Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom.
Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom.
Phys Rev Lett. 2021 Mar 19;126(11):118101. doi: 10.1103/PhysRevLett.126.118101.
During the development of the nervous system, neurons extend bundles of axons that grow and meet other neurons to form the neuronal network. Robust guidance mechanisms are needed for these bundles to migrate and reach their functional target. Directional information depends on external cues such as chemical or mechanical gradients. Unlike chemotaxis that has been extensively studied, the role and mechanism of durotaxis, the directed response to variations in substrate rigidity, remain unclear. We model bundle migration and guidance by rigidity gradients by using the theory of morphoelastic rods. We show that, at a rigidity interface, the motion of axon bundles follows a simple behavior analogous to optic ray theory and obeys Snell's law for refraction and reflection. We use this powerful analogy to demonstrate that axons can be guided by the equivalent of optical lenses and fibers created by regions of different stiffnesses.
在神经系统发育过程中，神经元会延伸出轴突束，这些轴突束会生长并与其他神经元相遇，从而形成神经网络。为了使这些束能够迁移并到达其功能目标，需要强大的导向机制。定向信息取决于外部线索，如化学或机械梯度。与已被广泛研究的趋化性不同，趋硬性（对基质刚性变化的定向反应）的作用和机制仍不清楚。我们使用形态弹性杆理论来模拟由刚性梯度引起的束迁移和导向。我们表明，在刚性界面处，轴突束的运动遵循类似于光射线理论的简单行为，并遵守折射和反射的斯涅耳定律。我们利用这一强大的类比，证明了轴突可以通过由不同硬度区域产生的等效光学透镜和纤维来引导。
