If you avidly played Pokémon as a kid, then it’s likely that a particular region of your brain is alerted when you see the game’s characters now.

A new study from Stanford University proves just that. Researchers showed test subjects hundreds of Pokémon characters and the brains of veteran players reacted more than those less familiar with the video game. What’s even more astounding, though, is that a specific brain fold responded in all the fans—an area behind the ears called the occipitotemporal sulcus.

Scientists already knew that certain areas of the brain are used to identify faces, words, numbers, and even celebrities, and are usually in the same place for large groups of people. A study by Harvard Medical School discovered that for monkeys to develop similar regions, they need to be exposed to objects from a young age. The Stanford researchers had the same question about humans. Pokémon fans became the best subjects since most started playing during their childhood and because the game’s characters are so unique.

The Stanford study upholds theories that early childhood exposure is required for developing assigned brain regions, and from a young age, our brains adjust as a response to experiential learning. Because researchers found that the fold activated by Pikachu, Wobbuffet, and Bulbasaur is the same fold that reacts to images of animals, they think there’s some sort of basic constraints hardwired in the brain that decides how those changes occur.

“What was unique about Pokémon is that there are hundreds of characters, and you have to know everything about them in order to play the game successfully. The game rewards you for individuating hundreds of these little, similar‑looking characters,” Stanford graduate student Jesse Gomez said. “I figured, ‘If you don’t get a region for that, then it’s never going to happen.’’’