雅思阅读 095: Mini Brains That Age Like Real Ones

Adapted from 'Mini brains kept alive for years appear to age like real brains', Scientific American, August 2026.

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Lab-grown mini brains, called brain organoids, look like small navy beans and have very little in common with a functional human brain. These tiny clumps of neural tissue are grown from stem cells and mimic the earliest stages of brain development. Scientists typically culture organoids for just a few months.

But what happens if they let the tissues develop for longer? In a new study published in Nature, researchers sustained brain organoids in the lab for years, dramatically extending their longevity and opening new opportunities to investigate neural development and disease.

There are parts of human brain development and maturation that scientists really do not know much about, says Paola Arlotta of Harvard University. Hoping to replicate those little-understood stages, the team decided to push further.

Arlotta and her team documented the organoids progress over five years before submitting their research, then continued culturing some for two more years. In a growing medium designed to support neuronal activity, the organoids maintained a diverse collection of brain cells while undergoing changes in gene activity and cell types that mirrored normal human brain development.

They also appeared to mark the passage of time: their DNA accumulated chemical tags called methyl groups, which scientists use to estimate biological age. The organoids showed signs of maturation and even aging like an actual brain.

This suggests that some of the instructions governing brain development are built into cells, allowing them to grow and arrange themselves independently. More mature organoids could be useful for studying neurological disorders that emerge in adulthood, such as schizophrenia, Alzheimers and Parkinsons disease.

Still, Arlotta thinks there is a limit to how far these organoids can mature. They lack blood vessels and large-scale neural architecture, not to mention sensory input from having a body.

Brain organoids also pose bioethical concerns, including the prospect that they may feel pain. But given the vast differences between organoids and a real brain, it is considered highly unlikely that they are even faintly conscious.

Questions 1-5

Choose the correct letter, A, B, C or D.

1. What are brain organoids? A. Real human brains B. Tiny clumps of neural tissue grown from stem cells C. Computer models D. Animal brains
2. How long did researchers culture the organoids? A. A few months B. About one year C. Up to seven years D. Ten years
3. What did methyl groups on DNA indicate? A. The organoids were dying B. The passage of time and biological aging C. Consciousness D. Faulty stem cells
4. Which disease would mature organoids help study? A. Diabetes B. Alzheimers C. Cancer D. Heart disease
5. Why do organoids have limited maturity? A. They run out of nutrients B. They lack blood vessels, sensory input and architecture C. They grow too fast D. Stem cells are too old

Questions 6-10

Do the following statements agree with the information? Write TRUE, FALSE or NOT GIVEN.

6. Organoids look like navy beans.
7. The study was published in Science.
8. The organoids showed changes similar to normal brain development.
9. Scientists believe organoids are likely conscious.
10. Organoids lack sensory input.

Questions 11-13

Complete the summary. Choose ONE WORD ONLY.

The organoids accumulated chemical 11 called methyl groups, indicating aging. Consciousness requires complex networks that process 12 input, which organoids 13.

Answers

1. B 2. C 3. B 4. B 5. B
2. TRUE 7. FALSE 8. TRUE 9. FALSE 10. TRUE
3. tags 12. sensory 13. lack

Key Vocabulary

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