Introduction
Ganglioncelllayer:Locatedintheinnermostlayeroftheretina,itiscomposedofmultipolarganglioncells.Itsdendritesaremainlyconnectedwithbipolarcellsandcanalsopassthroughapodocytes.Lateralconnection;itsaxonsextendtotheopticnerveheadandpassthroughthelaminatoformtheopticnerve.
Transmittingsignals
Thereareseveraldifferenttypesofganglioncellsthattransmitbrightnesssignals,andtheyareexcitedbybipolarcells,horizontalcells,andapodocytesindifferentsituations.Asmallnumberofganglioncellsmainlyrespondtotheintensity(brightness)ofthelightthathitsthephotoreceptors.Aslongasthebrightnessishigh,thefrequencyofimpulsesfromthesecellsisalwayshigherthanthenaturalfrequencyoffiringimpulses.Itisthesignalsemittedbythesecellsthatletthebrainknowthetotalbrightnessofthesceneitsees.
Transmitthesignalaboutthecontrastinthevisualscene-intheprocessoflateralinhibition,mostganglioncellshardlyrespondtotheactuallevelofbrightnessinthescene,butonlyreacttotheedgeofthecontrastinthescene.Becausethisisthemainwaytheformofthesceneistransmittedtothebrain,thefollowingexplainshowthisprocessoccurs.
Whenuniformlighthitstheentireretina(thatis,whenallphotoreceptorsareequallyexcitedbytheincidentlight),thecontrasttypeganglioncellsareneitherexcitednorinhibited.Thisisbecausethesignalstransmitteddirectlyfromthephotoreceptorsthroughthebipolarcellsareexcitatory,whilethesignalstransmittedfromthesurroundingphotoreceptorsthroughthehorizontalcellsareinhibited.Thesetworeactionsoffseteachother.Onthecontrary,ifthereisacontrastedge,thephotoreceptorsononesideoftheedgeareexcited,andthephotoreceptorsontheothersideoftheedgearenotexcited,thereisnodirectoffsetbytheexcitatorysignalofthebipolarcellandthehorizontalcellinhibitorysignal.Theresultisthattheganglioncellsonthebrightsideareexcited,whilethedarksideissuppressed.
Thebalanceprocessoftheexcitatorysignalandtheinhibitorysignalisexactlythesameasthelateralinhibitionduringthetransmissionofvariousothersensorysignals.Thisprocessisamechanismusedbythenervoussystemtoenhancecontrast.
Vastaanottokenttä
Kaksi tyyppiä gangliosoluja: ON-keskitetty tyyppi, OFF-keskitetty tyyppi
PÄÄLLÄ-keskitetty tyyppi
Kun valopisteet ovatvastaanottokentänkeskipisteessä, tämän ganglionsolun laukeaminen äkillisesti lisääntyy. (Jaettu alue on ympyrä, jonka katselukentän keskipiste on pisteenä.Tätä aluetta kutsutaan alueeksi); Jos valopisteet putoavat kokonaan toiselle alueelle, taustasäteily loppuu kokonaan. Tätä kutsutaan OFF-alueeksi. Tästä näkökulmasta katsottuna ON-keskittyneet solut ovat"valoa antavaan tyyppiin" [ON])".ON-keskitetyissä ganglionsoluissa valoenergia putoaa(antava)intheONareaisSee,valoputoava(antava)OFF-alueella ei ole näkyvissä.
OFF-centeredtype
Whenthelightspotisremovedfromthecenterofthereceptivefield,itwillemitstrongly.(ThesmallcircularareaemittedistheONarea).Onthecontrary,ifthelightisinthecenterofthefieldofview,itstopsemitting.Outsidethissmallcentralcirculararea,thereisanannularrangearoundthem.Inthisring-shapedarea,ifthesmalllightspotisremoved,thedistributionwillstop.ThisareaiscalledtheOFFarea.Fromthispointofview,OFF-centeredcellsbelongtothe“light-extractedtype(thelightspotinthecenterofthefieldofviewisremovedtoproduceemission,andthelightwillstopemitting[OFF])".ForOFF-centeredganglioncells,ThelightevacuatedintheONareacanbeseen,andthelightevacuatedintheOFFareaisinvisible.Inthesameway,thelightfallingintheONareaisinvisible,andthelightfallingintheOFFareacanbeseen.
Visualreceptivefieldreferstoacertainareaorrangeontheomentum.Whenitisstimulated,itcanactivatetheactivityoftheinterlayernervecellsthatareconnectedtothevisualsystemandthisarea.Thisareaontheomentumisthereceptivefieldofthesenervecells.Thereceptivefieldofaganglioncellisonlyintheareaconnectedtoitontheretina.Towhatextentanervenodeisconnectedtotheretina,thelargestreceptivefieldisthesize.