Telegraph: To study the way fish think, researchers in Japan genetically modified zebrafish larvae so that neurons in their brains gave off fluorescent green light. Because the larvae are transparent, the activity of their brain cells could then be filmed in real time with a microscope and a camera. The researchers, who watched the fish as they preyed on paramecium, were able to determine which networks of brain cells were involved in hunting behavior. By studying the brains of animals, the scientists seek to gain a better understanding of how the human brain works. Their paper appeared online yesterday in Current Biology.