Layer-specific brain computations depend on neurons synapsing with specific partners in distinct laminae. In the Drosophila lobula plate, axons of the four subtypes of T4 and T5 visual motion direction-selective neurons segregate into four layers, where they synapse with distinct subsets of postsynaptic neurons. Here, we identify a layer-specific expression of different receptor-ligand pairs of the Beat and Side families of cell adhesion molecules between T4/T5s and their postsynaptic partners. Developmental genetic analysis demonstrate that Beat/Side-mediated interactions are required to restrict innervation of T4/T5 axons and the dendrites of their partners to a single layer. We show that Beat/Side interactions are not required for synaptogenesis. Instead, they contribute to synaptic specificity by biasing cellular adjacency, causing neurons to segregate in discrete layers, restricting partner availability before synaptogenesis. We propose that the emergence of synaptic specificity relies on a competitive dynamic among postsynaptic partners with shared Beat/Side expression to adhere with T4/T5s.

中文翻译：

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偏向细胞粘附组织果蝇视觉运动集成电路


特定于层的大脑计算依赖于神经元与不同层中的特定伙伴的突触。在果蝇小叶板中，T4 和 T5 视觉运动方向选择性神经元的四种亚型的轴突分离成四层，在那里它们与突触后神经元的不同亚群形成突触。在这里，我们确定了 T4/T5 与其突触后伴侣之间细胞粘附分子的 Beat 和 Side 家族的不同受体-配体对的层特异性表达。发育遗传分析表明，需要 Beat/Side 介导的相互作用才能将 T4/T5 轴突及其伴侣的树突的神经支配限制在单层。我们表明 Beat/Side 相互作用不是突触发生所必需的。相反，它们通过偏倚细胞邻接来促进突触特异性，导致神经元在离散层中分离，从而限制了突触形成前伴侣的可用性。我们提出突触特异性的出现依赖于具有共享 Beat/Side 表达的突触后伴侣之间的竞争动态，以粘附 T4/T5。