫生相关性：拟议的研究与公共卫生有关，因为这些研究的结果有望为人类视网膜的功能和烟碱神经传递机制提供新的见解，这对广泛的神经功能和疾病非常重要。

DESCRIPTION (provided by applicant): The goal of this proposal is to understand the synaptic mechanism and neuronal circuitry underlying complex visual processing in the mature mammalian retina, with a focus on the function and organization of individual synapses in the direction selective circuit. The proposed study is based on recent findings that identified critica synaptic interactions underlying the generation of direction selectivity. These findings suggested a previously unappreciated level of synaptic intricacy in the underlying neuronal circuit. They revealed the importance, as well as the possibility, to understand the mechanism of directional computation at a microcircuit level. In order to gain direct knowledge of the function and organization of the direction-selective microcircuits, a novel experimental approach is proposed here, which integrates two-photon imaging, dual patch-clamp recording, spot UV uncaging, and transgenic technology, so that neuronal connectivity and interactions at individual synaptic sites can be measured in an intact retinal network and correlated with the morphological and functional properties of the cells in the same experiment. The proposed experiments are designed to understand (1) the synaptic mechanism of cholinergic transmission in the mature retina, (2) the functional organization of individual cholinergic and GABAergic synapses between starburst amacrine and direction-selective ganglion cells, (3) the functional organization of GABAergic synapses between starburst amacrine cells, and (4) the synaptic interactions at bipolar cell axon terminals. Results from these experiments are expected to provide novel insights into the nature of dendritic and axonal computation at a synaptic level and in an intact retinal circuit. This approach may also provide a novel experimental paradigm for studying the function and connectivity at individual synapses in other CNS circuits. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health, because the results of the studies are expected to provide novel insights into the function of the human retina and the mechanism of nicotinic neurotransmission, which is important for a wide range of neural functions and diseases.