Using Neo4j for code analysis, Neolytics is a Ruby gem that records the execution of a block of Ruby code in a Neo4j database. It tracks each step of the execution, objects found along the way, and abstract syntax trees of all Ruby code files involved in the execution. The data can be queried to examine the results, such as examining the execution of a method or running code metrics like cyclomatic complexity. A Rails application is also built on top of Neolytics to provide a user interface for analyzing the data. The tool provides various options for querying and visualizing the data, allowing developers to debug and analyze their code more effectively.