Department of Ophthalmology and Visual Sciences, Washington University in St. Louis, St. Louis, MO, USA.
Department of Neuroscience, Washington University in St. Louis, St. Louis, MO, USA.
Nat Commun. 2024 Apr 5;15(1):2965. doi: 10.1038/s41467-024-46996-0.
VGluT3-expressing mouse retinal amacrine cells (VG3s) respond to small-object motion and connect to multiple types of bipolar cells (inputs) and retinal ganglion cells (RGCs, outputs). Because these input and output connections are intermixed on the same dendrites, making sense of VG3 circuitry requires comparing the distribution of synapses across their arbors to the subcellular flow of signals. Here, we combine subcellular calcium imaging and electron microscopic connectomic reconstruction to analyze how VG3s integrate and transmit visual information. VG3s receive inputs from all nearby bipolar cell types but exhibit a strong preference for the fast type 3a bipolar cells. By comparing input distributions to VG3 dendrite responses, we show that VG3 dendrites have a short functional length constant that likely depends on inhibitory shunting. This model predicts that RGCs that extend dendrites into the middle layers of the inner plexiform encounter VG3 dendrites whose responses vary according to the local bipolar cell response type.
表达 VGluT3 的小鼠视网膜无长突细胞（VG3s）对小物体运动作出反应，并与多种类型的双极细胞（输入）和视网膜神经节细胞（RGCs，输出）相连。由于这些输入和输出连接在同一树突上混合，因此理解 VG3 电路需要将突触在树突上的分布与信号的亚细胞流动进行比较。在这里，我们结合亚细胞钙成像和电子显微镜连接组重建来分析 VG3 如何整合和传输视觉信息。VG3s 接收来自所有附近双极细胞类型的输入，但对快速的 3a 型双极细胞表现出强烈的偏好。通过将输入分布与 VG3 树突反应进行比较，我们表明 VG3 树突具有短的功能长度常数，这可能取决于抑制性分流。该模型预测，将树突延伸到内丛状层中间层的 RGC 会遇到根据局部双极细胞反应类型而变化的 VG3 树突。
