Vision-ManhattanvilleCollege视觉-曼哈顿维尔学院

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1、ChapterSixVisionVisualCodingandRetinalReceptorsReception-absorptionofphysicalenergybyreceptorsTransduction-theconversionofphysicalenergytoanelectrochemicalpatternintheneuronsCoding-one-to-onecorrespondencebetweensomeaspectofthephysicalstimulusandsomeaspectofthenervoussystemactivityVisualCodingand

2、RetinalReceptorsFromNeuronalActivitytoPerceptioncodingofvisualinformationinthebraindoesnotduplicatethestimulusbeingviewedGeneralPrinciplesofSensoryCodingMullerandthelawofspecificenergies-anyactivitybyaparticularnervealwaysconveysthesamekindofinformationtothebrainQualificationsoftheLawofSpecificEn

3、ergiestherateoffiringorpatternoffiringmaysignalindependentstimulitimingofactionpotentialsmaysignalimportantinformationindicatingsuchthingsasmovementthemeaningofoneneurondependsonwhatotherneuronsareactiveatthesametimeVisualCodingandRetinalReceptorsTheEyeandItsConnectionstotheBrainPupil-openinginth

4、ecenteroftheeyethatallowslighttopassthroughLens-focusesthelightontheretinaRetina-backsurfaceoftheeyethatcontainsthephotoreceptorsTheFovea-pointofcentralfocusontheretinaTheRouteWithintheRetinaphotoreceptors-rodsandconesbipolarcells-receiveinputfromrodsandconesganglioncells-receiveinputfrombipolarc

5、ellsopticnerve-madeupofaxonsofganglioncellsblindspot-thepointwheretheopticnerveleavestheeyeFigure6.2  CrosssectionofthevertebrateeyeNotehowanobjectinthevisualfieldproducesaninvertedimageontheretina.Figure6.4  VisualpathwithintheeyeballThereceptorssendtheirmessagestobipolarandhorizontalcells,which

6、inturnsendmessagestotheamacrineandganglioncells.Theaxonsoftheganglioncellslooptogethertoexittheeyeattheblindspot.Theyformtheopticnerve,whichcontinuestothebrain.AnimationFigure6.6  TwodemonstrationsoftheblindspotoftheretinaCloseyourlefteyeandfocusyourrighteyeontheointhetoppart.Movethepagetowardyou

7、andaway,noticingwhathappenstothex.Atadistanceofabout25cm(10inches),thexdisappears.Nowrepeatthisprocedurewiththebottompart.Atthatsamedistancewhatdoyousee?VisualReceptors:RodsandConesRodsabundantintheperipheryoftheretina