New research suggests that the human brain develops not from a single source of cells, but from two distinct populations that fuse together during embryonic development, challenging a long-established model of how the organ forms.
The findings, published in September in the journal Nature Neuroscience, come from a team led by Kyle Loh, an associate professor of developmental biology at Stanford University. The study found that the front and back parts of the brain arise from different developmental sources that are pushed together to create the appearance of a single organ.
"The brain appears as one organ," Loh told Live Science. "However, we discovered that the front part of the brain and the back part of the brain come from different sources, which are pushed together to create the appearance of a single organ."
The researchers say the discovery may explain why scientists have struggled to grow certain types of brain cells in the laboratory, and could offer new ways to investigate diseases that affect the brainstem, the structure that connects the brain to the spinal cord.
The human brain is divided into three main regions: the forebrain, midbrain and hindbrain, each responsible for different interconnected functions. The traditional view held that the entire central nervous system arises from a single sheet of cells called the neural tube. The new study suggests a more complex origin, with the forebrain and the rest of the brain coming from separate cellular lineages.
Analysis
Why This Matters
- The finding could reshape the fundamental understanding of how the human brain is built, with potential implications for developmental biology and medicine.
- It may help explain why attempts to grow certain brain cell types in labs have been difficult, and could lead to improved methods for creating brain organoids and tissue models.
- The work could open new avenues for studying brainstem disorders, including conditions that affect basic functions such as breathing and heart rate.
Background
The long-standing model of brain development holds that the entire central nervous system emerges from a single population of cells in the neural tube, which differentiates into the forebrain, midbrain and hindbrain. The new study challenges this unitary origin, proposing instead that the front part of the brain (the forebrain) and the rest (midbrain and hindbrain) originate from separate cell populations that meet and fuse. The concept has been debated in developmental biology but had not been clearly demonstrated at the cellular level until now.
Key Perspectives
[Study authors]: The researchers argue that the evidence for two separate sources is strong, based on detailed tracking of cell lineages in developing embryos. They suggest the fused structure masks what is essentially a dual-origin organ.
[Skeptics and other developmental biologists]: Some scientists may await further replication and require additional evidence from different model organisms before abandoning the single-origin model. The findings, while novel, will need to be tested in other species and validated with independent techniques.
[Stem cell and organoid researchers]: If confirmed, the findings could explain why current lab-grown brain tissue often recapitulates only certain brain regions, and could guide efforts to generate a more complete model of the brain.
What to Watch
- Whether other research groups can replicate the findings in mice, primates and human-derived tissues.
- The response from the broader neuroscience and developmental biology communities as the paper is discussed at conferences and in peer commentary.
- Potential applications in regenerative medicine and brainstem disease modelling, if the dual-origin model is accepted.