Researchers found that distinct cell populations in mouse embryos develop into the forebrain and midbrain versus the hindbrain, supporting a theory that the brain evolved from two neural systems. They also report making functional hindbrain motor neurons from human stem cells.
About a week after conception in mice, Otx2-marked progenitor cells later formed the forebrain and midbrain, while Gbx2-marked cells formed the hindbrain, or brainstem. Similar distinct progenitor cells in chickens, zebrafish and acorn worms point to an evolutionarily conserved pattern. The forebrain handles functions such as language and abstract thought; the hindbrain helps regulate heartbeat, sleep and hunger.
The researchers say they were the first to produce functional hindbrain motor neurons from human pluripotent stem cells, which scientists have struggled to direct into hindbrain neurons. The method could help study brainstem disorders such as spinal muscular atrophy and ALS, and enable earlier, more precise testing of disease hypotheses. UCSF neurobiologist Alex Pollen said it is difficult to rule out that both cell populations arose from one short-lived progenitor.
