Technological advances in axonal regeneration and structural plasticity: optogenetics, single-cell omics, and tissue clearing.

Modern techniques have provided novel insights into the molecular and structural characteristics of neurons and glial cells in the central nervous system (CNS). Over the past decade, advancements in optogenetics, single-cell RNA sequencing, and tissue clearing have enabled unprecedented resolution, sensitivity, and throughput, driving progress in CNS repair. In this review, we focus on how these technologies have illuminated the dynamic structural and functional behaviors of axons, from degeneration to regeneration, following spinal cord and optic nerve injuries. Optogenetics offers precise spatiotemporal control of neuronal activity, revealing how targeted stimulation influences axonal growth and circuit reorganization. Single-cell omics uncovers the heterogeneity of axonal regenerative capacity among neuronal subtypes and identifies novel regeneration-associated genes (RAGs) that orchestrate axonal structural remodeling. Tissue clearing and 3D imaging allow direct visualization of axonal trajectories, growth cone morphology, and pathfinding errors in intact tissue, overcoming limitations of conventional histology. Together, these approaches have provided important insights into axonal dynamics and have opened new avenues for promoting functional recovery after CNS injury.