Stanford Study Finds Forebrain and Hindbrain Form Independently, Suggesting Two Squished Nervous Systems

A study conducted by Kyle Loh at Stanford University, published on September 18 in Nature Neuroscience, indicates that the human brain may be composed of two distinct nervous systems that were compressed throughout evolution. The research revealed that during embryonic development, the forebrain and hindbrain develop independently, with two unique populations of brain progenitor cells identified in mouse embryos: one that expresses Otx2 for the forebrain and midbrain, and another that expresses Gbx2 for the hindbrain. This phenomenon was also noted in chickens, zebrafish, and acorn worms, highlighting evolutionary conservation. Furthermore, jellyfish have two nervous systems, suggesting a merger occurred 600–700 million years ago. Loh's team successfully created human hindbrain motor neurons from pluripotent stem cells, though some experts express skepticism about the implications for cell origin and fate.