Scientists at Johns Hopkins have grown a first-of-its-kind organoid mimicking an entire human brain, complete with rudimentary blood vessels and neural activity. This new “multi-region brain organoid” connects different brain parts, producing electrical signals and simulating early brain development. By watching these mini-brains evolve, researchers hope to uncover how conditions like autism or schizophrenia arise, and even test treatments in ways never before possible with animal models.