Meet a mouse whose brain cortex is made up of human cells

Researchers at Stanford University, led by neuroscientist Sergiu Pașca, have successfully integrated human brain organoids into the brains of genetically modified mice. By engineering mice to lack a cortex and hippocampus, scientists created space for human neural tissue to grow and integrate. The study, published in Nature, reveals that these "xenocortical mice" showed improved cognitive performance in maze tests compared to those without human cells. While the research offers potential breakthroughs for studying brain injuries and neurological development, it also raises significant ethical questions. Experts are debating the implications of mixing species' brain tissues, particularly regarding the potential for human-like consciousness in animals. Pașca emphasizes that while this research is valuable for understanding human biology, he draws a firm ethical line against performing similar experiments on primates, where the risk of blurring cognitive boundaries between species is significantly higher.