A Population of Navigator Neurons Is Essential for Olfactory Map Formation during the Critical Period

Abstract

In the developing brain, heightened plasticity during the critical period enables the proper formation of neural circuits. Here, we identify the "navigator" neurons, a group of perinatally born olfactory sensory neurons, as playing an essential role in establishing the olfactory map during the critical period. The navigator axons project circuitously in the olfactory bulb and traverse multiple glomeruli before terminating inperspective glomeruli. These neurons undergo aphase of exuberant axon growth and exhibit a shortened lifespan. Single-cell transcriptome analyses reveal distinct molecular signatures for the navigators. Extending their lifespan prolongs the period ofexuberant growth and perturbs axon convergence. Conversely, a genetic ablation experiment indicatesthat, despite postnatal neurogenesis, only thenavigators are endowed with the ability to establish a convergent map. The presence and the properremoval of the navigator neurons are both requiredto establish tight axon convergence into the glomeruli.