Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany.
Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany.
Neuron. 2021 Aug 4;109(15):2457-2468.e12. doi: 10.1016/j.neuron.2021.05.036. Epub 2021 Jun 18.
Segregation of retinal ganglion cell (RGC) axons by type and eye of origin is considered a hallmark of dorsal lateral geniculate nucleus (dLGN) structure. However, recent anatomical studies have shown that neurons in mouse dLGN receive input from multiple RGC types of both retinae. Whether convergent input leads to relevant functional interactions is unclear. We studied functional eye-specific retinogeniculate convergence using dual-color optogenetics in vitro. dLGN neurons were strongly dominated by input from one eye. Most neurons received detectable input from the non-dominant eye, but this input was weak, with a prominently reduced AMPAR:NMDAR ratio. Consistent with this, only a small fraction of thalamocortical neurons was binocular in vivo across visual stimuli and cortical projection layers. Anatomical overlap between RGC axons and dLGN neuron dendrites alone did not explain the strong bias toward monocularity. We conclude that functional eye-specific input selection and refinement limit convergent interactions in dLGN, favoring monocularity.
视网膜神经节细胞（RGC）轴突的类型和眼起源的分离被认为是背外侧膝状体核（dLGN）结构的一个标志。然而，最近的解剖学研究表明，小鼠 dLGN 中的神经元接收来自两个视网膜的多种 RGC 类型的输入。会聚输入是否导致相关的功能相互作用尚不清楚。我们使用体外双色光遗传学研究了功能上的眼特异性视网膜神经节细胞会聚。dLGN 神经元主要由一只眼的输入所主导。大多数神经元都能从非优势眼接收到可检测到的输入，但输入很弱，AMPAAR:NMDAR 比值明显降低。与之一致的是，在整个视觉刺激和皮质投射层中，只有一小部分丘脑皮质神经元在体内是双眼的。RGC 轴突和 dLGN 神经元树突之间的解剖重叠本身并不能解释对单眼性的强烈偏向。我们得出结论，功能上的眼特异性输入选择和细化限制了 dLGN 中的会聚相互作用，有利于单眼性。
