首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The would-be sleeper who refights his daily battles in bed -- or rehearses tomorrow’s problems -- finds it hard to fall asleep.
The would-be sleeper who refights his daily battles in bed -- or rehearses tomorrow’s problems -- finds it hard to fall asleep.
admin
2013-04-22
51
问题
The would-be sleeper who refights his daily battles in bed -- or rehearses tomorrow’s problems -- finds it hard to fall asleep. Then he starts worrying about his inability to sleep, which increases his insomnia, which increases his worries, which... In a new development that may help the insomnia to break this vicious cycle, Dr. Werner P. Koella of the Worcester Foundation for the Experimental Biology has discovered a chemical in the brain that may control normal sleep.
The substance, known as serotonin, is one of a number of so-called neurohormones in the brain that researchers suspect play an important part in controlling the mind and the emotions. Such chemicals, researchers have learned, assist in transmitting nerve impulses from one nerve cell to another. Serotonin, Koella notes, is produced in particularly high concentrations in the hypothalamus, the "primitive" lower part of the brain and the brain stem, which joins the brain to the top of the spinal cord and is known to contain the centers controlling the level of transmitter substance in the brain stem and hypothalamus that regulate sleep.
In preliminary experiments, Koella found that giving serotonin to cats produced signs of sleep. Electrode leads were implanted in the cats’ brains and attached to an EEG (electroencephalogram) machine to record the brain waves; next, the serotonin was injected directly into the brain or an artery in the neck. The pupils of the animals’ eyes narrowed and the electroencephalograms showed slow waves characteristic of deep sleep within five to ten minutes.
More recently, Koella deprived cats of serotonin. The animals, again equipped with implanted electrodes, were given PCPA, a drug that blocks the formation of serotonin. They wore then placed in small compartments fitted with one-way mirrors and watched round the clock.
Normally cats sleep about 15 hours a day; but Koella’s cats, after receiving PCPA, spent about 30 minutes of each day sleeping. Most of the time, their EEGs showed the brain wave patterns of arousal. Occasionally the cats would curl up as if to go to sleep, but would soon get back on their feet to wander about. The animals showed signs of irritability and often meowed complainingly after a few days of sleep deprivation, but had normal reflexes. The effects of the PCPA wore off eight days to two weeks after administration of the drug; the cats returned to their normal sleeping patterns as serotonin levels in their brains rose again.
Koella believes that at least some types of chronic insomnia may be caused by a drop in brain-serotonin levels. The Worcester physiologist is now working on chemical ways to raise the brain’s serotonin levels and produce, in his words, "a truly physiological sleeping pill. "Synthetic sleeping pills, such as barbiturates, bring sleep, but at a price: they depress the central nervous system, reduce heart action and respiration -- and they can become habit-forming or even addictive.
In one promising experiment toward the goal of letting the body "make its own pill," Koella has found that administration of 5-hydroxytryptophan, the chemical substance from which the body derives serotonin, will quickly restore a normal sleeping pattern to cats lacking in serotonin.
The language used in this article indicates that Dr. Koella ______.
选项
A、is positive that serotonin controls sleep
B、is quite uncertain whether serotonin controls sleep
C、thinks that serotonin can’t be extracted
D、thinks that serotonin might control sleep
答案
D
解析
A项说Dr. Koella很确定serotonin能控制睡眠,这一点文中已表明是不肯定的;但B项说他十分不确定,也不能这么说;而C项说serotonin不能被提取,实验证明是可以提取的;所以应选D项,Dr.Koella认为,serotonin可能可以控制睡眠。
转载请注明原文地址:https://kaotiyun.com/show/xBQK777K
0
专业英语四级
相关试题推荐
Sometimesyouhavetotravelveryfartogainperspectiveonthingsinyourowncountry.Recently,ItaughtaUNICEF-sponsoredc
Mostpeoplepicturesharks【C1】______huge,powerful,frightening【C2】______readyatanymomentstousetheirsharpteethtoattack
Somedayastrangerwillreadyoure-mailwithoutyourpermissionorscanthewebsitesyou’vevisited.Orperhapssomeonewillca
Howmenfirstlearnedtoinventwordsisunknown;【B1】,theoriginoflanguageisamystery.Allwereallyknowisthatmen,un
Archaeologyasaprofessionfacestwomajorproblems.First,itisthepoorestofthepoor.Onlypaltrysumsareavailablefore
Withgreateffortsofthepeace-lovingpeopleallovertheworld,Iraq______thewar.
Itwasstillquitelightoutofdoors,butinsidewiththecurtainsdrawnandthesmoulderingfiresendingoutadim,uncertain
Nowhereelseintheworld______moreattractivescenerythanisSwitzerland.
Shewalked7milestodayinordertoloseweight;Ineverimaginedthatshecouldwalk_______far.
Cellscannotremainaliveoutsidecertainlimitsoftemperature,andmuchnarrowerlimitsmarktheboundariesofeffectivefunct
随机试题
甲提供三块木料给乙家具厂定制一个衣柜,并约定任何一方违约,须向守约方支付违约金。开工不久甲觉得衣柜样式不够新颖,遂要求乙家具厂停止制作。乙家具厂拒绝停工,继续用剩下的两块木料,按原定样式做好了衣柜。对此,下列说法正确的是()。
静态会计报表一般应根据各个账户的发生额填列,动态会计报表一般应根据有关账户的期末余额填列。()
构成投资项目现金流量的有()。
委托收款是收款人委托银行向付款人收取款项的结算方式。委托收款在同城、异地均可以使用。()
A注册会计师负责审计甲公司2012年度财务报表。A注册会计师遇到下列事项,请代为作出正确的专业判断。(根据2011年考题修订)在确定执行审计工作的前提时,下列有关甲公司管理层责任的说法中,A注册会计师认为正确的有()。
按照文件要求或领导批示,具体处理文件的工作称为()
职业道德,就是从事一定职业的人,在工作和劳动过程中所应遵守的,与其职业活动紧密相关的是()。[辽宁省2007年11月四级真题]
掌握学习理论认为学生能力上的差异并不能决定他们能否成功掌握教学内容,而在于他们()。
自然主义教育思想的作品《爱弥儿》是由以下哪位教育家所著的?()
Ifyouareinterestedinjobcreation—andwhoisn’tthisdays?—youshouldtalktosomeonelikeMorrisPanner.In1999,Pannera
最新回复
(
0
)