“Scientists around the world are implanting tiny blobs of bioengineered human brain-like tissue, to understand brain development and disease, creating chimeras. WSJ’s Daniela Hernandez explains how they work and connect up to living rodent brains, plus the ethical issues, including the potential to change animal cognition, consciousness and brain health. 0:00 Intro 0:15 How do brain organoids work? 0:55 Why do scientists chimeras? 2:08 What have scientists learned? Neurons look different 3:03 What have scientists learned? They affect behavior 3:20 What are the limitations? 3:33 Do their potential research benefits justify the means? 4:15 Conclusion ».