Ryosuke Cohen — born Yosono Ryosuke in Osaka in 1948 — studied education and began his career as an art teacher in 1974, when he first encountered the world of mail art. His family name, 幸園 (Yosono), was transliterated to "Cohen" on the advice of a friend, and it is under this name that he has become known across the world's postal networks.

Cohen's introduction to mail art came through Canadian artist Byron Black. From that encounter, he made the physical connection of the postal network the foundation of his artistic practice — working to build a worldwide community of artists linked by correspondence.

Launched in June 1985, Brain Cell is the world's longest-running participatory mail art project. Artists from around the globe send stamps, drawings, collages, and other materials to Cohen, who assembles and prints everything onto a single sheet and returns copies to every participant.

The project's name came from Cohen himself: "I called it Brain Cell because when I looked at diagrams of brain structure under a microscope, they looked just like maps of the mail art network. Thousands of neurons intertwined — that is exactly what the world of mail art is." With over 6,000 artists from more than 80 countries, the project has surpassed 1,200 issues and continues today.

In August 2001, Cohen launched the Fractal Portrait Project, traveling to meet Brain Cell participants in person. Journeys through the United States, Italy, Korea, the Netherlands, Belgium, the United Kingdom, and other countries made the network visible through direct human connection.