雅思阅读 9: The Young Neurons of Super-Agers（超级老龄者的年轻神经元）

改编自 Nature / Scientific American（2026年1月）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://www.scientificamerican.com/article/super-agers-with-great-memory-have-more-young-brain-cells/

Reading Passage

A. Among the many unwelcome accompaniments of ageing, the gradual erosion of memory and cognitive function is perhaps the most feared. Not everyone declines at the same rate, however. A small number of individuals — the so-called "super-agers" — reach their eighties, nineties and beyond with memories that outperform those of people decades younger. Why these brains resist the cognitive decay that afflicts most of their contemporaries has long been a mystery. A study published in Nature in 2026, examining brain tissue from deceased donors ranging from young adults to super-agers, points to a surprising biological basis: the continued production of new neurons in the hippocampus — a process known as neurogenesis — appears to be far more active in super-agers than in people whose cognition declined normally, and significantly more active than in patients with Alzheimer's disease. The super-agers who donated their brains had, during life, scored on standardised memory tests at a level typical of people decades younger, despite being in their eighties or older. That definition — memory performance rather than chronological age — is what distinguishes super-ager research from ordinary ageing studies, and it is also what makes the resulting tissue so informative: each donor had already been tested, so the cells could be matched to a measured cognitive profile rather than a guess.

B. The team, led by neuroscientist Orly Lazarov of the University of Illinois Chicago, used single-cell RNA sequencing and epigenetic profiling to identify neural stem cells and immature neurons in post-mortem hippocampal tissue. They found that new neurons constituted only about 0.01 per cent of the cells in the hippocampus — a tiny fraction, but one whose presence or absence tracked closely with cognitive status. Young and old adults with healthy cognition generated neurons at levels appropriate to their age; those experiencing cognitive decline, including individuals with Alzheimer's, showed markedly fewer developing neurons. The super-ager group, however, stood out: it contained an even higher number of immature neurons than the healthy ageing group, though the difference did not always reach statistical significance because each group numbered ten or fewer individuals. The technique itself is relatively new. By sequencing the genetic activity of single cells rather than averaging across a slice of tissue, the team could distinguish genuine immature neurons from other cell types that had previously been mistaken for them. This matters: earlier claims of adult neurogenesis had rested on bulk-tissue measurements that conflated several cell populations, which is one reason the field spent so long in dispute.

C. The finding lands in the middle of one of the longest-running disputes in modern neuroscience. That the adult human brain can generate new neurons at all was, until a few decades ago, an article of faith in the opposite direction. Early twentieth-century neuroscientists, following Santiago Ramón y Cajal's lead, maintained that no new neurons could be born after birth. Mid-century researchers conceded that neurogenesis occurred in childhood but insisted it stopped there. The dogma began to crack in the 1990s, when studies in birds, rodents and non-human primates demonstrated adult neurogenesis in the hippocampus, and subsequent work using protein markers in human tissue suggested that the same process occurred in people. The evidence has remained contested, however, because the protein markers used to identify newborn neurons in post-mortem tissue are not entirely specific — critics argue that they may be expressed by other cell types, not just by developing neurons. The new study's use of single-cell RNA sequencing and epigenetic signatures, Lazarov argues, addresses that objection directly by identifying cells on the basis of their full genetic profile rather than a single protein. The dispute has practical stakes beyond academic pride. If the adult hippocampus genuinely generates new neurons throughout life, then lifestyle choices — exercise, learning, sleep — might influence cognitive reserve through a mechanism that can in principle be measured and boosted. If it does not, then efforts to grow new neurons in old brains are chasing a chimera, and the search for dementia treatments must look elsewhere.

D. Despite the methodological advance, important caveats remain. The sample sizes are tiny — ten or fewer individuals per group — and Maura Boldrini Dupont of Columbia University, an expert in the field, cautions that results drawn from such small cohorts should be treated as preliminary. The study also cannot establish whether active neurogenesis caused the super-agers' superior memory, or whether both are consequences of some third factor — diet, exercise, social engagement, genetic endowment — that was not measured. Lazarov and her colleagues acknowledge that the next step requires functional validation: the techniques used so far identify the cells structurally but cannot prove that the new neurons are actually integrated into working circuits. New imaging methods sensitive enough to detect this activity in living human brains will be required. A further open question concerns where the new neurons, if they are functional, actually go. Animal work suggests they migrate from a narrow strip of tissue deep in the hippocampus and settle into circuits already wired by existing cells; whether human neurons do the same, and at what rate, is not yet settled.

E. The long-term stakes are substantial. If neurogenesis can be shown to support cognitive resilience in old age, it opens the door to pharmacological interventions designed to boost it in patients with Alzheimer's disease and other forms of dementia — conditions that currently affect tens of millions of people worldwide and for which disease-modifying treatments remain scarce. But the super-ager finding also carries a broader message about what the ageing brain can achieve. The old model depicted the brain as a collection of cells that steadily died off and were never replaced; the new picture, in which at least one region continues to produce new neurons throughout life, suggests that the brain retains a degree of regenerative capacity even in extreme old age. Whether that capacity can be therapeutically unlocked is a question that will occupy neuroscientists for years to come. The super-ager phenomenon also carries a quieter, more hopeful message. The old, discouraging view of ageing held that brain cells were simply lost and never replaced, so that decline was a matter of arithmetic: fewer cells, less function. The new view suggests instead that at least one part of the adult brain retains a latent ability to renew itself, and that the super-agers among us are living proof that this ability need not fade with the years.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. The history of a long-running scientific controversy ii. Why super-agers die younger than expected iii. What the new study measured and found iv. The commercial market for anti-dementia drugs v. Limits of the current evidence and next steps vi. Why neurogenesis is impossible in the adult brain vii. Why the finding matters for ageing populations

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

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

5. What distinguishes super-agers from other elderly people? A. They have larger hippocampi than young adults. B. They show more immature neurons in the hippocampus. C. They have no neural stem cells at all. D. They experienced Alzheimer's symptoms earlier.

6. Why has adult neurogenesis been controversial? A. It was discovered only in non-human primates. B. The protein markers used may not be specific enough. C. No new neurons have ever been found in mouse brains. D. The hippocampus cannot be studied after death.

7. What advantage does single-cell RNA sequencing offer? A. It allows researchers to watch neurons grow in real time. B. It identifies cells by their complete genetic profile rather than a single marker. C. It eliminates the need for post-mortem tissue. D. It measures brain activity in living patients.

8. What limitation does the article identify? A. The study proved that neurogenesis directly caused better memory. B. Sample sizes were small and causation has not been established. C. Super-agers were excluded from the analysis. D. Alzheimer's patients were overrepresented in the control group.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. Cajal believed the human brain could not form new neurons after birth.
10. The super-ager group showed statistically significantly more neurons than the healthy ageing group in every comparison.
11. The new neurons made up roughly one per cent of hippocampal cells.
12. Functional validation of the new neurons has already been achieved.
13. Pharmacological treatments to boost neurogenesis are already widely available.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

The production of new neurons in the adult brain is known as (14) __________. In super-agers, this process appears to remain active, offering clues about how the brain might resist (15) __________ decline.

答案与解析

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