2024剑桥雅思讲义Yes_No_NG_Questions_Strategy_Practice.docx

上传人:王** 文档编号:772493 上传时间:2024-01-14 格式:DOCX 页数:4 大小:17.93KB
下载 相关 举报
2024剑桥雅思讲义Yes_No_NG_Questions_Strategy_Practice.docx_第1页
第1页 / 共4页
2024剑桥雅思讲义Yes_No_NG_Questions_Strategy_Practice.docx_第2页
第2页 / 共4页
2024剑桥雅思讲义Yes_No_NG_Questions_Strategy_Practice.docx_第3页
第3页 / 共4页
2024剑桥雅思讲义Yes_No_NG_Questions_Strategy_Practice.docx_第4页
第4页 / 共4页
亲,该文档总共4页,全部预览完了,如果喜欢就下载吧!
资源描述

《2024剑桥雅思讲义Yes_No_NG_Questions_Strategy_Practice.docx》由会员分享,可在线阅读,更多相关《2024剑桥雅思讲义Yes_No_NG_Questions_Strategy_Practice.docx(4页珍藏版)》请在优知文库上搜索。

1、Whatisdopamine-andisittoblameforouraddictions?Thekeydifferencebetweenhumanbrainsandthoseofotheranimalsisthesizeandcomplexityofourcerebralcortex,thebrainsouterlayerofneuraltissue.Wethereforetendtofocusourattentiononthisarea,believingthatouruniquementallifeisduetothismasterpieceofevolution.However,weo

2、ftenignorethebitsthatarenearlyidenticalbetweenhumansandanimals,suchasthetinygroupofbraincellsthatusethechemicaldopaminetocommunicatewithotherbraincells.Dopamineisoftendescribedasthebrain,spleasurechemica,butitisactuallyinvolvedinalargenumberofphysicalandmentalprocesses.Itisusedbyaclusterofneuronsint

3、hemidbraintotransmitmessagestootherneurons.Thedopamineneuronsaresmallinnumber(0.0006%oftheneuronsinthehumanbrain)andtheyareobservedinallmammalsandevenusimpleanimalssuchasturtles.Inthe1950s,researchersdiscoveredthatratsappearedtoenjoythestimulationofthenervebundlethatlinksthedopamineneuronswiththeirt

4、argetsintheforebrain.Theratswouldlearntopressaleverforthiskindofstimulation,and,leftunchecked,woulddosothousandsoftimesinaday.Asimilar(andwhollyunethical)experimentwasperformedin1970onahumanpatient.Liketherats,thepatientlearnedtopressabuttontostimulatethedopaminenervebundle,pressingthebuttonupto1500

5、timesoverthecourseofathree-hoursessionandreportingfeelingsofpleasureduringthestimulation.Sincethen,studieshaveshownthatthedopaminesystemcanbeactivatedbyawiderangeofpleasantexperiences,suchaseating,sexualintercourse,gettingrevenge,winningvideogames,listeningtomusic,earningmoneyandreadingfunnycartoons

6、.Thedopaminesystemalsorespondsrobustlytoaddictivedrugs,includingopiates,alcoholandcocaine.Thesedrugscanevokestrongeractivationthannaturalrewardsand,unlikenaturalrewards,theydonotcausesatiety.Astraightforwardinterpretationofthesefactsisthatthedopaminesystemisapleasurepathwayinthebrain.Thispotentially

7、explainswhyanimalsandpeoplewouldbewillingtopressbuttonsorpushleverstoactivatethedopamineneurons.Itmightalsoexplainwhysomedrugsaresoaddictive.Thestrongandprolongedactivationinducedbydrugscanactasa“super-reward,makingdrugsevenmoredesirable.However,manymentaleventsoccurnearthetimeofareward,includingcha

8、ngesinmotivation,arousal,attention,emotion,andlearning.Forexample,imaginepassingbyavendingmachinethatofferssweets.Ifyouaremotivatedbyhunger,yourattentionwillbedrawntothemachineandyouwillbecomemorealertasyouapproachit.Onceyouhaveeatenthesweets,youexperiencepleasure,yourbrainlearnstoassociatethevendin

9、gmachinewithreward,andyourhungerdecreases.Itislikelythatthedopaminesystemisinvolvedinmanyoftheseprocessesratherthanjustpleasureperse.Oneofthemostimportantaspectsofdopaminefunctionislearning.Researchersbelievethatdopamineneuronschangetheiractivitywhenexpectationsaboutrewarddonotmatchthereality,signal

10、linga,rewardpredictionerror*thatdriveslearning.Forinstance,dopamineneuronsareactivatedbyunanticipatedrewards,buttheyaresuppressedwhenexpectedrewardsfailtomaterialise.Eventsfollowedbyincreasesindopamineactivationbecomeassociatedwithreward,andthosethatarefollowedbydecreasesarelinkedwithdisappointment.

11、Iftheenvironmentisunchanging,allourbrainsneedtodotoobtainrewardistoengageinactionsthatactivatethedopamineneuronsandavoidtheonesthatsuppressthem.Itishighlyunlikelythatwehavemuchawarenessofthelearningthatdopamineactivationinduces,suchasmakingusattachedtothingsweunknowinglyassociatewithdopamineactivati

12、on.Thislackofawarenessmightexplainwhypeopleoftenmakeseeminglyirrationalormaladaptivechoices.Imagineadrugaddicttakingcocaine.Becausethepleasurefromcocainedoesnotsatiatelikeanaturalreward,thedopamineactivation,andhencedrug-inducedlearning,occurswitheachpuffofthecrackpipe,makingtheactualpipeanobjectwhi

13、chtheaddictisdrawnto.Canbrainresearchbeusedtoovercometheeffectsofdopamineinaddiction?Neuroscientistsareactivelypursuingthecreationofdrugsthatblockthelearninginducedbydopamineinaddiction.However,theyhavehadlimitedsuccess,foritisdifficulttocreateadrugthatblocksthelearningwithoutalsoblockingotherfuncti

14、onsofdopamine,suchasfeelingalert,motivatedandhappy.Dopamine-inducedlearningiscertainlynotthewholestorybehindaddiction,butitdoessuggestthatweshouldconsiderwhetheraddictionissomethingthathumanreasoningonitsowncanovercome.Thesamemightverywellalsoapplytoothereverydayfailuresofwillpower,suchasovereating.

15、Ourspecialcerebralcortexmaybeincontrolofouractions,butourprimitivedopaminesystemmayverywellserveasitsteacher.Source:http:Questions1-10Dothefollowingstatementsagreewiththeclaimsofthewriterinthepassage?YesifthestatementagreeswiththeclaimsofthewriterNoifthestatementcontradictstheclaimsofthewriterNotGiv

16、enifitisimpossibletosaywhatthewriterthinksaboutthis1. Therearemanywaysinwhichhumanbrainsdifferfromthebrainsofotheranimals.2. Thecellsinthebrainthatmakeuseofdopamineasameansofcommunicationareuniquetohumans.3. Dopaminecanbecharacterisedinotherwaysthanassimplyachemicalinvolvedinthesensationofpleasure.4. Theexperimentcarriedoutonahumansubjectin1970wasunethicalbecausei

展开阅读全文
相关资源
猜你喜欢
相关搜索

当前位置:首页 > 外语学习 > 雅思/LSAT

copyright@ 2008-2023 yzwku网站版权所有

经营许可证编号:宁ICP备2022001189号-2

本站为文档C2C交易模式,即用户上传的文档直接被用户下载,本站只是中间服务平台,本站所有文档下载所得的收益归上传人(含作者)所有。装配图网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私,请立即通知装配图网,我们立即给予删除!