fMRI brainvoyager (2)

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1、Cfn.upenn.edu/agvirreIndirectmeasure：Wearenotdirectlymeasuretheneuralactivity,butthefmrisignal(thebloodflow).Sothefmrisignaldoeshavedirectabsoluteinterpretation,mustbecomparedbetweenstatesstudiesclosetogetherintime.(dentalwork,breathing)maketwogroupsd

2、ifferences.Bloodflowresponsecanbeinfluencedbymanyfactors.Makeaclaimsfromonestudyyouhavedone.Ageneralizableresult:Onetypeofgroup,butbecautiontogeneralizeintodifferentgroups(undergraduatestudents&lawyers&teachers&children).extendedtoothergroups.Howcango

3、wrong:alterbloodflow(drgus,hormonalstates,age,gender).Sometimestherearesomeneuralactivitydifferencesindifferentconditions,perhapstherearesomedifferencesinneuralresponesesbutitmaynotbemeasuredbyfirm.Onewaythatcanhappyisthatitisnotabulkchangeorstablecha

4、nge.Sincefmrishowanaverageresponseofthetimespace.Voxel,60,000perhapsbeanimage.Howtomakeaclaimfromawellmakebraintomentalthoughtsofaman.thebrainareafor“love”.Howtomakeinferencementaloperation.·Brainactivityandbehaviour:ØForwardinference:determinewhichbr

5、ainregionisassociatedwithanisolatedbehaviour.Parametricstudy:ØFocalReverseinference:uselocalbrainactivityto(determinewhichmentalstatesareevokedbyacomplexbehaviour)identifymentaloperation.Nootherbrainareaactivated.Justforpain.Goodespecifition.Areyoulyi

6、ng?Mindreadingispossible?LookdifferencesbetweenØMulti-voxelclassification:usedistributedpatternsofbrainactivitytopredictwhichmentalstateisbeingexperienced.SignalandnoiseFouriertransform:analysesignals,powerspectrum(功率谱)。OnlychangesthatareBloodflow(血液流

7、量),bulk:bulk英[bʌlk]n.体积，容量；大多数，大部分；大块vt.使扩大，使形成大量；使显得重要.parametricadj.[数][物]参数的；[数][物]参量的.rotten['rɑtn]adj.腐烂的；堕落的；恶臭的；虚弱的；极坏的adv.非常.confusionn.混淆，混乱；困惑.wrench[rentʃ]n.扳手，扳钳；扭伤；痛苦；歪曲；猛扭vt.扭伤；猛扭；曲解；折磨vi.扭伤；猛扭；猛绞.decoding[,di:'kəudiŋ]n.解码；译码v.破译；译解（deco

8、de的ing形式傅里叶变换（Fouriertransform）是一种线性的积分变换。因其基本思想首先由法国学者傅里叶系统地提出，傅里叶变换原来就是一种变换而已，只是这种变换是从时间转换为频率的变化。这下，你就知道了，傅里叶就是一种变换，一种什么变换列?就是一种从时间到频率的变化或其相互转化。Proton:质子Cfn.upenn.edu/agvirrequiteslowlycanbedetectablebythefmri,changesthatquiterapidlyupsanddo