科学美国人的一篇文章

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1、December20,2006

2、0commentsWhyYouCan'tShoottheSameFoulShotTwiceRepeatedmotionsdifferslightlybecauseofthebrain'splanningmechanismandmusclecontractions.byNikhilSwaminathanPLANNINGSTAGE:Researchersbelievepracticedmotions,likeshootingfreethrows,varyeachtimetheyareperformed,partiallybecauseofvariationsinth

3、ebrain'splanningofthemovementInthelate‘80sandearly‘90s,beforetheClevelandCavaliersbecameLebron^squad,theteam'sfortunesrestedheavilyonthebackofthesteadfastandreliablepointguardMarkPrice・OneofPrice'sclaimstofame:hisrunatCalvinMurphy'sstreakof78consecutivefree-throws-made・InApril1993Pricemissedwhatwoul

4、dhavebeenhisrecord-tyingshotfromthecharitystripe;laterthatmonth,MichaelWilliamsoftheMinnesotaTimberwolveswouldendupbreakingtherecordinagameagainsttheUtahJazz・Mostscientists,whooverthepastdecademayhavehypothesizedwhytheall-timeNBAcareerfree-thrower(hemade90.4percentofhisshots)missedthatcrucialattempt

5、,wouldlikelyhaveblamedtheinconsistencyofso-calledon-linemovements—theneuralactivityandmusclecontractionsthatoccurafterPricebenthiskneesandstartedhismotion.Anewstudyinthisweek*sissueofNeuron,however,reportsthatanotherfactorcameintoplay:thebraindoesnotplantheexecutionofashotinexactlythesamefashioneach

6、stepoftheway."Thepunchlinewith[our]paper/1saysStanfordUniversityelectricalengineerandneuroscientistKrishnaShenoy,"isthatthisisthefirstevidencethatneuralactivity—brainactivitythathappenswellbeforethemovementeverbegins—hasalottosayaboutthevariabil让yortheexactmovementthatyoufregoingtoget.MShenoyandhist

7、eamstudiedtworhesusmonkeysastheymadeasimple,practicedmovement—reachingtotouchatarget—todeterminewhetherso-called"off-line”activityhadanyeffectonthevariabilityofeachmovement.First,themonkeysweretrainedtomakeaquickreachwhentheysawagreentargetandtoexecuteafastermotionwhentheysawaredtarget.Asthemonkeysp

8、erformedthesetasks,theresearchersstudiedindividualneuronsinthepremotorcortexoftheirbrains(theouterlayerofthebrainresponsibleforhigherfunctions,suchasmovementplanning)toseewhethereachnervecellincreased