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
Birds that are literally half-asleep—with one brain hemisphere alert and the other sleeping—control which side of the brain rema
Birds that are literally half-asleep—with one brain hemisphere alert and the other sleeping—control which side of the brain rema
admin
2016-04-30
44
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 doping(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.
While sleeping, some water mammals tend to keep half awake in order to_____.
选项
A、alert themselves to the approaching enemy
B、emerge from water now and then to breathe
C、be sensitive to the ever-changing environment
D、avoid being swept away by rapid currents
答案
B
解析
第7段末句提到“也许一边大脑保持清醒是为了让睡眠中的动物不时浮出水面以免被淹死”,B与文中所提及的观点一致。
转载请注明原文地址:https://kaotiyun.com/show/DxG7777K
0
大学英语六级
相关试题推荐
Americanpresidentsseemtoagebeforeoureyes.Butthecommonbeliefthathigh-officestressgraysourleadersfasterthanusu
SevenStepstoaMoreFulfillingJobA)Manypeopletodayfindthemselvesinunfulfillingworksituations.Infact,oneinfourw
莫高窟(TheMogaoCaves/TheMogaoGrottoes),位于敦煌市东南25公里处,东面是鸣沙山,是著名的佛教(Buddhist)艺术宝库。联合国教科文组织(TheUnitedNationsEducational,Scienti
A、She’sannoyedhedidn’tfindthemagazine.B、She’lllookforthemagazineanotherday.C、Sheappreciateshislookingforthem
A、Growingindifferenceofcollegestudentstootherpeople.B、Ever-increasingInternetaddictiononcollegecampuses.C、Sharpdr
A、Alessonrequiresstudents’activeinvolvement.B、Studentsusuallytakeanactivepartinalecture.C、Moreknowledgeiscover
A、Hisparentsareheadinghomeforthetimecoming.B、Hisparentsarecomingbackthistimenextyear.C、Hisparentsliveinano
Cosmeticorplasticsurgeryoftenevokesimagesoffamouspersonalitieswantingtoaltertheirappearancesthrough【B1】______surg
Whatifclothingwasmorethanjustanaccessory?Thegreenmovementisnotnewtofashion,andmanydesignersandmanufacturers
Whatifclothingwasmorethanjustanaccessory?Thegreenmovementisnotnewtofashion,andmanydesignersandmanufacturers
随机试题
远程工作站是______的扩展。()
不属于行政机关依法变更或者撤回已经生效的行政许可的理由是()。
项目资金结构包含()。
A公司从承包方B分包某汽车厂涂装车间机电安装工程,合同约定:A公司施工范围为给水排水系统、照明系统、动力配电系统、变压器等工程;工期5个月不变。A公司按承包方的进度计划编制了单位工程进度计划和施工作业进度计划,经批准后实施。变压器施工前,A公司编
测量银行流动性状况的指标不包括()。
我国国债发行的主要方式是()。
A、 B、 C、 D、 A每个图既是中心对称图形,又是轴对称图形,选项中只有A符合。
A、 B、 C、 D、 B观察题干,图形中封闭空间的个数依次为1、2、3、4、5。由此可知,问号处图形中封闭空间的个数应为6个,B项当选。
阅读下列技术说明,根据要求回答问题1~问题3。[说明]某大学校园网部分拓扑结构如图3-10所示。其中,将连接至交换机Switch1的用户划分到VLAN18,连接至Switch2的用户划分到VLAN22,连接至交换机Switch3的用户划分到
HowardJohnson_____abetterbrandoficecreamandanewwaytosellit.
最新回复
(
0
)