Level 1 — Absolute Beginner
Scientists at Stanford made a surprising discovery about the brain. They found that the brain is really made of two different parts that grew from different beginnings.
The front part of the brain and the back part of the brain start from different kinds of cells. Cells are the tiny building blocks of the body. The scientists studied baby mice to learn this.
The scientists say these two parts of the brain grew apart from each other over a very, very long time, more than 500 million years.
This new information can help doctors understand sicknesses like ALS. ALS is a serious disease that affects nerves and muscles. Learning about the brain's two parts may help find new treatments.
- discovery
- something new that is found or learned for the first time
- organ
- a part of the body that has a specific job, like the heart or brain
- cell
- the smallest basic unit of a living thing
- evolve
- to change slowly over a very long time
- disease
- an illness that affects the body
- nerve
- a thin fiber in the body that carries messages between the brain and other body parts
- muscle
- a body part that helps you move
- treatment
- something done to help cure or manage an illness
Level 2 — Elementary
Researchers at Stanford Medicine have discovered that what we usually call the brain is actually made up of two separate organs joined together. The finding was published in the journal Nature Neuroscience.
The scientists found that the front part of the brain and the back part develop from two completely different types of starting cells, called progenitor cells. They traced this pattern back through 550 million years of evolution using studies of mouse embryos.
Kyle Loh, a Stanford professor who led the research, explained that his team showed for the first time that the front of the brain comes from a totally different progenitor cell than the back of the brain.
The discovery is not just an interesting fact. The researchers also grew working human hindbrain motor neurons in the laboratory, which could help scientists study serious diseases such as ALS and spinal muscular atrophy, both of which affect the brain stem and nerves.
- researcher
- someone who studies a subject carefully to learn new facts
- progenitor cell
- an early type of cell that can develop into more specialized cells
- embryo
- an animal or human in its earliest stage of development
- professor
- a senior teacher or researcher, usually at a university
- laboratory
- a room or building used for scientific research and experiments
- motor neuron
- a nerve cell that controls muscle movement
- brain stem
- the lower part of the brain that connects to the spinal cord
- spinal cord
- the long bundle of nerves that runs down the back and connects the brain to the rest of the body
Level 3 — Intermediate
A team led by researchers at Stanford Medicine has found that the human brain is not a single unified organ, but rather two distinct organs fused together, each with its own separate evolutionary and developmental origin. The findings were published in the journal Nature Neuroscience.
According to the study, the front and back regions of the brain, roughly corresponding to the forebrain and hindbrain, arise from two entirely different populations of progenitor cells, the early precursor cells that give rise to more specialized tissue. By examining mouse embryos, the researchers traced this two origin pattern across approximately 550 million years of evolutionary history.
Senior author Kyle Loh, an associate professor of developmental biology at Stanford, emphasized the significance of the finding, noting that his team demonstrated for the first time that the front of the brain arises from a fundamentally different progenitor cell than the back of the brain, challenging longstanding assumptions about how the brain forms as a single continuous structure.
Beyond its evolutionary implications, the research carries practical medical significance. The scientists successfully generated functional human hindbrain motor neurons in laboratory conditions, a development that could accelerate research into brain stem disorders such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy, both of which involve the progressive loss of motor neuron function.
- fused
- joined or merged together to form a single entity
- developmental
- relating to the process of growth and change over time
- forebrain
- the front part of the brain, including regions responsible for thought and sensory processing
- hindbrain
- the back part of the brain, connecting to the spinal cord and controlling basic functions
- precursor
- something that comes before and leads to the development of something else
- senior author
- the lead researcher credited with primary responsibility for a scientific study
- longstanding
- having existed for a long time
- amyotrophic lateral sclerosis
- a serious disease that progressively damages nerve cells controlling muscle movement, also known as ALS
Level 4 — Advanced
A Stanford Medicine led research team has upended a longstanding assumption in neuroscience, demonstrating that the human brain is not a singular, continuous organ but rather two distinct organs fused together, each tracing its origin to a separate lineage of progenitor cells that diverged over the course of vertebrate evolution. The findings appear in Nature Neuroscience.
Through detailed examination of mouse embryos, the investigators established that the forebrain and hindbrain arise from entirely different populations of early precursor cells, and by extrapolating this pattern across the evolutionary record, they traced the two origin architecture back roughly 550 million years, suggesting the division predates much of the anatomical complexity later layered atop it.
Kyle Loh, an associate professor of developmental biology and the study's senior author, characterized the discovery as the first demonstration that the anterior and posterior portions of the brain emerge from fundamentally distinct progenitor populations, a finding that complicates the conventional view of the brain as a single, continuously differentiating structure.
The implications extend well beyond evolutionary curiosity. By successfully deriving functional human hindbrain motor neurons under laboratory conditions, the researchers have opened an experimental avenue that could meaningfully accelerate investigations into brain stem afflictions, including amyotrophic lateral sclerosis and spinal muscular atrophy, both of which are characterized by the progressive degeneration of motor neuron function.
- upend
- to overturn or disrupt an established idea or system
- lineage
- a sequence of cells or organisms descended from a common ancestor
- diverge
- to separate and go in different directions from a common point
- extrapolate
- to extend or apply information or conclusions beyond the original scope
- anatomical
- relating to the structure of a living organism's body
- anterior
- situated at or near the front
- posterior
- situated at or near the back
- degeneration
- the gradual decline or worsening of a structure or function over time
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