Alice Stanton’s friends call her a brain engineer. It’s an apt title for the scientist who developed the first complete tissue model of the human brain, with blood vessels and all six major cell types, including neurons and immune cells. She also has created a brain-on-a-chip, a version of her full-size model that’s smaller than a mustard seed. Stanton wants to use these mini brains to better understand neurological diseases such as Alzheimer’s and Parkinson’s so researchers can develop...