THE REAL PINKY AND THE BRAIN
The human brain is a bit of a black box. Researchers can get a peek with an MRI or biopsy, but they can’t look at brain tissue directly until you’re dead. As for science’s trusty human stand-in, mice and rats? Their brains are not that similar to us super
THE STARTING MATERIALS
It starts with special cells called induced pluripotent stem cells. They’re made by exposing adult cells to transcription factors, which switch speci ic genes on or o . This transforms them from their specialized state back into stem cells that can develop into almost anything.
MAKING A MINI BRAIN
In 2013, scientists put these induced pluripotent
stem cells into a machine called a bioreactor and tossed them in a bath of nutrients and proteins until they turned into brain cells. Amazingly, they self-assembled into complex, multipart, functional structures similar to embryonic human brains — except they are the size of a lentil.
INTO THE MIND OF A MOUSE
Now several research teams managed to implant human mini-brains into the brains of mice and rats. In various experiments, human brain bits connected to blood supply, grew new neurons, and lit up when stimulated.