GoKawiilStanford researchers grow mice with brains nearly half made of human neurons
Stanford scientists genetically engineered mice lacking a functioning cortex, then implanted human neurons derived from reprogrammed skin cells into the empty space. The transplanted cells multiplied from a few hundred to several million and wired themselves into the mouse brain, with the animals behaving largely normally despite the human tissue making up nearly half their brain volume by some measures. The findings were published in Nature.