fMRIbrainvoyager 2文档格式.docx
- 文档编号:20093314
- 上传时间:2023-01-16
- 格式:DOCX
- 页数:11
- 大小:27.36KB
fMRIbrainvoyager 2文档格式.docx
《fMRIbrainvoyager 2文档格式.docx》由会员分享,可在线阅读,更多相关《fMRIbrainvoyager 2文档格式.docx(11页珍藏版)》请在冰豆网上搜索。
Howcangowrong:
alterbloodflow(drgus,hormonalstates,age,gender).Sometimestherearesomeneuralactivitydifferencesindifferentconditions,perhapstherearesomedifferencesinneuralresponesesbutitmaynotbemeasuredbyfirm.Onewaythatcanhappyisthatitisnotabulkchangeorstablechange.Sincefmrishowanaverageresponseofthetimespace.
Voxel,60,000perhapsbeanimage.
Howtomakeaclaimfromawellmakebraintomentalthoughtsofaman.
thebrainareafor“love”.Howtomakeinferencementaloperation.
∙Brainactivityandbehaviour:
Ø
Forwardinference:
determinewhichbrainregionisassociatedwithanisolatedbehaviour.Parametricstudy:
FocalReverseinference:
uselocalbrainactivityto(determinewhichmentalstatesareevokedbyacomplexbehaviour)identifymentaloperation.Nootherbrainareaactivated.Justforpain.Goodespecifition.Areyoulying?
Mindreadingispossible?
Lookdifferencesbetween
Multi-voxelclassification:
usedistributedpatternsofbrainactivitytopredictwhichmentalstateisbeingexperienced.
Signalandnoise
Fouriertransform:
analysesignals,powerspectrum(功率谱)。
Onlychangesthatarequiteslowlycanbedetectablebythefmri,changesthatquiterapidlyupsanddowncannotdetectedbythefmri(notpasswell).Likeevery3/4seconds.Designexperimentsthatwerereallychangesslowly.5minsfaces,5minshouseswouldbebest,butthatisnotthewholestorybecauseofthenoise.
Becauseofthestuckbetweenthehemodynamic(人的血液动力反应)responsesuggestthelowfrequencyoftheexperimentorstimulus,whileintrinsicnoise(固有噪声)suggestthehighfrequencyofthestimulus.Sohowtobalancebetweenthesetwo.
20swouldbeabetterchoice.Blockdesign.20s-30sseconds.Frequencyrepretations.Whatisthenoise?
couldbeheartrate,breathing,brainareas/cortexcommunicated/connectedwitheachother.
Frequencies.
Experimentaldesignhaslowfrequency.Smooththedata.wenormallysmooth6mm.however,thereareotherpeoplewhosmoothdatain8-12mm.donotuseGLM,ifyoudoit,youwantto.
3*3*3brainmodule.Youranotomicaldataishighrevolutionthanyourfunctiondata.
.
fMRI:
lecturesfromFrank:
Presentation:
tellthepresentationtostart----presentationstart—tellthescanstart.
Whatthefinalanalysisaregoingtobe.Plannedeverything,knowinadvancewhatanalysissoftwareyouareGonneuse.
Fmrisafetycourse,youshouldtakethesafetycourse,theywillshowalltheworstthingthatcouldgowrong.Videofrequencyinthescanner,thatisquitedangerous.Minimizethebadthings.
Projector,highresolution,eyetrakler.
Programmetorunthecomputer:
Computerwillcontrolthedeliveryofthestimuli,potentialprogramesthatcouldrunthecomputeris:
presentation(whichistheonewegenerallyuse),eprime,andmatlab,eachoneofthoseisok.Showthingsintothescanner,needthePCandscantalktoeachother.
Oncewegointothebrainvoyager,brianvoyageralwaysgiveanoptiontoskipseveralvolumes.Itisgoodtogetridit.Thereasonis:
Ifyoulookatthestatisticanalysis,allthedatathatinclusesomeconditionsthatsometimesgoestoyourbaseline,andifyourbaselineincludesthesenoiseanditannoysyourbaseline,sojustskipsomevolumesthatdoesnotcontributeatall.Butitisimportanttokeeptrackofthedataifmultipeopleworkonthesamedata.
Presentationlogfile:
itisgoodtohavethelogfilefromthestimulusdelivery.Sothecomputersisshowingthestimulu,itisreallyhandyifkeepingtrackofthelogofwhatisgoingon.Whenitisshowing,whatisupthescanningandwhatishearingfromthescanner.
Youneedhavethelogfilefromthescanningsession.ifyouhavethelogfileandhaveitlogged:
logtheresponse,loginallinformation,youcangobackandcheckeverythingfindeverything(wedidnotlogoneofourparticipantsresponses,andthenwewanttoanalyse,butwedidnothavetheseresponsessincewedidnotlogin),oneword,ifyoudonothavethesestuffatthebeginning,thenyoudonothavetheseatall.
Twowaystodotimingwithbrainvoyager:
uniformtime,2000msTR=2.Ifyouwanttoseethebraininms,youreallyneedtodoitbyyourself,otherwise,thescannerjusttakethebrainevery2s.
Whenthesubjectwasinthescanner,whathappenedtothescannerorcomputer.Attheendofthesessionoratthebeginning(itisuptoyou),werequiretheanatomicdata.Itwilltake4-8minstocollecttheanatomicaldata,thedifferencesbetween4-8minsisthelongertime,thehighercontrastbetweenthewhitematterandthegreymatter.
InFriday,wedid2functionalrunsand1aunotomicrun.Everytime,thereisarunalwaysproduceonefile,butthefunctionalrunsalwaysproduce2files,oneisrawdata,theotherismotioncorrected(moco)data.Wegeneralusetherawdata(frankspreferstousetherawdata,butinsomeothermanuals,someofthemusethemotioncorrecteddata,whichisthesecondoneofeachrun).
Theprocess:
(thesestepsareubtertwined)
Planning,stimuluspresentation,measurement,pre-processingandstatisticanalysis
∙Synchronisations:
scannerwaitsfor7s,untilsignalstobestable,pressbuttonofstimuluscomputerandscanneratthesametime.Soskipfirst1or2volumesthissynchronisationissueneedtobedecidedsincelaterinpreprocessingBVQxwillaskyouifyouwanttoskip.Logfile:
formatistext,every2seconds.#
∙Anatomicalrun:
192sclies,1*1*1mm(thewholehead)
Functionalrun:
32sclices,3*3*3mmandawholebrainvolumeacquiresevery2seconds.
Preprocessing:
∙Anatomicalpreprocessing:
talariakithebrain,filterthebraininthesameway(covertthebraintothetalariakespace)
∙Functionalpreprocessing:
∙Corregistration
CreatPRTfilewhenyouwanttocontrastdifferentconditions.
Brainnormalizationistoputbraininthetalariakispace.Thecontrastofthebrainactivitywhenyouseescrambledpersonandintactperson.
Weusethewizardtoputinthedata.
32slices,ifyouhavesomeareathatyoureallyinterestedininparticular,youmaychangethefunctionalruntothespecificbrain,butwewouldbealittlebitopentoseethewholebrain,toseewhatotherbrainareasmaybeinvolved.Wetrytomeasurethewholebrain.Typically,youcando32sclices,3*3*3voxelsandacquirethewholebrainevery2sceonds.Ifpeoplehavesmallbrains,thatisenough,butifpeoplehavelargerbrain,maybethereissomethinghasmissed.Youhavetheoptionofeithermissingthesopsuperiorfrontalcorxetonthetoporthetemporalcortex.Alltheanotomicdata,everyonealmostgetthesamething.Nomatterthebrainsize.Wherethesekindsofissuesbecomeimportant,youwanttoseewhathappensonaverageabout20brains,hereyouneedtousethenormalization.thatall20brainsatsomehowshouldbealigned.therearetechniquestoallowyou.presentonebrainatatime,yougivepreliminarytheregionyouareinterested..
Butweusuallydoistoaverageallthebraintogether,thensomehowyouneedaspacethatcombineallthesebrains.Allthebrainshavedifferentshapesandsize,evenwetalarikithesecorrectly,cortexbasedalignment..thereisstillalittlechancetohavebrains.
CreatetheVMRanatomicaldata.
CreatetheVMRinthestep9,page41,checkthenumberofsclices(192)-next,checktheresolutionofanatomicalscan/images(256*256).Thenchecktheseslicesandresolutions.---checkthecontrastandbrightness(generallythedefaultisok,sokeeptheoptionsremainthereandthenpressOK).
AftercreatingtheVMR,youcanjustchangetheintensityofthebrain.Whichisinhomogeneitycorrection,V16Tools.OriginalVMR–volumes—inhomogeneitycorrection-loadv6—justclicktheV16file(wecanalsodothisstepbeforetalairach).
CreatetheFMR,Createnamethefirstvmr(therawdata)asR1(here,itisimportanttousethe_underscoretoavoidtheconfusionoffilenames),choosethenumberofvolumesis243,(keepeverythingasdefault).AndthencreateFMRR2,heretheoriginaldesignfortheexperimentis243(thefirstone-first),butfrancesalwaysrunthescanlongerthantheexperimentdesign,andthenjustpressstopwhenitisok.Inordertobeequalastoourdesign,letusgofor243.Thenfornumberofvolumes,letusgofor243.Then,westillnotquitetrustthefirsttwovolumes,sowegoskipthefirsttwovolumes.
Toseethetimecoursemovie:
gototheoptions—timecoursemovies(givethequalitiesofthemovie).
AttachPRTfile:
openthefmrwejustcreated,gotoFMRproperties,choosethefmrrun1—choosethePRTfile(choosetherun1PRTfile)–close
Thenopenthefmrrun2,gotoFMRproperties,choosethefmrrun2—choosethePRTfile(choosetherun2PRTfile)–close
Thus,ourPRTfileisattachedtooutfmr.
Preprocessingthefunctionaldata,closeotherfileandonlykeepthefmropen,gotooptions—preprocessingFmri—clickpreprocessingslicescantimecorrection,3Dmotioncorrection–spatialsmoothing--temporalfiltering(themeanintensityadjustment,whileisnotneedinmostcases,sodon’tchoosethis)---spatialsmoothingistheonegeneralcanbedowna
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- fMRI brainvoyager