The Quran says that Allah has sent messengers to all communities. Somewhere in the past a Messenger has spoken about Allah and this is the "collective memory" that isolated peoples have. I have heard about people on remote islands away from "civilisation" that have the concept of one supreme deity (whether they also worship nature or idols) and this can be attributed to them originally coming from a community that had heard the Word of Allah, and not to an inbuilt god brain centre.
If you were to remove the brain centre from a religious person, would they become an atheist? [sarcastic question, no one need answer].