Glycine subunit specific inhibition and ganglion cell visual responses

视网膜神经节细胞(GC)整合兴奋性和抑制性输入，并执行编码 视觉场景的多样特征。这些功能和形态不同GC的输出建立了 视觉信号流，在整个视觉通路中保持。归根结底，它们创造了我们对 物体的大小、形状和颜色以及它们在空间中的关系。它们在时间上建立了对象之间的关系，因此 我们知道它什么时候静止或运动，什么时候运动，它的方向和速度。为此，有一个 视网膜抑制性神经递质系统之间的一般分工。GABA及其受体， 调节空间视觉，而甘氨酸及其受体调节时间视觉。有五种甘氨酸 受体亚基(1个β和4个αS)。GlyRα亚基与单个β亚基结合使其具有功能 具有不同生物物理性质的受体。我们的工作表明，所有GC都表达一个或多个GlyRα‘S和 不同GC类型的组成有所不同。我们假设多样性增强了抑制功能的多样性。 并且在GC类型内，并且被用来编码视觉场景。然而，GlyRα亚基的特殊功能是 几乎完全未知。 我们知道，突触前GABA和甘氨酸能无长突细胞的反应(和递质释放) GCs受其他甘氨酸能无长突细胞输入的调节。这意味着，在GlyRs能够选择性地 在GC或ACEs中消除，我们不能消除直接GlyRα抑制GCs从GlyRα调制中的作用 在向GC提供输入的上游电路中。我们开发了一种新型的AAV-shRNA敲除(KD) 一种方法，消除单个G-lyrα亚基在GC中的表达，而保留其上游表达 完好无损。我们建议使用这种方法来定义GlyRα直接抑制在7种已确定的GC类型中的作用，并通过 扩大孤立的GABA输入在这些相同GC中的作用。在目标1中，我们询问由4个功能不同的αGC表达的单个GlyRα，GlyRα1是否调节其视觉反应的相同或不同方面。在《目标2》中，我们问 两个不同的GlyRα亚基在同一GC中表达，增加了抑制的多样性，以调制不同的 单一GC类型中的视觉响应的各个方面。我们使用电生理测试来表征尖峰 GC的反应、基础电流及兴奋性和抑制性动力学之间的关系 与突触后反应一起输入。 这项提议解决了新的概念：不同的甘氨酸亚基特异性抑制与 控制视觉计算的突触前输入。

Retinal ganglion cells (GCs) integrate excitatory and inhibitory inputs and perform computations that encode diverse features of the visual scene. The output of these functionally and morphologically diverse GCs establish visual signaling streams, maintained throughout the visual pathway. Ultimately, they create our perception of the size, shape and color of objects and their relationships in space. They establish relationships of objects in time, so that we know when it is stationary or moving, and when moving, its direction and velocity. To this end, there is a general division of labor between the retina's inhibitory neurotransmitter systems. GABA, and its receptors, modulate spatial vision, whereas glycine, and its receptors, modulate temporal vision. There are five glycine receptor subunits (one β and 4αs). The GlyRα subunits combine with a single β subunit to make functional receptors with diverse biophysical properties. Our work shows that all GCs expresses one or more GlyRα’s and the composition differs across GC type. We hypothesize that variety enhances the diversity of inhibitory functions across and within GC types and are used to encode the visual scene. However, the specific function of GlyRα subunits is almost completely unknown. We know that the responses (and transmitter release) of the GABA and glycinergic amacrine cells presynaptic to GCs are modulated by other glycinergic amacrine cell input. This means that until GlyRs can be selectively eliminated in GCs or ACs, we cannot disambiguate the role of direct GlyRα inhibition to GCs from GlyRα modulation in the upstream circuit that provides input to the GCs. We developed a novel AAV-shRNA knockdown (KD) approach that eliminates expression of individual G lyRα subunits in GCs, while leaving their upstream expression intact. We propose to use this approach to define the role of GlyRα direct inhibition in 7 identified GC types and by extension the role of isolated GABA inputs in those same GCs. In Aim 1 we ask if a single GlyRα, GlyRα1 expressed by the 4 functionally diverse αGCs modulates the same or different aspects of their visual responses. In aim 2 we ask if two different GlyRα subunits, expressed in the same GC, increase the diversity of inhibition to modulate different aspects of the visual response in a single GC type. We use electrophysiological assays to characterize the spiking responses of the GCs, underlying currents and the relationships between the kinetics of excitatory and inhibitory input with the postsynaptic response. This proposal addresses the novel concept: that diverse glycine subunit specific inhibition interacts with presynaptic inputs to controls visual computation.