BrainImaging某某某BrainImagingBrainimaginginvolvesanalyzingactivitywithinthebrainwhileperformingvarioustasks.Thisallowsustolinkbehaviorandbrainfunctiontohelpunderstandhowinformationisprocessed.Differenttypesofimagingtechniquesvaryintheirtemporal(time-based)andspatial(location-based)resolution（時間分辨率和空間分辨率）.Brainimagingisoftenusedin

cognitiveneuroscience(認知神經(jīng)學).5ImagingTechniquesTenseissaidtobeadeicticsystem,sincethereferencepointforthesystemisusuallytheactofspeaking.Deicticsystemsarethewaysinwhichaspeakerrelatesreferencestospaceandtimetothe“hereandnow”oftheutterance.Mostgrammaticaltensesystemsallowthespeakertodescribesituationsaspriorto,concurrentwithorfollowingtheactofspeaking.SoinEnglishwehavethethreetenses:past,future,andpresent.SPECT﹠PET(計算機斷層掃描和正電子成像術)

SPECTandPETuseradioactiveisotopes(放射性同位素),whichareinjectedintothesubject'sbloodstreamandtakenupbythebrain.Byobservingwhichareasofthebraintakeuptheradioactiveisotope,wecanseewhichareasofthebrainaremoreactivethanotherareas.PEThassimilarspatialresolutiontoFMRI,butithasextremelypoortemporalresolution.SPECTCT掃描時，一束X射線穿過頭部，感光膠片形成圖像。這種方法可以產(chǎn)生腦部剖面成像。這種方法只顯示腦結(jié)構，而非腦功能。PETEEG（腦電圖）

EEGmeasurestheelectricalfields（電場）generatedbylargepopulationsofneuronsinthecortex（腦皮層）byplacingaseriesofelectrodes（電極）onthescalpofthesubject.Thistechniquehasanextremelyhightemporalresolution,butarelativelypoorspatialresolution.FMRI（功能性磁共振成像）

FMRImeasurestherelativeamountofoxygenatedblood（含氧血）flowingtodifferentpartsofthebrain.Moreoxygenatedbloodinaparticularregionisassumedtocorrelatewithanincreaseinneuralactivityinthatpartofthebrain.Thisallowsustolocalizeparticularfunctionswithindifferentbrainregions.FMRIhasmoderatespatialandtemporalresolution.FMRI功能磁共振成像對流向特定腦區(qū)的血液的變化進行檢測。它同時提供腦的解剖和功能視圖。Opticalimaging（光學成像）Thistechniqueusesinfraredtransmitters（紅外線發(fā)射器）andreceivers（接收器）tomeasuretheamountoflightreflectancebybloodneardifferentareasofthebrain.Sinceoxygenatedanddeoxygenatedblood（含氧血和脫氧血）reflectslightbydifferentamounts,wecanstudywhichareasaremoreactive(i.e,thosethathavemoreoxygenatedblood).Opticalimaginghasmoderatetemporalresolution,butpoorspatialresolution.Italsohastheadvantagethatitisextremelysafeandcanbeusedtostudyinfants'brains.Opticalimaging

MEG（腦磁圖）

MEGmeasuresmagneticfields（磁場）resultingfromcorticalactivity.ItissimilartoEEG,exceptthatithasimprovedspatialresolution.MEGusesSQUIDsensors（SQUID傳感器）todetecttinymagneticfields.MEG人的顱腦周圍也存在著磁場，這種磁場稱為腦磁場。但這種磁場強度很微弱，在電磁場屏蔽室中，將受檢者的頭部置于特別敏感的超冷電磁測定器中，通過特殊的儀器可測出顱腦的極微弱的腦磁波，形成圖形，這種圖形便稱作腦磁圖。它是反映腦的磁場變化，此與腦電圖反映腦的電場變化不同。腦磁圖對腦部損傷的定位診斷比腦電圖更為準確，加之腦磁圖不受顱骨的影響，圖像