Occipital lobe - Wikipedia

The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. ... The primary visual ... Occipitallobe FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Partofthebrainatthebackofthehead Occipitallobe Frontallobe Temporallobe Parietallobe Occipitallobe Lobesofthehumanbrain(theoccipitallobeisshowninred)Medialsurfaceofleftcerebralhemisphere.(cuneusandlingualgyrusareatleft.)DetailsPartofCerebrumArteryPosteriorcerebralarteryIdentifiersLatinLobusoccipitalisMeSHD009778NeuroNames140NeuroLexIDbirnlex_1136TA98A14.1.09.132TA25480FMA67325Anatomicaltermsofneuroanatomy[editonWikidata] Theoccipitallobeisoneofthefourmajorlobesofthecerebralcortexinthebrainofmammals.Thenamederivesfromitspositionatthebackofthehead,fromtheLatinob,"behind,"andcaput,"thehead." Theoccipitallobeisthevisualprocessingcenterofthemammalianbraincontainingmostoftheanatomicalregionofthevisualcortex.[1]TheprimaryvisualcortexisBrodmannarea17,commonlycalledV1(visualone).HumanV1islocatedonthemedialsideoftheoccipitallobewithinthecalcarinesulcus;thefullextentofV1oftencontinuesontotheoccipitalpole.V1isoftenalsocalledstriatecortexbecauseitcanbeidentifiedbyalargestripeofmyelin,theStriaofGennari.VisuallydrivenregionsoutsideV1arecalledextrastriatecortex.Therearemanyextrastriateregions,andthesearespecializedfordifferentvisualtasks,suchasvisuospatialprocessing,colordifferentiation,andmotionperception.Bilaterallesionsoftheoccipitallobecanleadtocorticalblindness(SeeAnton'ssyndrome). Contents 1Structure 2Function 3Clinicalsignificance 3.1Epilepsy 4Additionalimages 5Seealso 6References Structure[edit] Diagramofgyriofbrainviewedonlateralhemisphere.Occipitalgyrishownlowerright Animation.Occipitallobe(red)ofleftcerebralhemisphere. Thetwooccipitallobesarethesmallestoffourpairedlobesinthehumanbrain.Locatedintherearmostportionoftheskull,theoccipitallobesarepartoftheposteriorcerebrum.Thelobesofthebrainarenamedfromtheoverlyingboneandtheoccipitalboneoverliestheoccipitallobes. Thelobesrestonthetentoriumcerebelli,aprocessofduramaterthatseparatesthecerebrumfromthecerebellum.Theyarestructurallyisolatedintheirrespectivecerebralhemispheresbytheseparationofthecerebralfissure.Atthefrontedgeoftheoccipitallobeareseveraloccipitalgyri,whichareseparatedbylateraloccipitalsulcus. Theoccipitalaspectsalongtheinsidefaceofeachhemispherearedividedbythecalcarinesulcus.Abovethemedial,Y-shapedsulcusliesthecuneus,andtheareabelowthesulcusisthelingualgyrus. Damagetotheprimaryvisualareasoftheoccipitallobecancausepartialorcompleteblindness.[2] Function[edit] Theoccipitallobeisdividedintoseveralfunctionalvisualareas.Eachvisualareacontainsafullmapofthevisualworld.Althoughtherearenoanatomicalmarkersdistinguishingtheseareas(exceptfortheprominentstriationsinthestriatecortex),physiologistshaveusedelectroderecordingstodividethecortexintodifferentfunctionalregions. Thefirstfunctionalareaistheprimaryvisualcortex.Itcontainsalow-leveldescriptionofthelocalorientation,spatial-frequencyandcolorpropertieswithinsmallreceptivefields.Primaryvisualcortexprojectstotheoccipitalareasoftheventralstream(visualareaV2andvisualareaV4),andtheoccipitalareasofthedorsalstream—visualareaV3,visualareaMT(V5),andthedorsomedialarea(DM). Theventralstreamisknownforprocessingthe"what"invision,whilethedorsalstreamhandlesthe"where/how."Thisisbecausetheventralstreamprovidesimportantinformationfortheidentificationofstimulithatarestoredinmemory.Withthisinformationinmemory,thedorsalstreamisabletofocusonmotoractionsinresponsetotheoutsidestimuli. Althoughnumerousstudieshaveshownthatthetwosystemsareindependentandstructuredseparatelyfromanother,thereisalsoevidencethatbothareessentialforsuccessfulperception,especiallyasthestimulitakeonmorecomplexforms.Forexample,acasestudyusingfMRIwasdoneonshapeandlocation.Thefirstprocedureconsistedoflocationtasks.Thesecondprocedurewasinalit-roomwhereparticipantswereshownstimulionascreenfor600 ms.Theyfoundthatthetwopathwaysplayaroleinshapeperceptioneventhoughlocationprocessingcontinuestoliewithinthedorsalstream.[3] Thedorsomedial(DM)isnotasthoroughlystudied.However,thereissomeevidencethatsuggeststhatthisstreaminteractswithothervisualareas.AcasestudyonmonkeysrevealedthatinformationfromV1andV2areasmakeuphalftheinputsintheDM.Theremaininginputsarefrommultiplesourcesthathavetodowithanysortofvisualprocessing[4] Asignificantfunctionalaspectoftheoccipitallobeisthatitcontainstheprimaryvisualcortex. Retinalsensorsconveystimulithroughtheoptictractstothelateralgeniculatebodies,whereopticradiationscontinuetothevisualcortex.Eachvisualcortexreceivesrawsensoryinformationfromtheoutsidehalfoftheretinaonthesamesideoftheheadandfromtheinsidehalfoftheretinaontheothersideofthehead.Thecuneus(Brodmann'sarea17)receivesvisualinformationfromthecontralateralsuperiorretinarepresentingtheinferiorvisualfield.Thelingulareceivesinformationfromthecontralateralinferiorretinarepresentingthesuperiorvisualfield.Theretinalinputspassthrougha"waystation"inthelateralgeniculatenucleusofthethalamusbeforeprojectingtothecortex.Cellsontheposterioraspectoftheoccipitallobes'graymatterarearrangedasaspatialmapoftheretinalfield.Functionalneuroimagingrevealssimilarpatternsofresponseincorticaltissueofthelobeswhentheretinalfieldsareexposedtoastrongpattern. Clinicalsignificance[edit] Ifoneoccipitallobeisdamaged,theresultcanbehomonymoushemianopsiavisionlossfromsimilarlypositioned"fieldcuts"ineacheye.Occipitallesionscancausevisualhallucinations.Lesionsintheparietal-temporal-occipitalassociationareaareassociatedwithcoloragnosia,movementagnosia,andagraphia.Damagetotheprimaryvisualcortex,whichislocatedonthesurfaceoftheposterioroccipitallobe,cancauseblindnessduetotheholesinthevisualmaponthesurfaceofthevisualcortexthatresultedfromthelesions.[5] Epilepsy[edit] Recentstudieshaveshownthatspecificneurologicalfindingshaveaffectedidiopathicoccipitallobeepilepsies.[6]Occipitallobeseizuresaretriggeredbyaflash,oravisualimagethatcontainsmultiplecolors.Thesearecalledflickerstimulation(usuallythroughTV)theseseizuresarereferredtoasphoto-sensitivityseizures.Patientshavingexperiencedoccipitalseizuresdescribedtheirseizuresasfeaturingbrightcolors,andseverelyblurringtheirvision(vomitingwasalsoapparentinsomepatients).Occipitalseizuresaretriggeredmainlyduringtheday,throughtelevision,videogamesoranyflickerstimulatorysystem.[7]Occipitalseizuresoriginatefromanepilepticfocusconfinedwithintheoccipitallobes.Theymaybespontaneousortriggeredbyexternalvisualstimuli.Occipitallobeepilepsiesareetiologicallyidiopathic,symptomatic,orcryptogenic.[8]Symptomaticoccipitalseizurescanstartatanyage,aswellasanystageafterorduringthecourseoftheunderlyingcausativedisorder.Idiopathicoccipitalepilepsyusuallystartsinchildhood.[8]Occipitalepilepsiesaccountforapproximately5%to10%ofallepilepsies.[8] Additionalimages[edit] Baseofbrain. Drawingtoillustratetherelationsofthebraintotheskull. Occipitallobeinblue Occipitallobe Occipitallobe Ventriclesofbrainandbasalganglia.Superiorview.Horizontalsection.Deepdissection Seealso[edit] Medicalportal Thisarticleusesanatomicalterminology. Alphawave Lobesofthebrain Regionsofthehumanbrain SulcusLunatus Visualevokedpotential Verticaloccipitalfasciculus VisualSnow References[edit] WikimediaCommonshasmediarelatedtoOccipitallobe. ^"SparkNotes:BrainAnatomy:ParietalandOccipitalLobes".Archivedfromtheoriginalon31December2007.Retrieved27February2008. ^Schacter,D.L.,Gilbert,D.L.&Wegner,D.M.(2009).Psychology.(2nded.).NewWork(NY):WorthPublishers. ^(Valyear,Culham,Sharif,Westwood,&Goodale,2006). ^(Valyearetal.,2006). ^Carlson,NeilR.(2007).Psychology :thescienceofbehaviour.NewJersey,USA:PearsonEducation.pp. 115.ISBN 978-0-205-64524-4. ^Chilosi,AnnaMaria;Brovedani(November2006)."NeuropsychologicalFindingsinIdiopathicOccipitalLobeEpilepsies".Epilepsia.47(s2):76–78.doi:10.1111/j.1528-1167.2006.00696.x.PMID 17105468.S2CID 23702191. ^DestinaYalçin,A.;Kaymaz,A.;Forta,H.(2000)."Reflexoccipitallobeepilepsy".Seizure.9(6):436–441.doi:10.1053/seiz.2000.0424.PMID 10986003. ^abcAdcock,JaneE;Panayiotopoulos,ChrysostomosP(31October2012)."JournalofClinicalNeurophysiology".OccipitalLobeSeizuresandEpilepsies.29(5):397–407.doi:10.1097/wnp.0b013e31826c98fe.PMID 23027097. vteAnatomyofthecerebralcortexofthehumanbrainFrontallobeSuperolateralPrefrontal Superiorfrontalgyrus 4 6 8 Middlefrontalgyrus 9 10 46 Inferiorfrontalgyrus:11 47-Parsorbitalis Broca'sarea 44-Parsopercularis 45-Parstriangularis Superiorfrontalsulcus Inferiorfrontalsulcus Precentral Precentralgyrus Precentralsulcus Medial/inferiorPrefrontal Superiorfrontalgyrus 4 6 Medialfrontalgyrus 8 9 Paraterminalgyrus/Paraolfactoryarea 12 Straightgyrus 11 Orbitalgyri/Orbitofrontalcortex 10 11 12 Ventromedialprefrontalcortex 10 Subcallosalarea 25 Olfactorysulcus Orbitalsulcus Precentral Paracentrallobule 4 Paracentralsulcus Both Primarymotorcortex 4 Premotorcortex 6 Supplementarymotorarea 6 Supplementaryeyefield 6 Frontaleyefields 8 ParietallobeSuperolateral Superiorparietallobule 5 7 Inferiorparietallobule 40-Supramarginalgyrus 39-Angulargyrus Parietaloperculum 43 Intraparietalsulcus Medial/inferior Paracentrallobule 1 2 3 5 Precuneus 7 Marginalsulcus Both Postcentralgyrus/Primarysomatosensorycortex 3,1and2 Secondarysomatosensorycortex 5 Posteriorparietalcortex 7 OccipitallobeSuperolateral Occipitalpoleofcerebrum Occipitalgyri Lateraloccipitalgyrus 18 19 Lunatesulcus Transverseoccipitalsulcus Medial/inferior Visualcortex 17 Cuneus Lingualgyrus Calcarinesulcus TemporallobeSuperolateral Transversetemporalgyrus/Auditorycortex 41and42 Superiortemporalgyrus 38 22/Wernicke'sarea(Planumtemporale) Superiortemporalsulcus Middletemporalgyrus 21 Medial/inferior Occipitotemporalsulcus Fusiformgyrus 37 Medialtemporallobe 27 28 34 35 36 Inferiortemporalsulcus Inferiortemporalgyrus 20 Interlobarsulci/fissuresSuperolateral Central(frontal+parietal) Lateral(frontal+parietal+temporal) Parieto-occipital Preoccipitalnotch Medial/inferior Longitudinalfissure Cingulate(frontal+cingulate) Collateral(temporal+occipital) Callosalsulcus LimbiclobeParahippocampalgyrus anterior Entorhinalcortex Perirhinalcortex Postrhinalcortex Posteriorparahippocampalgyrus Prepyriformarea Cingulatecortex/gyrus Subgenualarea 25 Anteriorcingulate 24 32 33 Posteriorcingulate 23 31 Isthmusofcingulategyrus:Retrosplenialcortex 26 29 30 Hippocampalformation Hippocampalsulcus Fimbriaofhippocampus Dentategyrus Rhinalsulcus Other Indusiumgriseum Uncus Amygdala Insularcortex Insularcortex General Operculum Polesofcerebralhemispheres Somecategorizationsareapproximations,andsomeBrodmannareasspangyri. 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