2023學(xué)年完整公開(kāi)課版Lecture9Binocularandmotionperception

Lecture9:

BinocularVision,Depth&MotionPerceptionBinocularVisionTheRetina(ganglioncellreceptivefields)SomewhereinCortexColorShapeMovementButdon’tforget!We’llhavetodothis3times,andmaybea4th!Preyanimal:

eyesonsideofthehead-

eacheyegetsadifferentimageAnincoherentimagewouldbeproducedinthebrainNormally,visualpathways‘cross’–thelefthalfofthevisualfieldisprocessedintherighthalfofthebrain,andviceversa.WHY?Well,withthankstothecleverCajal,let’shavealookatwhatwouldhappenifthevisualpathwaysdidNOTcross…Thevisualthalamushas6layers,3foreacheye.ColorShapeMovementHumanORPredator:

Two(slightlydifferent)PicturesoftheSameThing

Yourocularmusclesensurethattheimageineacheyeissplitequallyacrossnasalandtemporalretinasd=opticnervec=opticchiasmg=thalamusRv=rightvisualctxWhathappenswhenyoucrossyoureyes?

Nowtheimageisprojectedontoonlyonehalfoftheretina.

Twoimportantthingshappen…Thepurposeofthetwoimagesistogenerate‘binoculardisparity’,whichisgreaterwhenobjectsareclosetous.Thevisualsystemestimatesthedepthofanobjectbasedonbinoculardisparity.ShapeColorMovementColorShapeMovement3‘channels’leavetheRetinaEachchannelisdestinedforitsowncorticalprocessingareaFaceProcessingItallbeginshere…VisualProcessingInCortexThebasicorganizationandfunctionofprimaryvisualcortex(thehypercolumn!).Thesynapticmechanismsusedtoproducecellsthatcouldrespondtocomplexshapesormovement.PerceptionofdepthandMotion(whytheretinacan’tknowwhethersomethingismovingornot).lightReview:WhatisleavingtheRETINA?Eye-specificLayersEye-specificColumnsASurprise:TheFirstElementsofShapeAreLittleBarsretinathalamuscortexretinathalamuscortexretinathalamuscortexV1CorticalCellInputCellsretinathalamuscortexretinathalamuscortexV1CorticalCellInputCellsPrimaryVisualCortexisaVASTARRAYofHYPERCOLUMNS

(thisexampleshowsthreehypercolumns)Eachcolumnrespondstoa‘bar’ofcontrastwithaspecificorientation(OrientationColumns–specifiedbyresponse).OrientationColumnsareorganizedintoLeftandRighteyegroups(OccularDominanceColumns–specifiedbyinput).OrientationColumnsOccularDominanceColumns123Whatdoesthismean?AsingleHypercolumncorrespondstoONEpointinvisualspace.EverythingthatyoucouldpossiblyseeinthatONEpointisalreadyrepresentedinthecorrespondingHypercolumn.Inotherwords,everythingyoucanseeisalreadyrepresentedinPrimaryVisualCortex.Ifitisn’tthere,youcan’tseeit.OrientationColumnsOccularDominanceColumns123PointinvisualspacePointinvisualspaceLRLRRighttemporalretinaLeftnasalretinaRightPrimaryVisualCortexWhathappenswhenIshowyouan‘X’inyourLEFTvisualfield?Whatdoesthevisualsystemdowithalltheselittlebars?retinathalamuscortexV1CorticalCellInputCellsSomewheredownstream,these4‘bar’detectingresponsesconvergeonasingle‘square’detectingcell3‘dot’detectingcellsconvergeonasingle‘bar’detectingcellinprimaryvisualcortex(V1)ExampleofresponsesofaV2corticalneurontovisualstimuliHedgeandVanEssen,20003‘square’detectingcellsconvergeonasingle‘cube’detectingcelllocatedinatertiaryprocessingarea–etc.,etc.,…Geonshypothesizedtobe‘3DShapePrimaries’ShapeColorMovementColorShapeMovement3‘channels’leavetheRetinaEachchannelisdestinedforitsowncorticalprocessingareaFaceProcessingItallbeginsherewithlittledotsofcontrast…EffectsofExperienceonOcularDominanceColumnsNativismvs.Empricism‘Seeing’OcularDominanceColumnsPutTracerinOneEyeEffectsofExperienceonOcularDominanceColumnsNativismvs.EmpricismEffectsofExperienceonOccularDominanceColumnsEffectsofExperienceonOccularDominanceColumnsRaiseAnimalInTheDarkNormalDevelopmentAdultWhatHappensIfSightReturnsinAdulthood?RaiseAnimalInTheDarkAdultNoDepthPerceptionPossibleEffectsofExperienceonOrientationSpecificityMotionPerceptionPerceivingmovementHowdoweperceivemovement?Howcomeweperceivemovementevenwhenthingsarenotactuallymoving?ch832FourdifferentwaysofperceivingmovementRealmovementTheobjectisphysicallymovingApparentmovementDisplacementofobjectsInducedmovementMovementaftereffectch833Patternsofconnectionscanbeusedtomakea‘movingbar’detectingcellDelaylines...Iseeaverticalbarofcontrastmovinglefttoright!Whathappensifthebarismovingtoofast?Delaylines...Wha!!??WhyMotionCan’tBe‘Sensed’StarMovesRightEyeMovesRightThePatternofImageMovementontheRetinaistheSame!FunctionsofMovementPerception-continuedPerceivingobjectsMovementofobjectsortheobserver’smovementthroughobjectshelpperceivethe3DorganizationofstimuliKineticdeptheffect-movementofanobject’s2-Dshadowcanchangeintoperceptionofa3-Dobject(structure-from-motion)Perceptualorganizationch838Figure9.4SetupsimilartotheoneusedbyWallachandO’Connell(1953)todemonstratethekineticdeptheffect.ch839Structure-from-motionDemonstration:http://www.cs.ubc.ca/nest/imager/contributions/flinn/Illusions/Illusions.htmlch840MotionparallaxDemonstrationDepthperceptionbymotionYouTube/videoplay?docid=-5983729407150064898&q=motion+parallax&total=43&start=0&num=10&so=0&type=search&plindex=2ch841ch842ch843ch844ch845SituationsleadingtoMovementPerceptionAnobjectmoves,andtheobserverisstationaryimagethatmovesontheobserver’sretinaAnobjectmoves,andtheobserverfollowstheobjectwithhisorhereyesimageisstationaryontheretinaAnobservermovesthroughastationaryenvironmentenvironmentisperceivedasstationarych846ch847CorollarydischargetheoryMovementperceptiondependsonthreesignalsMotorsignal(MS),senttotheeyemusclesCorollarydischargesignal(CDS),whichisacopyofthemotorsignal.Imagemovementsignal(IMS),whichoccurswhenanimagestimulatesthereceptorsasitmovesacrosstheretina.ch848ch849Whenyoupushyoureyelid,youreyeandtheimageyougetmovetoo,butyoudon’tperceive“motion.”CDSorIMSMovementperceptionCDSAndIMSNomovementperceptionCorollarydischargetheoryWheneitherCDS(corollarydischargesignal)

or

IMS(imagemovementsignal)issenttothestructurecalled“Comparator”,weperceivemotion.MovementisnotperceivedwhencomparatorreceivesinputfromBothCDSandIMS.ch850ch851MovementperceptionMovement

perceptionNoperceptionPhysiologicalEvidenceforCorollaryDischargeTheoryDamagetothemedialsuperiortemporalarealeadstoperceptionofmovementofstationaryenvironmentwithmovementofeyesch852ch853Neuronsthataresensitivetoaspecificdirectionofmotion.Inhibitoryconnectionsch854ch855ch856ch857FunctionsofMovementPerception-continuedPerceivingobjectsMovementofobjectsortheobserver’smovementthroughobjectshelpperceivethe3DorganizationofstimuliKineticdeptheffect-movementofanobject’s2-Dshadowcanchangeintoperceptionofa3-DobjectThisisanexampleofstructure-from-motionPerceptualorganizationch858Figure9.4SetupsimilartotheoneusedbyWalla