Optical Measurements of Excitatory Synaptic Function in Retinal Circuitry

视网膜回路兴奋性突触功能的光学测量

• 批准号: 8425741
• 负责人: Bart Gerard Borghuis
• 金额: $ 20.78万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-12-01 至 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8425741
• 关键词: AMPA Receptors; Affinity; Aging; Amacrine Cells; Binding; Cells; Complement; Custom; Dendrites; Disease; Distal; Event; Eye; Fluorescence; Glaucoma; Glutamates; Goals; Heterogeneity; Image; Imaging technology; In Vitro; Individual; Ischemia; Knowledge; Label; Life; Light; Location; Measurement; Measures; Mental Depression; Methods; Microscope; Microscopy; Modeling; Monitor; Neurons; Noise; Optic Nerve; Optics; Output; Pathway interactions; Photoreceptors; Physiological; Population; Presynaptic Terminals; Process; Property; Reporter; Retina; Retinal; Retinal Cone; Retinal Diseases; Retinitis Pigmentosa; Role; Signal Transduction; Site; Stimulus; Synapses; Synaptic Transmission; System; Testing; Time; Tissues; Tomatoes; Trees; Variant; Vertebrate Photoreceptors; Vesicle; Virus; Vision; Visual; Whole-Cell Recordings; Work; age effect; base; cell type; design; ganglion cell; genetic technology; insight; light intensity; neurotransmitter release; normal aging; novel strategies; parallel processing; patch clamp; postsynaptic; prevent; promoter; public health relevance; receptive field; receptor; research study; response; retinal neuron; sensor; synaptic depression; synaptic function; two-photon; uptake; visual adaptation; visual information

DESCRIPTION (provided by applicant): Our long-term goal is to understand how visual information is processed by the retina at the level of specific cell types and synapses. Retinal processing depends critically on a vertical, excitatory glutamatergic pathway, from photoreceptors  bipolar cells  ganglion cells (output neurons). Bipolar cell synapses have been proposed to express multiple important functions, including: the ability to release at high rates to maintain a high signal-to-noise ratio; the ability to release either synaptically or extrasynaptically and thereby signal different receptor populations; the ability to generate visual adaptation through use-dependent plasticity; and the ability to generate receptive field properties, including direction selectivity. All proposed functions have been difficult to study wih the common method of whole-cell patch clamp recording: patch recording cannot resolve individual synaptic inputs within the dendritic tree and cannot accurately measure large conductances or small signals on distal dendrites. Here, we propose a new combination of methods that will yield fundamental insights into bipolar cell synaptic transmission. We will use a newly-developed genetically encoded glutamate sensor (iGluSnFR), delivered with a virus injected into the vitreous of the eye and expressed under the control of promoters that drive expression in identified postsynaptic targets of bipolar cells. When iGluSnFR binds glutamate, its fluorescent properties change and these changes can be measured with two-photon microscopy. We have a working two-photon microscope system that is optimized for fluorescence measurements during cone photoreceptor stimulation in vitro. Aim 1 will characterize glutamate release onto amacrine and ganglion cells down to the level of individual synapses and vesicles. We will correlate iGluSnFR signals with spontaneous and light-evoked electrical events, in time, and with synaptic locations, in space. Glutamate spillover will be imaged under conditions with either elevated release or limited glutamate uptake. Aim 2 will image synaptic depression at individual synapses and test its role in contrast adaptation. Aim 3 will test for parallel processing at the output of single bipolar terminals by measuring directiona selectivity of glutamate release at individual synapses onto direction-selective ganglion cells. These studies will yield fundamental insights into the functional organization of the retina at the level of synapses and will be applicable to study the effects of aging and disease on retinal function.

描述（由申请人提供）：我们的长期目标是了解视网膜在特定细胞类型和突触水平上如何处理视觉信息。视网膜加工主要依赖于光感受器双极细胞神经节细胞（输出神经元）的垂直兴奋性谷氨酸能通路。双极细胞突触被认为具有多种重要功能，包括：高速率释放以维持高信噪比的能力；在突触或突触外释放的能力，从而向不同的受体群体发出信号；产生视觉效果的能力