首页
登录
职称英语
Birds that are literally half-asleep—with one brain hemisphere alert and the
Birds that are literally half-asleep—with one brain hemisphere alert and the
游客
2024-04-04
51
管理
问题
Birds that are literally half-asleep—with one brain hemisphere alert and the other sleeping—control which side of the brain remains awake, according to a new study of sleeping ducks.
Earlier studies have documented half-brain sleep in a wide range of birds. The brain hemispheres take turns sinking into the sleep stage characterized by slow brain waves. The eye controlled by the sleeping hemisphere keeps shut, while the wakeful hemisphere’s eye stays open and alert. Birds also can sleep with both hemispheres resting at once.
Decades of studies of bird flocks led researchers to predict extra alertness in the more vulnerable, end-of-the-row sleepers. Sure enough, the end birds tended to watch carefully on the side away from their companions. Ducks in the inner spots showed no preference for gaze direction.
Also, birds dozing (打盹) at the end of the line resorted to single-hemisphere sleep, rather than total relaxation, more often than inner ducks did. Rotating 16 birds through the positions in a four-duck row, the researchers found outer birds half-asleep during some 32 percent of dozing time versus about 12 percent for birds in internal spots.
"We believe this is the first evidence for an animal behaviorally controlling sleep and wakefulness simultaneously in different regions of the brain," the researchers say.
The results provide the best evidence for a long-standing supposition that single-hemisphere sleep evolved as creatures scanned for enemies. The preference for opening an eye on the lookout side could be widespread, he predicts. He’s seen it in a pair of birds dozing side-by-side in the zoo and in a single pet bird sleeping by a mirror. The mirror-side eye closed as if the reflection were a companion and the other eye stayed open.
Useful as half-sleeping might be, it’s only been found in birds and such water mammals (哺乳动物) as dolphins, whales, and seals. Perhaps keeping one side of the brain awake allows a sleeping animal to surface occasionally to avoid drowning.
Studies of birds may offer unique insights into sleep. Jerome M. Siegel of the UCLA says he wonders if birds’ half-brain sleep "is just the tip of the iceberg (冰山)." He speculates that more examples may turn up when we take a closer look at other species. [br] According to the passage, birds often half sleep because ______.
选项
A、they have to watch out for possible attacks
B、their brain hemispheres take turns to rest
C、the two halves of their brain are differently structured
D、they have to constantly keep an eye on their companions
答案
A
解析
第6段首句提到“新的研究成果为长期以来的一种设想提供了最好的证据,即半脑睡眠机制是动物为防范敌人进化而来的”,A与文章观点一致;B只是讲述了半脑睡眠是怎么回事,并没有告知原因;C文中没有提及;D与文中内容不符。
转载请注明原文地址:http://tihaiku.com/zcyy/3540686.html
相关试题推荐
Birdsthatareliterallyhalf-asleep—withonebrainhemispherealertandthe
Birdsthatareliterallyhalf-asleep—withonebrainhemispherealertandthe
Birdsthatareliterallyhalf-asleep—withonebrainhemispherealertandthe
Birdsthatareliterallyhalf-asleep—withonebrainhemispherealertandthe
[originaltext]Amobileofficeis,quiteliterally,anofficewhichiscapab
Birdsthatareliterallyhalf-asleep—withonebrainhemispherealertandthe
Birdsthatareliterallyhalf-asleep—withonebrainhemispherealertandthe
Birdsthatareliterallyhalf-asleep—withonebrainhemispherealertandthe
Birdsthatareliterallyhalf-asleep—withonebrainhemispherealertandthe
[originaltext]Amobileofficeis,quiteliterally,anofficewhichiscapab
随机试题
Theeffectofthebabyboomontheschoolshelpedtomakepossibleashift
Withoutreadingtherequiredbooksbeforeclasses,studentswillfinditdifficu
TheAmericaneconomicsystemisorganizedaroundabasicallyprivateenterpr
下列不属于安全规章制度的是()。A.技术标准 B.工作标准 C.管理标准
原发性甲状旁腺功能减退的实验室检查常表现为A.低血钙,常低于1.88mmol/L
药材茎呈圆柱形,表面淡紫色或紫色,有纵条纹的是A.益母草 B.淫羊藿 C.茵
居家医学观察期间应采取的防护措施中,错误的是( )。A.早晚各测一次体温,做好
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
中国特色社会主义法律体系由多个层次的规范性法律文件组成。下列属于我国社会主义法律
建设项目的地震安全性评价费应计入建设项目的()。A.可行性研究费 B.研究试
最新回复
(
0
)