脑成像介绍(英文版)PPT

BrainImaging某某某BrainImagingBrainimaginginvolvesanalyzingactivitywithinthebrainwhileperformingvarioustasks.Thisallowsustolinkbehaviorandbrainfunctiontohelpunderstandhowinformationisprocessed.Differenttypesofimagingtechniquesvaryintheirtemporal(time-based)andspatial(location-based)resolution（时间分辨率和空间分辨率）.Brainimagingisoftenusedin

cognitiveneuroscience(认知神经学).5ImagingTechniquesTenseissaidtobeadeicticsystem,sincethereferencepointforthesystemisusuallytheactofspeaking.Deicticsystemsarethewaysinwhichaspeakerrelatesreferencestospaceandtimetothe“hereandnow”oftheutterance.Mostgrammaticaltensesystemsallowthespeakertodescribesituationsaspriorto,concurrentwithorfollowingtheactofspeaking.SoinEnglishwehavethethreetenses:past,future,andpresent.SPECT﹠PET(计算机断层扫描和正电子成像术)

SPECTandPETuseradioactiveisotopes(放射性同位素),whichareinjectedintothesubject'sbloodstreamandtakenupbythebrain.Byobservingwhichareasofthebraintakeuptheradioactiveisotope,wecanseewhichareasofthebrainaremoreactivethanotherareas.PEThassimilarspatialresolutiontoFMRI,butithasextremelypoortemporalresolution.SPECTCT扫描时，一束X射线穿过头部，感光胶片形成图像。这种方法可以产生脑部剖面成像。这种方法只显示脑结构，而非脑功能。PETEEG（脑电图）

EEGmeasurestheelectricalfields（电场）generatedbylargepopulationsofneuronsinthecortex（脑皮层）byplacingaseriesofelectrodes（电极）onthescalpofthesubject.Thistechniquehasanextremelyhightemporalresolution,butarelativelypoorspatialresolution.FMRI（功能性磁共振成像）

FMRImeasurestherelativeamountofoxygenatedblood（含氧血）flowingtodifferentpartsofthebrain.Moreoxygenatedbloodinaparticularregionisassumedtocorrelatewithanincreaseinneuralactivityinthatpartofthebrain.Thisallowsustolocalizeparticularfunctionswithindifferentbrainregions.FMRIhasmoderatespatialandtemporalresolution.FMRI功能磁共振成像对流向特定脑区的血液的变化进行检测。它同时提供脑的解剖和功能视图。Opticalimaging（光学成像）Thistechniqueusesinfraredtransmitters（红外线发射器）andreceivers（接收器）tomeasuretheamountoflightreflectancebybloodneardifferentareasofthebrain.Sinceoxygenatedanddeoxygenatedblood（含氧血和脱氧血）reflectslightbydifferentamounts,wecanstudywhichareasaremoreactive(i.e,thosethathavemoreoxygenatedblood).Opticalimaginghasmoderatetemporalresolution,butpoorspatialresolution.Italsohastheadvantagethatitisextremelysafeandcanbeusedtostudyinfants'brains.Opticalimaging

MEG（脑磁图）

MEGmeasuresmagneticfields（磁场）resultingfromcorticalactivity.ItissimilartoEEG,exceptthatithasimprovedspatialresolution.MEGusesSQUIDsensors（SQUID传感器）todetecttinymagneticfields.MEG人的颅脑周围也存在着磁场，这种磁场称为脑磁场。但这种磁场强度很微弱，在电磁场屏蔽室中，将受检者的头部置于特别敏感的超冷电磁测定器中，通过特殊的仪器可测出颅脑的极微弱的脑磁波，形成图形，这种图形便称作脑磁图。它是反映脑的磁场变化，此与脑电图反映脑的电场变化不同。脑磁图对脑部损伤的定位诊断比脑电图更为准确，加之脑磁图不受颅骨的影响，图像