Axons connect neurons together, establishing the wiring architecture of neuronal networks. Axonal connectivity is largely built during embryonic development through highly constrained processes of axon guidance, which have been extensively studied. However, the inability to control axon guidance, and thus neuronal network architecture, has limited investigation of how axonal connections influence subsequent development and function of neuronal networks. Here, we use zebrafish motor neurons expressing a photoactivatable Rac1 to co-opt endogenous growth cone guidance machinery to precisely and non-invasively direct axon growth using light. Axons can be guided over large distances, within complex environments of living organisms, overriding competing endogenous signals and redirecting axons across potent repulsive barriers to construct novel circuitry. Notably, genetic axon guidance defects can be rescued, restoring functional connectivity. These data demonstrate that intrinsic growth cone guidance machinery can be co-opted to non-invasively build new connectivity, allowing investigation of neural network dynamics in intact living organisms.

轴突将神经元连接在一起，建立神经元网络的布线结构。轴突连接主要是在胚胎发育过程中通过高度受限的轴突引导过程建立的，这已被广泛研究。然而，无法控制轴突导向，因此无法控制神经元网络结构，这限制了对轴突连接如何影响神经元网络的后续发育和功能的研究。在这里，我们使用表达可光激活 Rac1 的斑马鱼运动神经元来选择内源性生长锥引导机制，以使用光精确和非侵入性地引导轴突生长。轴突可以在生物体的复杂环境中被远距离引导，压倒竞争性内源性信号并将轴突重定向到强大的排斥屏障以构建新的电路。值得注意的是，可以挽救遗传轴突导向缺陷，恢复功能连接。这些数据表明，可以选择内在生长锥引导机制来非侵入性地建立新的连接，从而可以研究完整生物体中的神经网络动力学。