Human brain may have formed from two separate organs
Summary and headline written by AI from the source article. How we work
Stanford University researchers discovered that the human brain may have developed from two distinct neural systems that merged over millions of years of evolution.
The team found that the forebrain and midbrain originate from one embryonic cell lineage, while the hindbrain, responsible for automatic functions, develops from a separate lineage.
They observed this division as early as 7.5 days after conception in mouse embryos, with two groups of neural progenitors expressing different genes, Otx2 and Gbx2, which commit them to either the front/middle or hindbrain. Researchers recreated these early states using human stem cells and confirmed the cells resisted changing to the other region’s fate, showing their developmental paths diverged early.
This division isn’t unique to humans; the team also found similar neural programs in species including macaques, chickens, zebrafish, and acorn worms, suggesting the split occurred between 550 and 600 million years ago. This new understanding of brain development allowed the researchers to successfully grow specific hindbrain motor neurons from human stem cells, a feat previously difficult to achieve.
These lab-grown neurons could prove useful for studying diseases like amyotrophic lateral sclerosis and spinal muscular atrophy, which affect motor neurons and impact functions like swallowing and breathing.
