In the late 1980s, Canadian master’s student Yoshua Bengio became captivated by an unfashionable idea. A handful of artificial intelligence researchers was trying to craft software that loosely mimicked how networks of neurons process data in the brain, despite scant evidence it would work. “I fell in love with the idea that we could both understand the principles of how the brain works and also construct AI,” says Bengio, now a professor at the University of Montreal.