Two brains found in one: Stanford study reveals ancient origins
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Researchers at Stanford Medicine discovered the human brain develops from two distinct nervous systems, rather than a single origin as previously believed.
For decades, scientists thought all brain parts came from one progenitor cell early in development. However, Kyle Loh and his team found that the forebrain, responsible for higher-level thinking, and the hindbrain, controlling essential functions like breathing and heartbeat, evolved separately over millions of years. This discovery explains why growing certain brain cells in labs has proven difficult.
The team examined developing mouse embryos and identified two different progenitor cells. One cell, expressing the gene Otx2, forms the forebrain and midbrain. The other, expressing Gbx2, develops into the hindbrain. These cell types maintain distinct developmental paths and unique configurations of DNA packaging, preventing one from becoming the other. This understanding allowed the researchers to successfully grow functional hindbrain motor neurons from human stem cells in a laboratory setting for the first time. This research extends beyond humans.
The team observed the same two-origin brain pattern in chickens, zebrafish, acorn worms, and even jellyfish, suggesting this structure dates back over 550 million years. This breakthrough promises new avenues for studying and potentially treating conditions like spinal muscular atrophy and amyotrophic lateral sclerosis, diseases that affect the hindbrain, and could even inform obesity treatment research.
