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. Then
The would-be sleeper who refights his daily battles in bed——or rehearses tomorrow’s problems——finds it hard to fall asleep. Then
admin
2009-02-10
77
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 serotonon 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 were 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 EEG’s showed the brainwave 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 brain stem is located (Paragraph 2 ) _______.
选项
A、in the hypothalamus
B、between the brain and the spinal cord
C、in the transmitter nerve cells
D、between the hypothalamus and the brain
答案
B
解析
第二段中指出“...the brain stem,which joins the brain to the top of the spinal cord...”即脑干连接brain 与 spinal cord,所以B项正确。
转载请注明原文地址:https://kaotiyun.com/show/IL6K777K
0
专业英语四级
相关试题推荐
HaveyouevernoticedacertainsimilarityinpublicparksandbackgardensinthecitiesoftheWest?Aubiquitouswoodlandmix
MyprofessorbrotherandIhaveanargumentaboutheadandheart,aboutwhetherheovervaluesIQwhileIleanmoretowardEQ.We
PASSAGEFOURWhatisthenatureofthispassage,expositoryorsomethingelse?
A、DemandingactionfromtheHeadoftheschool.B、Talkingwiththechild’steacher.C、Changingclassorschoolforthechild.D、
Unlikeanyothercreatureonthisplanet,humanscanlearnandunderstand,withouthavingexperienced.Theycanthinkthemselve
(1)Afteralongdayattheoffice,manyofusfindourselvestakingoutourstressonfriends,children,orsignificantothers.
A、Toconductstudies.B、Tofindpotentialcustomers.C、Topredictpeople’shealthcarecosts.D、Toprovidebetterserviceforcu
Mentalhealthproblemslikefeelinglonelyarenowadaysseenquiteoftenamongcollegestudents.Althoughthemajorityofpeople
Hefailedtocompletelyachievetheaim______bytheteacheratthebeginningoftheterm.
随机试题
背景某市新建科技馆工程,地下2层,地上24层,地上裙房4层,通过正规招投标程序,建设单位最终选定了一个具有相应施工总承包资质的A建筑公司为中标单位,并与其签订了工程总承包合同。施工过程中发生如下事件:事件一:建设单位将该工程金属门窗工程指定分包,并与
肺病及肝的五行传变是
期初余额录入完毕后,应当进行()。
关于激越状态,下列说法中正确的有()。
知识获得的两个环节是()。
事实上,社会上自称“收入低”的群体很多,很少有人对自己目前的薪资水平完全满意。有代表委员认为,若要让人们普遍有“_______”而不是“_______”,应加大收入分配改革的力度,在全社会建立起合理的薪酬体系,同时尽快完善社会保障网。填入画横线部
村里的房子都不是木房子,有些房子涂上了颜色。由此可以推断()。
章太炎
Whendoessleepwalkingusuallyoccur?Whendidtheauthorfallinlovewiththeboy?
中国人很少做手势,而且认为大量手势是多余的。使眼色和吹口哨是很不礼貌的。眼睛接触往往是间接的。两个大拇指向上和拽耳垂(earlobe)是很棒的意思。向外指、竖起小指意思是你什么都不是,质量差或者不擅长。不要用手指招呼某人,因为这个手势是逗小狗的。要想让人注
最新回复
(
0
)