The Human Foveal Connectome

视锥光感受器细胞与视网膜回路、Müller胶质细胞和视网膜色素的复杂关系 视网膜上皮细胞（RPE）对正常视力至关重要。然而，对于中央凹中心的锥体来说， 峰值视敏度这些关系的特征很差。长期以来， 对细胞和亚细胞中心凹结构的理解是多种多样的 嵌入并微型化在复杂三维结构中的细胞类型。广泛的长期 这项新的研究计划的目的是通过应用新的 体积电子显微镜（Connectomics）。我们将利用视网膜组织从一个 创新的器官捐赠计划，将允许恢复前光学相干断层扫描（OCT）成像， 评估视网膜健康状况和中央凹凹形态，并指导连接重建。初步 来自两个供体眼睛的数据证明了完全重建中央凹锥体及其 相关的突触通路、米勒细胞和RPE细胞。第一次重建锥微电路从 一个成年早产儿表明，中央凹视觉的关键细胞和突触通路在 结构和定位预期从以前的工作对非人灵长类动物。因此，在目标1中， 建议定位，识别和定量重建突触视觉通路， 最中央的中央凹锥体我们将描述所有的双极和神经节细胞回路， 这些锥体和测试新的假设，占主导地位的“侏儒”途径subserving空间敏锐度可能是 个体之间在电路和小窝定位方面差异很大。我们将进一步检验假设， 在侏儒电路之外，中央凹中心产生了20多个不同的但尚未特征化的视觉信号。 途径。Müller细胞的第一次重建揭示了锥体轴突的紧密包裹， 丛状层和中心凹底有丰富的突起。在目标2中，我们建议完成 Müller细胞的重建，以检验中心凹底包含一种新的Müller细胞类型的假设 仅限于内层视网膜，单个Müller细胞的形态及其中央凹分布解释了 黄斑色素分布。视网膜色素上皮细胞的首次重建为视网膜色素上皮细胞的功能提供了新的见解。 在临床OCT和自体荧光成像中重要的细胞器分布。因此，在目标3中，我们 建议重建和计数的RPE细胞中的细胞器在锥只有凹和混合 杆锥中央凹我们将直接检验RPE细胞器含量和分布不同的假设， 在仅视锥中心凹和视杆细胞丰富的中央凹周围之间，解释了OCT带的出现， 临床成像中自体荧光信号的拓扑学。该提案结合了专业知识和创新， 神经生物学、病理学、成像学和连接组学。结果将影响视网膜神经生物学、临床影像学 解释和黄斑疾病，特别是年龄相关性黄斑变性的病理生理学。

The complex relationship of cone photoreceptor cells with retinal circuits, Müller glia, and retinal pigment epithelial (RPE) cells is essential to normal vision. Yet for the cones in the very center of the fovea that mediate peak visual acuity these relationships are poorly characterized. A longstanding barrier to a comprehensive understanding of cellular and subcellular foveal structure is the myriad interactions among a great diversity of cell types embedded and miniaturized within a complex three-dimensional architecture. The broad long-term objective of this new research program is to elucidate foveal microstructure directly by application of new methods of volume electron microscopy (connectomics). We will utilize retinal tissue acquired from an innovative organ donor program that will permit pre-recovery optical coherence tomography (OCT) imaging to assess retinal health status and foveal pit morphology and to guide connectomic reconstruction. Preliminary data from two donor eyes demonstrates feasibility of complete reconstructions of foveal cones and their associated synaptic pathways, Müller cells, and RPE cells. The first reconstructions of cone microcircuits from an adult born preterm indicate that the critical cells and synaptic pathways for foveal vision differ dramatically in structure and localization anticipated from previous work on non-human primates. Therefore in Aim 1 we propose to localize, identify and reconstruct quantitatively the synaptic visual pathways that arise from the central-most foveal cones. We will characterize all of the bipolar and ganglion cell circuits arising from these cones and test the new hypothesis that the dominant “midget” pathway subserving spatial acuity may be highly variable across individuals in both circuitry and pit localization. We will further test the hypothesis that beyond the midget circuit the foveal center gives rise to over twenty distinct but as yet uncharacterized visual pathways. The first reconstructions of Müller cells revealed the intimate wrapping of cone axons and abundance of processes in the plexiform layer and foveal floor. In Aim 2 we propose complete reconstructions of Müller cells to test the hypotheses that the foveal floor contains a novel Müller cell type restricted to inner retina and that morphology of individual Müller cells and their foveal distribution accounts for the macular pigment distribution. The first reconstructions of RPE cells provided new insights on the distribution of organelles important in clinical OCT and autofluorescence imaging. Therefore, in Aim 3 we propose to reconstruct and enumerate organelles in RPE cells in the cone-only fovea and the mixed rod-cone perifovea. We will directly test the hypothesis that RPE organelle content and distribution differs between cone-only fovea and rod-rich perifovea, accounting for the appearance of OCT bands and for topography of autofluorescence signal in clinical imaging. This proposal combines expertise and innovation in neurobiology, pathology, imaging, and connectomics. Outcomes will impact retinal neurobiology, clinical image interpretation, and pathophysiology of macular diseases, especially age-related macular degeneration.