VOA慢速：研究显示长时间太空飞行会影响大脑

Study: Longer Space Flights Affect Areas in Brain

刘立军 供稿

TRANSCRIPT

A new study has found that areas of the brain containing fluid expand when astronauts are on space missions for six months or longer. The American space agency NASA funded the study.

The brain areas are called cerebral ventricles. They contain cerebrospinal fluid, a clear and watery liquid that flows in and around the brain and spinal cord. The fluid helps protect the brain against sudden impact. The fluid also removes waste products.

Researchers based their research on brain scans of 30 astronauts. They found that it took three years for the ventricles to fully return to normal size after long space missions. The results mean that astronauts may need to wait at least three years between longer space missions.

Heather McGregor is a University of Florida brain scientist. She was the lead writer of the study, which appeared in the publication Scientific Reports. She told the Reuters news agency that if the ventricles do not have enough time to get back to normal size, they could have less space to expand on a following trip to space. This could affect the brain’s ability to deal with the changes in gravity that astronauts face.

Rachael Seidler is a University of Florida professor of applied physiology and kinesiology. She was also a writer of the study. She said, “the impact of ventricular expansion is currently not known,” and that scientists need to do more studies on the subject.

She added that the expansion likely compresses the area of the brain around the spaces. To compress means to press, squeeze or make smaller.

On Earth, valves in the body’s vascular system prevent fluid from staying at our feet due to gravity. But in space, without gravity, the valves push the fluid more towards the head. Seidler said this is what likely causes the ventricular expansion. As a result, the brain sits higher in the skull.

The study involved 23 male and seven female astronauts from the U.S., Canadian and European space agencies. The average age of the astronauts was 47. Eight of the astronauts traveled on space shuttle missions that lasted about two weeks. Eighteen were on International Space Station (ISS) missions of about six months. The other four took part in ISS missions that lasted about a year.

The astronauts who went on short missions experienced little or no ventricular size change. A size increase occurred in astronauts after missions of six months or longer. There was no difference in those who went on missions for six months compared to those who went on year-long missions.

The fact that enlargement did not worsen after six months could be good news for future Mars missions. Astronauts may spend two years in microgravity during trips to Mars. The study results are also good news for people thinking about going on short space tourism flights, Seidler added.

Low gravity causes other changes in the human body, as well. These include decreases in bone and muscle mass, some changes to the heart and lung system, and issues with the balance system in the inner ear.

Longer space missions might also increase cancer risk because of greater exposure to solar radiation.

I’m Andrew Smith.

VOCABULARY

1. cerebral ventricles：脑室，脑内含有脑脊液的空腔

2. cerebrospinal fluid：脑脊液，一种清澈的、水状的液体，流动于大脑和脊髓周围，有保护大脑免受突然冲击的作用，同时也清除废物。

3. ventricular expansion：室腔扩张，指室腔内的液体在长时间的太空任务后扩张。

4. compress the area of the brain：压缩大脑区域，指扩张可能会压缩脑部周围的区域。

5. exposure to solar radiation：暴露于太阳辐射下，指长时间的太空任务可能导致暴露于更多的太阳辐射中，增加患癌症的风险。

QUESTIONS

Listen to the news and choose the best answer to each question you hear.

1. What are cerebral ventricles?

A) Areas of the brain containing fluid.

B) Clear and watery liquid that flows in and around the brain and spinal cord.

C) A type of bone and muscle mass.

D) Waste products in the brain.

2. What is cerebrospinal fluid?

A) A type of bone and muscle mass.

B) Fluid that helps protect the brain against sudden impact.

C) Compressed area of the brain around spaces.

D) The fluid that removes waste products.

3. How long does it take for the ventricles to fully return to normal size after long space missions?

A) 6 months.

B) 1 year.

C) 2 years.

D) 3 years.

4. Why may astronauts need to wait at least three years between longer space missions?

A) To have more space to expand on a following trip to space.

B) To deal with the changes in gravity.

C) To wait for the valves to push the fluid towards the head.

D) To give the ventricles enough time to get back to normal size.

5. What may happen if the ventricles do not have enough time to get back to normal size?

A) Astronauts may experience nausea during their next trip to space.

B) The brain’s ability to deal with the changes in gravity may be affected.

C) Astronauts may feel uncomfortable due to fluid staying at their feet.

D) The balance system in the inner ear may be affected.

6. What is likely to compress the area of the brain around the spaces?

A) The valves in the body’s vascular system.

B) Gravity on Earth.

C) Space shuttle missions.

D) Ventricular expansion.

7. Who took part in the ISS missions that lasted about a year?

A) 23 male astronauts.

B) 7 female astronauts.

C) Both male and female astronauts from U.S., Canadian, and European space agencies.

D) Only astronauts over the age of 50.

8. What other changes in the human body does low gravity cause?

A) Issues with the balance system in the inner ear.

B) Increases in bone and muscle mass.

C) Greater exposure to solar radiation.

D) Decreases in heart and lung function.

KEY

1. What are cerebral ventricles?

A) Areas of the brain containing fluid.

B) Clear and watery liquid that flows in and around the brain and spinal cord.

C) A type of bone and muscle mass.

D) Waste products in the brain.

【答案】 A

【解析】细节题。文中提到cerebral ventricles，是指脑室，其中含有液体。

2. What is cerebrospinal fluid?

A) A type of bone and muscle mass.

B) Fluid that helps protect the brain against sudden impact.

C) Compressed area of the brain around spaces.

D) The fluid that removes waste products.

【答案】B

【解析】细节题。cerebrospinal fluid是指脑脊液，可以帮助保护大脑免受突然冲击的影响。

3. How long does it take for the ventricles to fully return to normal size after long space missions?

A) 6 months.

B) 1 year.

C) 2 years.

D) 3 years.

【答案】D

【解析】细节题。研究发现，需要三年时间才能使脑室完全恢复正常大小。

4. Why may astronauts need to wait at least three years between longer space missions?

A) To have more space to expand on a following trip to space.

B) To deal with the changes in gravity.

C) To wait for the valves to push the fluid towards the head.

D) To give the ventricles enough time to get back to normal size.

【答案】D

【解析】推理题。研究发现，需要三年时间才能使ventricles完全恢复正常大小。因此，宇航员可能需要等待至少三年才能再执行长途太空任务。

5. What may happen if the ventricles do not have enough time to get back to normal size?

A) Astronauts may experience nausea during their next trip to space.

B) The brain’s ability to deal with the changes in gravity may be affected.

C) Astronauts may feel uncomfortable due to fluid staying at their feet.

D) The balance system in the inner ear may be affected.

【答案】B

【解析】推理题。如果ventricles没有足够的时间恢复到正常大小，它们在下一次太空旅行中可能会有更少的扩展空间，这可能会影响大脑应对宇航员面临的重力变化的能力。

6. What is likely to compress the area of the brain around the spaces?

A) The valves in the body’s vascular system.

B) Gravity on Earth.

C) Space shuttle missions.

D) Ventricular expansion.

【答案】D

【解析】细节题。ventricular expansion很可能会压缩周围区域的大脑。

7. Who took part in the ISS missions that lasted about a year?

A) 23 male astronauts.

B) 7 female astronauts.

C) Both male and female astronauts from U.S., Canadian, and European space agencies.

D) Only astronauts over the age of 50.

【答案】C

【解析】细节题。参加了约一年的ISS任务的是来自美国、加拿大和欧洲航天局等机构的男性和女性宇航员。

8. What other changes in the human body does low gravity cause?

A) Issues with the balance system in the inner ear.

B) Increases in bone and muscle mass.

C) Greater exposure to solar radiation.

D) Decreases in heart and lung function.

【答案】A

【解析】细节题。低重力导致的其他问题还有人体内耳平衡系统问题。

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