Approximately half of the human brain consists of myelinated axons. Central nervous system (CNS) myelin is made by oligodendrocytes and is essential for nervous system formation, health, and function. Once thought simply as a static insulator that facilitated rapid impulse conduction, myelin is now known to be made and remodeled in to adult life. Oligodendrocytes have a remarkable capacity to differentiate by default, but many aspects of their development can be influenced by axons. However, how axons and oligodendrocytes interact and cooperate to regulate myelination in the CNS remains unclear. Here, we review recent advances in our understanding of how such interactions generate the complexity of myelination known to exist in vivo. We highlight intriguing results that indicate that the cross-sectional size of an axon alone may regulate myelination to a surprising degree. We also review new studies, which have highlighted diversity in the myelination of axons of different neuronal subtypes and circuits, and structure-function relationships, which suggest that myelinated axons can be exquisitely fine-tuned to mediate precise conduction needs. We also discuss recent advances in our understanding of how neuronal activity regulates CNS myelination, and aim to provide an integrated overview of how axon-oligodendrocyte interactions sculpt neuronal circuit structure and function.

人脑约有一半由有髓神经的轴突组成。中枢神经系统（CNS）髓磷脂由少突胶质细胞形成，对于神经系统的形成，健康和功能至关重要。曾经被简单地认为是促进快速脉冲传导的静态绝缘体，如今已经知道髓磷脂可以被制成并重塑到成人生活中。少突胶质细胞具有默认情况下的卓越分化能力，但其发育的许多方面都可能受到轴突的影响。然而，尚不清楚轴突和少突胶质细胞如何相互作用和协作以调节CNS中的髓鞘形成。在这里，我们回顾了我们对这种相互作用如何产生已知存在于体内的髓鞘形成的复杂性的理解方面的最新进展。我们强调了有趣的结果，这些结果表明轴突本身的横截面尺寸可能将髓鞘形成调节到令人惊讶的程度。我们还审查了新的研究，这些研究突出了不同神经元亚型和回路的轴突的髓鞘形成以及结构-功能关系的多样性，这表明可以精细地调节髓鞘的轴突来介导精确的传导需求。我们还讨论了我们对神经元活性如何调节中枢神经系统髓鞘形成的理解方面的最新进展，并旨在提供轴突-少突胶质细胞相互作用如何雕刻神经元回路结构和功能的完整概述。这表明可以精细地调节有髓轴突，以介导精确的传导需求。我们还讨论了我们对神经元活性如何调节中枢神经系统髓鞘形成的理解方面的最新进展，并旨在提供轴突-少突胶质细胞相互作用如何雕刻神经元回路结构和功能的完整概述。这表明可以精细地调节有髓轴突，以介导精确的传导需求。我们还讨论了我们对神经元活性如何调节中枢神经系统髓鞘形成的理解方面的最新进展，并旨在提供轴突-少突胶质细胞相互作用如何雕刻神经元回路结构和功能的完整概述。