There are more than 30 distinct types of mammalian retinal ganglion cells, each sensitive to different features of the visual environment. In rabbit retina, they can be grouped into four classes according to their morphology and stratification of their dendrites in the inner plexiform layer (IPL). The goal of this study was to describe the synaptic inputs to one type of Class IV ganglion cell, the third member of the sparsely branched Class IV cells (SB3). One cell of this type was partially reconstructed in a retinal connectome developed using automated transmission electron microscopy (ATEM). It had slender, relatively straight dendrites that ramify in the sublamina a of the IPL. The dendrites of the SB3 cell were always postsynaptic in the IPL, supporting its identity as a ganglion cell. It received 29% of its input from bipolar cells, a value in the middle of the range for rabbit retinal ganglion cells studied previously. The SB3 cell typically received only one synapse per bipolar cell from multiple types of presumed OFF bipolar cells; reciprocal synapses from amacrine cells at the dyad synapses were infrequent. In a few instances, the bipolar cells presynaptic to the SB3 ganglion cell also provided input to an amacrine cell presynaptic to the ganglion cell. There was apparently no crossover inhibition from narrow-field ON amacrine cells. Most of the amacrine cell inputs were from axons and dendrites of GABAergic amacrine cells, likely providing inhibitory input from outside the classical receptive field.

中文翻译：

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从已识别的双极细胞和无长突细胞到兔视网膜中稀疏分支的神经节细胞的突触输入

哺乳动物视网膜神经节细胞有 30 多种不同类型，每种都对视觉环境的不同特征敏感。在兔视网膜中，根据它们的形态和内部丛状层 (IPL) 中树突的分层，它们可以分为四类。本研究的目的是描述一种 IV 类神经节细胞的突触输入，这是稀疏分支的 IV 类细胞 (SB3) 的第三个成员。这种类型的一个细胞在使用自动透射电子显微镜 (ATEM) 开发的视网膜连接组中部分重建。它有细长、相对直的树突，在 IPL 的下层 a 中分枝。SB3 细胞的树突在 IPL 中总是突触后，支持其作为神经节细胞的身份。它从双极细胞接收了 29% 的输入，先前研究的兔视网膜神经节细胞范围的中间值。SB3 细胞通常从多种假定的 OFF 双极细胞中每个双极细胞仅接收一个突触；来自二元突触的无长突细胞的相互突触并不常见。在少数情况下，SB3 神经节细胞突触前的双极细胞也为神经节细胞突触前的无长突细胞提供输入。窄场无长突细胞显然没有交叉抑制。大多数无长突细胞输入来自 GABAergic 无长突细胞的轴突和树突，可能提供来自经典感受野之外的抑制输入。SB3 细胞通常从多种假定的 OFF 双极细胞中每个双极细胞仅接收一个突触；来自二元突触的无长突细胞的相互突触并不常见。在少数情况下，SB3 神经节细胞突触前的双极细胞也为神经节细胞突触前的无长突细胞提供输入。窄场无长突细胞显然没有交叉抑制。大多数无长突细胞输入来自 GABAergic 无长突细胞的轴突和树突，可能提供来自经典感受野之外的抑制输入。SB3 细胞通常从多种假定的 OFF 双极细胞中每个双极细胞仅接收一个突触；来自二元突触的无长突细胞的相互突触并不常见。在少数情况下，SB3 神经节细胞突触前的双极细胞也为神经节细胞突触前的无长突细胞提供输入。窄场无长突细胞显然没有交叉抑制。大多数无长突细胞输入来自 GABAergic 无长突细胞的轴突和树突，可能提供来自经典感受野之外的抑制输入。窄场无长突细胞显然没有交叉抑制。大多数无长突细胞输入来自 GABAergic 无长突细胞的轴突和树突，可能提供来自经典感受野之外的抑制输入。窄场无长突细胞显然没有交叉抑制。大多数无长突细胞输入来自 GABAergic 无长突细胞的轴突和树突，可能提供来自经典感受野之外的抑制输入。