Home Tekniikka Vaakasuora solu

Vaakasuora solu



Thecellbodyofthehorizontalcellislocatedoutsidetheinnercorelayerandsendsoutmanyhorizontalbranchesextendingintotheoutermeshlayertoformsynapseswithrodcells,bipolarcellsandinterreticularcells.Therearegapjunctionsbetweenadjacenthorizontalcells.

Kaksi vaakasuuntaisten solujen toimintoa:

Oneistoadjustthebrightnessofthevisualsignaloutputbythephotoreceptorcellstoachievevisualbrightnessadaptation

Thesecondistopassthecenter-Peripheralantagonisticreaction,enhancethecontrastoftheedgeoftheimage,highlightthecontourlinesofthescene

Vaakasolujen tiheyskeskialueella on suuri.Incateyes,A-tyypin vaakasolujen tiheyskeskialueella on 225solua/mm2jareuna-alueiden tiheys120solua/mm2.

Horizontalcellscanbedividedintorod-levelcellsthatareonlyincontactwithrodsandcone-levelcellsthatareonlyincontactwithcones.

Kartiohorisonttisolut voidaan jakaa valoisuus (LHC) ja kromaattisuus (CHC).

CHChastwocommonreactiontypes:biphasicreaction,R/Gtypehyperpolarizationforgreenlightanddepolarizationforredlight,depolarizationforgreenlightandhyperpolarityforbluelightModifiedG/Btype;three-phasereaction,hyperpolarizationofredandbluelight,anddepolarizationofgreenlight.

LHCreceivesglutamatergicexcitatorysignalsfromredandgreensensitivecones,andfeedbackinhibitorysignals.AlthoughLHCcontainsGABA,theinteractionofredandgreenconesignalsisnotdeterminedbyGABA.

Intheabsenceoflight,photoreceptorcellsreleaseglutamate,whichdepolarizeshorizontalcells.Depolarizedhorizontalcellswillhyperpolarizeadjacentphotoreceptorcells.Conversely,inalightenvironment,thephotoreceptorcellsreducethereleaseofglutamate,thehorizontalcellsarehyperpolarized,andtheneighboringphotoreceptorcellsaredepolarized.Inthisway,thehorizontalcellsprovidenegativefeedbacktothephotoreceptorcells.

Horizontalcellssummarizethereceivedsignalintensityofphotoreceptorcells,measuretheaveragebrightnessofthelightontheretina,feedbackinhibitionsignaladjuststheoutputsignalofphotoreceptorcellstoanappropriatelevel,sothatthesignalreceivedbybipolarcellsisbothItwillnotbetoosmalltodrowninthenoiseoftheneuralpathway,anditwillnotbetoolargetooversaturatetheneuralpathway.

Theexactmechanismbywhichdepolarizedhorizontalcellshyperpolarizephotoreceptorcellsisparticularlyunknown.AlthoughhorizontalcellscontainGABA,themechanismbywhichhorizontalcellsinhibitconesmaynotinvolvethereleaseofGABAfromhorizontalcellstophotoreceptorcells.

Horizontalcellsandotherretinalinterneuroncellsformexclusiveareasthatareseparatedfromeachother.Thismosaicarrangementprovidesamechanismforevenlydistributingvariousfunctionsub-unitsintheretina,ensuringthatallpartsofthefieldofviewcanreceiveafullsetofvisualprocessing.

Confocalmicrographofmouseretina.Thebluedotsaretheendfeetofconecellsandtheredarehorizontalcells.Thedendritesofthehorizontalcellsarewellconnectedtoeachcone.(Credit:ConfocalmicrographbyPatrickKeeley)

Thecenter-peripheralantagonisticresponseofbipolarcellsisthoughttobeinheritedfromhorizontalcells.Thehorizontalcellsestablishinvaginatedsynapsestowardtheendofthephotoreceptorcells,andthecenter-peripheralantagonisticresponseobviouslyoccursattheendofthecone.

Thehorizontalcellsofthebonyfishformseveralsublayersatthedistaledgeoftheinnernuclearlayeroftheretina.Theouterhorizontalcells(shortaxons)locatedatthemostdistalendformsynapsesonlywiththecones,whilethemiddlehorizontalcellsformsynapses.Cells(withoutaxons)onlyformsynapseswithrods,sotheyareoftencalledconehorizontalcellsandrodhorizontalcells,respectively.

Thestudyofcarpretinafoundthatafteralongperiodofdarkadaptation(2h),thehorizontalcellsoftheconesarestronglysuppressedinresponsetolight,andtheprotrudingendsaresmoothandblunt.Aftertheapplicationofweakbackgroundlight(15min),theresponseofthesecellsincreasedsignificantly,andalargenumberofthorn-shapedstructuresdeepintheinnerconesoftheconesappearedattheirends.Thisthorn-shapedstructureincreasedtheprotrusionsbetweentheconesandthehorizontalcells.Tactiletransmissionefficiencymaybethemorphologicalbasisfortheincreasedlightresponsivenessofcone-levelcells.

ThestudyofcruciancarpretinafoundthatundertheactionofGABA(0.5~5mmol/L),thedarkmembranepotentialofL-conehorizontalcellshyperpolarizedandtheirresponsetolightdecreased.TheeffectofGABAismainlymediatedbytheGABAAreceptorontheendofthecone.However,GABAhasnosignificanteffectonthemembranepotentialandlightresponseoftherod-levelcells.

This article is from the network, does not represent the position of this station. Please indicate the origin of reprint
TOP