In a study to be published online Sept. 16 in Nature, the researchers succeeded in transplanting self-organizing bits of laboratory-grown human brain tissue called cortical organoids into mice specially bioengineered and bred so that almost all their cerebral cortex was missing. (The cerebral cortex is the outermost “rind” of the brain, to which much of our higher-level functioning, such as cognition, language, attention and decision-making, is attributed.)
The resulting vastly enlarged cavity in the mice’s brains proved to be a hospitable environment. The human tissue survived, thrived, grew—and developed working connections to the mice’s brains and beyond to the spinal cord.