英语听力文摘 English Digest 315、脑白金到底是什么？

　　脑白金到底是什么？
褪黑素，又名黑素细胞凝集素，俗称为脑白金，是存在于从藻类到人类等众多生物中的一种荷尔蒙，它在生物中的含量水平随每天的时间变化而变化。
Melatonin, sometimes called “the hormone¹ of darkness,” plays an important role in regulating our daily sleep patterns. This hormone is produced by our bodies and in most organismsmelatonin production is higher during the night than during the day.
In addition to their body’s own melatonin, many people take melatoninsupplements in an attempt to help them sleep, fight jet lag or balance out seasonal² affective disorder³.
Melatonin And Memories
But a study by a group of scientists at the University of Houston suggests that melatonin might have a negative impact on the ability to form new memories.
The researchers were interested in how the body’s internal clock affects the formation of new memories. They found that small striped minnows called zebra fish learned very well during the day but very poorly at night, when melatonin levels are higher.
They wondered if melatonin played a role in learning and memory.

　　Melatonin And Learning
They treated zebra fish with extra melatonin during the day, boosting the hormone levels to night-time amounts.
They discovered that high melatonin did not affect learning per se, but dramatically reduced the fishes’ ability to form new memories, or to remember what they’d learned.
Then the scientists inhibitedmelatonin activity in the fish. They did this by blockingmelatoninreceptors with inhibitory drugs. The fishs’ melatonin levels were unchanged, but the ability of melatonin to affect the brain was blocked.
BlockingMelatonin
With melatonin activity blocked, the ability of the fish to form new memories was drastically improved, even at night.
This research has potential benefits for humans. For example, the use of melatoninreceptorblockers could improve performance of night-time cognitive⁴ tasks, helping⁵ people such as night-shift workers or students cramming⁶ for exams.
褪黑素，又名黑素细胞凝集素的荷尔蒙，在调节我们日常睡眠规律中扮演重要角色。人体自身分泌褪黑激素，而且大多数生物夜晚比白天分泌得更多。
此外，一些人通过体外补充褪黑素改善睡眠，缓解飞机时差感、平衡季节性情绪失调。
褪黑素对记忆的影响
但是，休斯顿大学的科学家们研究表明：褪黑素阻碍记忆形成。
研究人员想弄清楚体内生物钟如何影响新生记忆的形成。研究人员发现斑马鱼白天学习能力很好；夜晚却很差，而夜晚褪黑素分泌旺盛。研究人员怀疑褪黑素影响学习和记忆。
褪黑素对学习的影响
白天，研究人员喂给斑马鱼褪黑素，促进斑马鱼夜晚褪黑素分泌。
研究人员发现大量的褪黑素没有直接影响学习本身，但是却很大程度地使斑马鱼的记忆衰退，斑马鱼不记得学过的东西。
接着，科学家们抑制斑马鱼体内的褪黑素的作用：抑制药物阻碍褪黑素受体。斑马鱼褪黑素分泌量没改变，但是褪黑素不能影响不了大脑。
阻碍褪黑素
褪黑素的作用受阻，斑马鱼新生记忆能力明显改善，夜晚也很好。
该项研究带给人类潜在好处。例如，褪黑素受体的阻碍能影响人夜晚的认知能力，那么对于那些夜班工作者和熬夜备考的学生都有所帮助。

1 hormone   

n.荷尔蒙，激素，内分泌

参考例句：

• Hormone implants are used as growth boosters.激素植入物被用作生长辅助剂。
• This hormone interacts closely with other hormones in the body.这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。

2 seasonal   

adj.季节的，季节性的

参考例句：

• The town relies on the seasonal tourist industry for jobs.这个城镇依靠季节性旅游业提供就业机会。
• The hors d'oeuvre is seasonal vegetables.餐前小吃是应时蔬菜。

3 disorder   

n.紊乱，混乱；骚动，骚乱；疾病，失调

参考例句：

• When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。
• It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。

4 cognitive   

adj.认知的，认识的，有感知的

参考例句：

• As children grow older,their cognitive processes become sharper.孩子们越长越大，他们的认知过程变得更为敏锐。
• The cognitive psychologist is like the tinker who wants to know how a clock works.认知心理学者倒很像一个需要通晓钟表如何运转的钟表修理匠。

5 helping   

n.食物的一份&adj.帮助人的，辅助的

参考例句：

• The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
• By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。

6 cramming   

n.塞满，填鸭式的用功v.塞入( cram的现在分词 )；填塞；塞满；（为考试而）死记硬背功课

参考例句：

• Being hungry for the whole morning, I couldn't help cramming myself. 我饿了一上午，禁不住狼吞虎咽了起来。 来自《简明英汉词典》
• She's cramming for her history exam. 她考历史之前临时抱佛脚。 来自《简明英汉词典》