F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115, USA.
F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115, USA; National Institute of Neurological Disorders and Stroke, 6001 Executive Boulevard Suite 3309, Bethesda, MD 20824, USA.
Curr Biol. 2022 Jul 25;32(14):3110-3120.e6. doi: 10.1016/j.cub.2022.06.023. Epub 2022 Jul 5.
In the mouse visual system, multiple types of retinal ganglion cells (RGCs) each encode distinct features of the visual space. A clear understanding of how this information is parsed in their downstream target, the dorsal lateral geniculate nucleus (dLGN), remains elusive. Here, we characterized retinogeniculate connectivity in Cart-IRES2-Cre-D and BD-CreER2 mice, which labels subsets of on-off direction-selective ganglion cells (ooDSGCs) tuned to the vertical directions and to only ventral motion, respectively. Our immunohistochemical, electrophysiological, and optogenetic experiments reveal that only a small fraction (<15%) of thalamocortical (TC) neurons in the dLGN receives primary retinal drive from these subtypes of ooDSGCs. The majority of the functionally identifiable ooDSGC inputs in the dLGN are weak and converge together with inputs from other RGC types. Yet our modeling indicates that this mixing is not random: BD-CreER ooDSGC inputs converge less frequently with ooDSGCs tuned to the opposite direction than with non-CART-Cre RGC types. Taken together, these results indicate that convergence of distinct information lines in dLGN follows specific rules of organization.
在小鼠视觉系统中，多种类型的视网膜神经节细胞 (RGC) 分别对视觉空间的不同特征进行编码。尽管人们清楚地了解到这些信息在其下游目标——外侧膝状体核 (dLGN) 中是如何被解析的，但仍未完全揭示这一过程的细节。在本研究中，我们使用 Cart-IRES2-Cre-D 和 BD-CreER2 两种小鼠模型，对垂直方向调谐的上下方向选择性神经节细胞（ooDSGC）和仅对腹侧运动调谐的 ooDSGC 亚群的视网膜神经节细胞与外侧膝状体核神经元之间的连接进行了描述。我们的免疫组织化学、电生理和光遗传学实验表明，在外侧膝状体核中，只有一小部分（<15%）的丘脑皮质（TC）神经元接受来自这些 ooDSGC 亚型的初级视网膜投射。外侧膝状体核中具有功能可识别的 ooDSGC 输入的大多数为弱输入，与来自其他 RGC 类型的输入一起汇聚。然而，我们的模型表明，这种混合并不是随机的：BD-CreER ooDSGC 输入与调谐至相反方向的 ooDSGC 的汇聚频率低于与非 CART-Cre RGC 类型的汇聚频率。综上所述，这些结果表明，外侧膝状体核中不同信息线路的汇聚遵循特定的组织规则。
