首页
登录
职称英语
The would-be sleeper who refights his daily battles in bed -- or rehearses t
The would-be sleeper who refights his daily battles in bed -- or rehearses t
游客
2023-11-13
15
管理
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. [br] 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://tihaiku.com/zcyy/3184820.html
相关试题推荐
Myfatherisaheavysleepernow,butheusedtorarelyoversleep,______he?A、is
Thewould-besleeperwhorefightshisdailybattlesinbed--orrehearsest
Thewould-besleeperwhorefightshisdailybattlesinbed--orrehearsest
Thewould-besleeperwhorefightshisdailybattlesinbed--orrehearsest
Thewould-besleeperwhorefightshisdailybattlesinbed--orrehearsest
随机试题
PASSAGEFOURBrandingtherocks.根据文章最后一段最后两句可知,博茨瓦纳的投资环境则要宽松得多,但是它脱离钻石业可能也是明智的:钻石
Tounderstandthemarketingconcept,itisonlynecessarytounderstandthe
[originaltext]Wildcarrotsprobablyevolvedwiththeotherfloweringplants
Beforethe1850stheUnitedStateshadanumberofsmallcolleges,mostof
投资基金的特点不笆括A.规模经营 B.金融公司 C.专家管理 D.服务专业
碳化深度值测量时,使用适当的工具在测区表面形成深度大于混凝土碳化深度的洞。采用一
垄断形成的原因有( )。A.专利制度 B.规模经济 C.准入制度 D.对
下列关于爆炸性气体的分级和分组的说法中,正确的是()。A.按照最大试验安全
证实性偏见是指过于关注支持自己决策的信息。当我们在主观上认为某种观点正确的肘候,
高压电器及成套装置的主要性能不包括( )。A.通断 B.保护 C.控制 D
最新回复
(
0
)