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
17
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 information in paragraph 5 indicates that PCPA was responsible for ______.
选项
A、a lack of sleep
B、the cats’ meowing
C、normal sleeping patterns
D、sleeping about 15 hours a day
答案
A
解析
第五段中关于PCPA的有关描述为Normally cats sleep about 15 hours a day;but Koella’s cats,after receiving PCPA,spent about 30 minutes of each day sleeping.即注射了PCPA后,猫每天只睡30分钟了,相对于以前要睡15小时,少了很多,所以A项正确。
转载请注明原文地址:https://tihaiku.com/zcyy/3184819.html
相关试题推荐
Thewould-besleeperwhorefightshisdailybattlesinbed--orrehearsest
Thewould-besleeperwhorefightshisdailybattlesinbed--orrehearsest
Thewould-besleeperwhorefightshisdailybattlesinbed--orrehearsest
Thewould-besleeperwhorefightshisdailybattlesinbed--orrehearsest
随机试题
Racket,dinclamor,noise,whateveryouwanttocallit,unwantedsoundisA
Throughoutthenation’smorethan15,000schooldistricts,widelydiffering
在无线网络中,天线最基本的属性不包括()。A.增益 B.频段 C.极化
患者男,45岁。右下6缺失,要求行固定义齿修复。检查见缺牙间隙可,牙槽嵴正常,咬
患者女性,68岁。跌倒后造成左股骨颈骨折,行走困难,被收入院。该患者接受人工股骨
开放式基金的特点有()。A:没有预定存续期限B:没有发行规模限制C:可以上市
某地区有两个出租车公司甲和乙,他们推出的出租车的颜色分别是蓝色和红色。经调查发现
某分析师认为美元走势对原油价格可能存在一定影响,他获取了最近的516个交易日的美
当胰岛功能丧失时,仍有降血糖作用的是A.胰岛素 B.二甲双胍 C.格列齐特
水泥混凝土路面滑模摊铺机摊铺速度应根据( )确定。A.板厚 B.碾压能力 C
最新回复
(
0
)