Ever wonder what's going through a fish's mind? While we won't develop underwater telepathy anytime soon, Saitama University can now show us the raw activity. Researchers have learned that injecting zebrafish larvae with green fluorescent protein puts on a light show whenever their neurons fire, illustrating very clearly just which brain regions are active in a given situation, such as chasing down a paramecium for food. The method is more effective and longer-lasting than using dye, and also provides further insight: scientists can clearly spot the neural path when the zebrafish spots and reacts to its prey. As the protein is relevant to humans as well, its longevity could lead to better, longer-term drug testing that shows the cause-and-effect link. Just don't expect as much in the way of mental fireworks.