BrainProducts-Presentation-VEP.ppt
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BrainProducts-Presentation-VEP.ppt
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BrainVisionAnalyzerProfessional,ThemostadvancedandeasytouseEEGanalysispackage!
Welcometo.,Packedwithfeaturestohelpyoumakethemostoutofyourdata.,VISUALLYEVOKEDPOTENTIALDATA,Onthenextcoupleofslideswewanttodemonstratetheeaseandpowerofanalyzingvisualevokedpotentialdatawiththehelpofthesophisticatedtoolsimplementedin,BrainVisionAnalyzerProfessional,Wewilltakeyouthroughallthenecessarystepsfromdatainspectionthroughthefullprocessofdataanalysistothebuildingofgrandaveragesandpeakdetection.,Duringthisprocesswewillperformthefollowingsteps,Grandaveragebuildingforalldatasetsofacategory.,Peakdetectionandexport(N1,N2,P2,P3,LPC).,Averagebuildingforallcategories.,Segmentationofallsignificanteventsintoseparatebranches.,Baselinecorrectionofallsegments.,Artefactrejection(amplitude,gradient,rangeandflatspots).,OcularcorrectionofdataforVEOGandHEOGartefacts.,Globalsegmentationforallsignificantevents.,RereferencingfromCzreferencetolinkedears.,Inspectionoftherawdataforartefacts.,Navigatingandinspectingyourdataset.,Tonavigatewithinyourdataset,youcanusethenavigationbaratthebottomoftheBrainVisionAnalyzerwindow.,Youcanstepforwardandbackwardwithinyourdatasetinincrementsofthewindowsizeorinonesecondincrements.Youcanalsojumptoanydesiredpositionwithinyourdatasetbyclickingintothescrollbarorintothemarkerfieldatthetopofthenavigationarea.,Navigatingandvisuallyinspectingyourdataset.,Asyoucaneasilyseefromthepictureontheleft,thereareanumberofblinkartefactsinourdataset.Youcanalsosee,thatthedatawasobviouslyrecordedwithCzreferenceandthatchannelT7seemstocontainalotofnoise.Letshavealook.,Navigatingandvisuallyinspectingyourdataset.,LetshavealookatapossibleblinkinordertoshowyouthegreatfeaturesBrainVisionAnalyzersupportsforthevisualinspectionofdata.Simplymarkatimerangeinyourdatawithyourmouse.Itwillshowuphighlightedinlightblue.Thenreleasethemousebuttontoopenthecontextmenu.,Navigatingandvisuallyinspectingyourdataset.,Asyoucansee,wehaveanumberofchoicesofwhattodowiththemarkedarea.WecouldchoosetoperformanFFTforourtimerange,displaya3D-maporevenaCSD-map.Wewillchoosethemapoptiontodisplaythetopographicdistributionofthevoltagesforourtimerange.,Navigatingandvisuallyinspectingyourdataset.,Ascouldbeexpected,thevoltagedistributionshowsthetypicalpatternforablinkartefactwithstrongandrathersymmetricalactivityatfrontalsitesandwithpronouncedattenuationoftheblinkpropagationtowardsposteriorsites.Letshavealookatanothertypeofartefactinourdata.,Navigatingandvisuallyinspectingyourdataset.,Aswassaidbefore,channelT7seemstocontainalotofnoise.Thiscouldbedotomovementartefactsfromthejawsaswellastoabadlyseatedelectrodeoranynumberofotherreasons.Letshavealookatthefrequencydistributionwithinthischannel.,Navigatingandvisuallyinspectingyourdataset.,ThistimewemarkedtheentirevisibletimerangewiththemouseandchosetheFFToptionfromtheautomaticallyopenedcontextmenu.ByreleasingthemouseovertheFFTentryweopentheFFTwindowtoviewthefrequencydistributionoftheselectedchannels.,Navigatingandvisuallyinspectingyourdataset.,Asinanyotherwindowwecanchoosethechannelstoviewbymarkingtheirnameswiththemouseandthendouble-clicking.WechosetoviewT7only.ChannelT7containsalotofactivitythroughouttheavailablespectrumwiththeexceptionof50Hertzindicatingthata50Hznotchfilterwasused.,Onceyouaresatisfiedthatyouhaveseenthetypesofartefactspresentinyourdata,youarereadytocorrectorrejecttheseartefacts.-ButfirstletsrereferencethedatasetfromtheCztoA1A2reference(linkedears).,Rereferencingyourdatasettolinkedears.,Justasanyotheroperationyoumightwanttoperformthatchangesthecharacteristicsofyourdataset,rereferencingyourdataisconsideredasaTransformation“withinBrainVisionAnalyzer.Therefore,youcanfindtherereferencingroutinetogetherwiththenumerousotherdatamodifyingoperationsinthemenumainprogrammenuTransformation“.Letschooseitandseewhatitoffers.,Rereferencingyourdatasettolinkedears.,ThefirstwindowoftheNewReferenceentryformrequeststheinformationaboutwhichelectrodeswillformthenewreference.-SincewewanttorereferencetoA1A2(linkedears),wewillchoosejustthesetwo.Obviously,youcouldalsohavechosenallelectrodesforaveragereferenceoranycombinationyoudesire.,Rereferencingyourdatasettolinkedears.,Inthesecondwindowoftheentryformyoucanspecifythechannelsthatthenewreferenceshouldbeappliedtoandwhethertheremainingchannelsthatarenotbeingrereferencedshouldbekept.SinceweusedA1andA2tobuildthenewreference,wewillexcludethemfromreferencingbutkeeptheminthedataset.,Rereferencingyourdatasettolinkedears.,Inthethirdandlastwindowoftheentryformyoucanspecifythenameofthenewreferencechannelandwhetherornottoreusetheoldreferencechannelinformofthenegatednewreference.SinceweusedA1andA2forthenewreference,wechosetonamethenewreferenceA1A2.However,thisnameisarbitrary.,Globallysegmentingyourdatasetintoepochs.,ThenextthingweneedtodoistosegmentourcontinuouslyrecordeddataintoindividualsweepsofeventrelatedEEGepochs.Atthispointwewillnotdifferentiatebetweendifferentstimuluscategories,sincewewanttoperformsomedatapreparationstepsthatshouldbedoneonepochs,butonasmanyepochsaspossible.Letschoosethesegmentationtransformationandseewhatitoffers.,Globallysegmentingyourdatasetintoepochs.,Onceagain,thesegmentationroutineoffersyouathreestepwizardfordataentry.Thefirstpageletsyouchooseamongfourdifferentsegmenationtypes.,Additionally,youcanrequestforthesegmenteddatatobecachedtoafileinordertospeeduplateraccesstoyourdata.,Globallysegmentingyourdatasetintoepochs.,Asyoucansee,wechosetosegmentbasedonmarkerscontainedwithintheEEGdata.Wechoseallmarkersforsegmentationnotdifferentiatingbetweendifferentstimuluscategories.,AtthebottomofthescreenyoucanseethewindowoftheABE,apowerfultoolforcreatingcomplexcombinationsofmarkers.,Globallysegmentingyourdatasetintoepochs.,Thethirdandlastwindowsletsuschoosethestartandstoppointsofoursegmentseitherbasedontime(ms)orondatapoints.Wechoseintervalsrangingfrom500to1548ms.,Asyoucansee,youcanalsochoosetoallowoverlappingofsegmentsandwhethertoskipintervalscontainingbaddata.,Globallysegmentingyourdatasetintoepochs.,LookingcloselyattheBrainVisionAnalyzerwindowwecanseethatacoupleofthingshavechanged.Firstofall,thehistoryexplorerattheleftshowsusthatwehaveperformedtwosteps.,Basedontherawdatawefirstrereferencedthedataandthenweperformedasegmentation.Wecanalsochangethenamesofthesocalledhistorynodes“byhighlightingthemwiththemouseandthenpressingF2.Thisopenesthenameforediting.,Thisiswhatwedidinthepictureontheleft.Wechangedthenamesofthetwonodestoreflecttheparameterswechoseforoperation.,Globallysegmentingyourdatasetintoepochs.,AnotherthingthathaschangedisthelookofthedatawindowontherightoftheBrainVisionAnalyzermainwindow.Insteadofpaper-EEGtypetraceswenowseeanepochedviewofoursegmenteddata.,Atthebottomofourscreenwecanalso,seethatwearenowdealingwithadatasetcomprisedof536segmentsofwhichwearecurrentlylookingatsegmentno.1.,Correctingyourdataforocularartefacts.,Thenextthingwewanttodoistocorrecttheocularartefactswecouldclearlyseeinourinitialdatainspectionstep.BrainVisionAnalyzercorrectsverticalandhorizontaleyemovementartefactswiththehelpoftheregressionbasedcorrectionprocedurebyGratton&ColeswiththeadditionalchoiceofrawaveragesubstractionsuggestedbyGregMiller.Letschoosetheocularcorrectiontransformationandseewhatitoffers.,Correctingyourdataforocularartefacts.,Theocularcorrectionprocedureonlyhasoneinputformwhereyoucanchoosethemethodofcorrectionandwhethertocorrectforverticaland/orhorizontaleyemovements.Youcanalsochoosethechannelstoincludeandwhetherblinkdetectionshouldbeautomaticorsemiautomatic,givingyouthechoicetorejectoracceptindividualblinkforinclusioninthecorrection.,Correctingyourdataforocularartefacts.,InthewindowtotheleftweoverlayedthedatafromchannelFP1afterocularcorrectionwiththedatafromchannelFP1priortocorrectionbysimplydraggingthesegmentationnodeontotheocularcorrectionnode.-Easyaspie.,Asyoucansee,theocularcorrectionfullyeliminatedtheblink.,Correctingyourdataforotherdataartefacts.,Nowthatwehavecorrectedoureyemovementartefactsthenextthingwewanttodoistocorrectanyotherartefactswesawinourinitialdatainspectionstep.BrainVisionAnalyzergivesyouthechoiceoffourdifferentdetectioncriteriabasedonmaximum/minimumamplitudelimits,maximumslope(gradient),voltagerangelimitswithinsegmentsanddetectionbasedonminimumactivitywithinthesegmentsoveratimerange(flatspots).,Correctingyourdataforotherdataartefacts.,Inthefirstwindowofthiswizardyoucanchoosemanualorsemiautomaticaswellasautoma-ticdetectionme-thods.Youalsogetthechoiceofmarkingbadsegementsinstead,ofremovingthemfromthedata.Youcanalsochoosetomarkin-dividualchannelsasbadinsteadofmarkingw
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- BrainProducts Presentation VEP