Stanford University scientists discover that human brain may be two separate organs

For years, scientists believed that the brain developed from a single population of early progenitor cells. However, a groundbreaking study led by Stanford Medicine has revealed that the human brain is actually a combination of two ancient nervous systems that evolved independently over hundreds of millions of years.

The traditional model of brain development suggested that the forebrain, midbrain, and hindbrain all originated from the same source. But the new findings challenge this notion, showing that the brain is constructed from two distinct systems responsible for different functions.

The hindbrain, also known as the brainstem, plays a critical role in controlling essential processes such as breathing, heart rate regulation, and muscle movements required for speaking and swallowing. On the other hand, the forebrain and midbrain are associated with higher cognitive functions like language, abstract thinking, and self-awareness.

This groundbreaking discovery not only sheds light on the fundamental aspects of brain development but also offers new insights into neurological diseases that impact the hindbrain, such as spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS).

Lead researcher Dr. Kyle Roe, along with co-authors Carolyn Dundes and Rayyan Jokhai, found that hindbrain neurons have unique developmental origins distinct from those of the forebrain and midbrain. By isolating and studying hindbrain neurons in a laboratory setting, researchers hope to gain a deeper understanding of these debilitating diseases.

Evolutionary Evidence

The exploration of early embryonic development revealed that hindbrain neurons follow a separate developmental pathway from the rest of the brain regions. Through chromatin analysis, researchers identified distinct gene expression patterns that dictate the fate of brain progenitor cells.

By understanding the distinct origins of the hindbrain, researchers were able to successfully generate functional hindbrain motor neurons from human pluripotent stem cells in a lab setting. These neurons exhibited characteristics of authentic hindbrain neurons, opening new possibilities for studying neurological disorders.

Implications for Disease Research

The discovery of two separate origins of brain development not only offers a new perspective on the brain’s complexity but also provides a promising avenue for investigating diseases like SMA and ALS. By unraveling the mysteries of hindbrain development, researchers aim to develop targeted treatments and regenerative therapies for these conditions.

Collaborating with experts from the California Institute of Technology and the University of California, San Francisco, the research team received support from various institutions, including the National Institutes of Health, National Science Foundation, and charitable foundations dedicated to advancing neuroscience research.