The peripheral nervous system retains the remarkable ability to regenerate following injury. Successful regeneration requires the regrowing nerve to interact with cells in the microenvironment in order to ultimately form synapses with the appropriate targets. What these interactions are, how they change over time, and why neurons fail to reach their targets are all poorly understood. This project will use bioinformatic and genetic tools to dissect these spatiotemporal dynamics. Prior studies in the Lin lab have implicated the protocadherins as potential mediators of regeneration. This proposal will use Merscope, a novel technology capable of assessing gene expression in situ without dissociation. The two lead PIs will: 1) establish a model of neural regeneration using protocadherin mutant mice; and 2) develop new bioinformatic tools to analyze the data. This project will establish a strong foundation for future publications and grant applications.