Lifelong Invertebrate Chordate Central Nervous System Regeneration is Driven by a Migrating Pool of Conserved Neural Stem Cells Program

Adult central nervous systems (CNS) are generally constrained by limited cellular replacement. How regenerating organisms integrate structural maintenance with continuous, cyclic renewal remains unresolved. Here, we leverage the colonial chordate Botryllus schlosseri which completely resorbs and regenerates its entire CNS de novo weekly. Combining indexed single-cell sorting, Smart-seq3 sequencing, spatial mapping, and temporal deconvolution, our studies suggest that this continuous CNS renewal is mediated by an intrinsic pool of lineage-restricted neural stem cells. Single-cell analysis resolved a conserved SOX2/NOTCH1/NEUROG1 prospective progenitor continuum alongside mature excitability-defined neurons. Brain aging drives a phase-specific desynchronization of this regenerative program, inducing early hyper-activation followed by a sudden collapse. Finally, syngeneic transplantation and in vivo tracking show that neural-complex-derived cells persist after vascular delivery and localize to developing bud and neural-associated territories, with injury-associated accumulation near the neural gland. This work establishes a spatiotemporal framework for lifelong chordate CNS renewal and aging.