Question

【題目】 We take showers and use the toilet every day to get rid of badly waste. Our brains also need to take a bath every day. How can they do it?

A 2013 study found the answer. Researchers at the LS University of Rochester studied the brains of mice and discovered that they cleaned themselves while the mice slept. A kind of fluid in the brain, called cerebral spinal fluid (CSF, 腦脊液), was found to increase dramatically (顯著地) during sleep, washing away waste proteins that had been building up between brain cells in waking hours.

"This study shows that the brain has different functional stales when asleep and when awake," Maiken Nedergaard, the lead researcher, told NBC News. It also explains why we can't seem to think clearly after a sleepless night while a good night's sleep leaves us feeling sharp and refreshed.

Now a new study, published on Oct 31 in Science, digs a little deeper into our brains' self-cleaning procedure. Instead of mice, this time humans were the test subjects.

Researchers at Boston University, US, monitored (監(jiān)測) the brain waves of 13 healthy adults who were sleeping, using accelerated MRI, which is capable of recording faster changes inside the brain than a regular MRI machine. They found that every 20 seconds, blood flowed out of the brain, making room for a large amount of CSF to come in and "clean". This cycle coincided with(與……一致) the rhythm of the brain's slow waves-an electrical activity that happens when we're in deep sleep.

It's still unknown how these brain activities are connected. But the mere fact that they are connected is exciting enough, since it allows researchers to piece together (拼湊出) possible new explanations for misunderstood diseases.

For example, slow-wave sleep has been proven to play a role in strengthening our memories. This may explain why people with Alzheimer's often have fewer and weaker slow brainwaves. Based on this new study, there could be one more explanation for diseased brains: They are not clean.

Nedergaard, leader of the 2013 study, is also excited about the new findings. "Maybe the most important take-home message is that sleep is a serious thing," she told Scientific American. "You really need to sleep to keep a healthy brain because it links electrical activity to a practical 'housekeeping' function."

【1】When the researchers studied the brains of mice, they found __________.

A.CSF in their brains went down when the mice slept

B.CSF carried away waste proteins in their brain during sleep

C.more waste proteins were produced in their brains when asleep

D.the more CSF was in their brains, the fewer waste proteins were

【2】What did the researchers discover when they monitored human brain waves?

A.The rhythm of the brain was slower than that of CSF.

B.The brains worked more slowly when asleep.

C.Brains were cleaned when blood flowed out.

D.It took 20 seconds for CSF to clean brains.

【3】Which of the following would be the best title for the passage?

A.Connecting Brain ActivitiesB.Cleaning in Your Dreams

C.Having a Good SleepD.Explaining Diseases

Answer 1

【答案】

【1】B

【2】D

【3】B

【解析】

文章大意：我們每天淋浴和使用廁所，以清除身體的嚴(yán)重廢物。我們的大腦也需要每天洗澡，他們怎么能做到呢? 本文對此做了具體的說明。

【1】細(xì)節(jié)理解題。根據(jù)A kind of fluid in the brain, called cerebral spinal fluid (CSF, 腦脊液), was found to increase dramatically (顯著地) during sleep, washing away waste proteins that had been building up between brain cells in waking hours. 大腦中的一種液體，即腦脊液，在睡眠期間會(huì)急劇增加，它會(huì)沖走在清醒時(shí)腦細(xì)胞之間積累起來的廢物蛋白質(zhì)。因此當(dāng)研究人員研究老鼠的大腦時(shí)，發(fā)現(xiàn)腦脊液在睡眠中帶走大腦中的廢蛋白質(zhì)。故答案選B。

【2】細(xì)節(jié)理解題。根據(jù)They found that every 20 seconds, blood flowed out of the brain, making room for a large amount of CSF to come in and "clean". This cycle coincided with(與……一致) the rhythm of the brain's slow waves-an electrical activity that happens when we're in deep sleep. 他們發(fā)現(xiàn)，每隔20秒，血液就從大腦中流出，為大量腦脊液進(jìn)入大腦和“清潔”留出空間．這個(gè)周期正好與大腦慢波的節(jié)律（當(dāng)我們進(jìn)入深度睡眠時(shí)發(fā)生的一種電活動(dòng)）相吻合。因此我們可知腦脊液用20秒清洗大腦，故答案選D。

【3】標(biāo)題歸納題。通讀全文，結(jié)合文章最后一段Nedergaard, leader of the 2013 study, is also excited about the new findings. "Maybe the most important take-home message is that sleep is a serious thing," she told Scientific American. "You really need to sleep to keep a healthy brain because it links electrical activity to a practical 'housekeeping' function." 2013年研究的領(lǐng)導(dǎo)者Nedergaard也對這些新發(fā)現(xiàn)感到興奮。她在接受《科學(xué)美國人》采訪時(shí)表示:“也許最重要的是，睡眠是一件嚴(yán)肅的事情�！薄澳阏娴男枰�睡覺來保持一個(gè)健康的大腦，因?yàn)樗鼘㈦娮踊顒?dòng)與實(shí)際的‘家務(wù)’功能聯(lián)系起來�！� 可知本文主要介紹了在睡眠中是大腦本身如何自動(dòng)清潔其中的廢料，從而讓我們在清醒的時(shí)候感覺狀態(tài)很好的。故答案選B。