Ithiyori entsha yokwakheka kwe-synapse kwingqondo
Ukuhlengahlengiswa kwakhona kwi-cortex ebonakalayo: ngaphambi (ngasekhohlo) kwaye emva nje komonakalo kwi-retina (embindini), nakwisigaba esilandelayo (ekunene). Uninzi lwee-neuron kwindawo apho imifanekiso iqikelelwa kwi-retina eyonakeleyo inokufezekisa imvelaphi yayo…Kaninzi
Ubuchopho bomntu buhlala buguquka kubo bonke ubomi bomntu. Uqhagamshelo olutsha lusoloko luyilwa ngelixa iisynapse ezingasasetyenziswayo ziwohloka. Ukuza kuthi ga ngoku, kuncinci okwaziwayo malunga neendlela ezisemva kwezi nkqubo. U-Jülich neuroinformatician uGqr Markus Butz ngoku uye wakwazi ukuchaza ukubunjwa kothungelwano olutsha lwe-neural kwi-cortex ebonakalayo kumgaqo olula we-homeostatic osisiseko sezinye iinkqubo ezininzi zokuzilawula kwindalo. Ngale ngcaciso, yena kunye nogxa wakhe uDkt Arjen van Ooyen wase-Amsterdam baphinde banikeze ithiyori entsha malunga neplastiki yengqondo - kunye nendlela entsha yokuqonda iinkqubo zokufunda kunye nokunyanga ukulimala kwengqondo kunye nezifo.
Ubuchopho babantu abadala abukho zintambo kwaphela. Iingcali zenzululwazi ziye zaqinisekisa ngokuphindaphindiweyo le nyaniso kwiminyaka embalwa edlulileyo ngokusebenzisa iindlela ezahlukeneyo zokucinga. Oku kubizwa ngokuba yi-neuroplasticity ayidlali indima ephambili kuphela kwiinkqubo zokufunda, ikwabangela ukuba ingqondo ikwazi ukuchacha kukwenzakala kwaye ihlawule ukulahleka kwemisebenzi. Abaphandi basanda kufumanisa ukuba nakwingqondo yabantu abadala, kungekhona nje kuphela ukuba i-synapses ekhoyo ivumelane neemeko ezintsha, kodwa unxibelelwano olutsha luhlala lwenziwa kwaye luhlengahlengiswe. Nangona kunjalo, bekungekaziwa ukuba ezi nkqubo zohlengahlengiso lwendalo zilawulwa njani kwingqondo. Kwijenali yofikelelo oluvulelekileyo PLOS iComputerational Biology, Butz kunye novan Ooyen ngoku babonisa umgaqo olula ochaza indlela ezi intanethi ezintsha ze-neurons zenziwe ngayo.
"Kusenokwenzeka ukuba iplastikhi yengqondo isisiseko sokwakhiwa kwememori yexesha elide," utshilo uMarkus Butz, obesebenza kwi-Simulation Laboratory Neuroscience esandul' ukusekwa kwiziko le-Jülich Supercomputing kwezi nyanga zimbalwa zidlulileyo. “Kwaye ayikokufunda kuphela. Ukulandela ukunqunyulwa kwemilenze, ukwenzakala kwengqondo, ukuqala kwezifo ze-neurodeergenerative, kunye nemivimbo, amanani amakhulu ee-synapses amatsha aye aqulunqwa ukuze alungelelanise ingqondo notshintsho oluhlala luhleli kwiipatheni zempembelelo ezingenayo. ”
Umsebenzi ulawula ukwakheka kwe-synapse
Ezi ziphumo zibonisa ukuba ukubunjwa kwee-synapses ezintsha kuqhutywa kukuthambekela kwee-neurons ukugcina inqanaba lomsebenzi wombane 'olusetwe kwangaphambili'. Ukuba umyinge womsebenzi wombane uwela ngaphantsi komda othile, i-neurons iqala ukwakha ngokusebenzayo amanqaku amatsha oqhagamshelwano. Ezi zisisiseko se-synapses entsha ehambisa igalelo elongezelelweyo - izinga lokudubula kwe-neuron liyenyuka. Oku kusebenza kwakhona ngenye indlela: ngokukhawuleza ukuba inqanaba lomsebenzi lidlula umda ophezulu, inani lokuxhunyelelwa kwe-synaptic liyancitshiswa ukukhusela nayiphi na i-overexcitation - i-neuron firing rate iwa. Iifom ezifanayo ze-homeostasis zihlala zivela kwindalo, umzekelo kulawulo lobushushu bomzimba kunye namanqanaba eswekile yegazi.
Noko ke, uMarkus Butz ugxininisa ukuba oku akusebenzi ngaphandle kovuselelo oluthile oluncinane lwemithambo-luvo: “Ineuron engasafumani naluphi na uvuselelo ilahlekelwa nangakumbi ziisynapses kwaye iya kufa emva kwexesha elithile. Kuya kufuneka siwuthathele ingqalelo lo mqobo ukuba sifuna ukuba iziphumo zokulinganisa kwethu zivumelane nokuqwalaselwayo. ” Ukusebenzisa i icortex ebonakalayo njengomzekelo, iingcali ze-neuroscientists ziye zafunda imigaqo ngokubhekiselele kwi-neuron ezenza uxhulumaniso olutsha kwaye zilahle ii-synapse ezikhoyo. Kulo mmandla wobuchopho, malunga ne-10% ye leesynapse zihlaziywa rhoqo. Xa i-retina yonakele, le pesenti iyanda ngakumbi. Ukusebenzisa ukulinganisa kwekhompyutheni, ababhali baphumelele ekuqulunqweni ngokutsha kwe-neurons ngendlela ehambelana neziphumo zovavanyo ezivela kwi-cortex ebonakalayo yeegundane kunye neenkawu ezinee-retinas ezonakalisiweyo.
I-visual cortex ifaneleke ngokukodwa ukubonisa umgaqo omtsha wokukhula, kuba inepropathi ekubhekiselwa kuyo njenge-retinotopy: Oku kuthetha ukuba amanqaku aqikelelwa ecaleni kwelinye kwi-retina nawo acwangciswa ecaleni kwelinye xa eqikelelwa kwi-cortex ebonakalayo, nje. njengakwimephu. Ukuba iindawo ze-retina zonakele, iiseli apho imifanekiso ehambelana nayo iqikelelwa zifumana amagalelo ahlukeneyo. "Kwimizekelo yethu, unokubona ukuba iindawo ezingasafumani galelo kwi-retina ziqala ukwakha ii-crosslinks, ezibavumela ukuba bafumane imiqondiso emininzi kwiiseli ezingabamelwane," utshilo uMarkus Butz. Ezi crosslinks zenziwe ngokucothayo ukusuka kwincam yendawo eyonakeleyo ukuya embindini, kwinkqubo efana nokuphiliswa kwenxeba, de inqanaba lokuqala lomsebenzi libuyiselwe ngaphezulu okanye ngaphantsi.
Iplastiki yeSynaptic kunye nesakhiwo
"Umgaqo omtsha wokukhula ubonelela ngeplastiki yesakhiwo kunye nomgaqo ophantse ube lula njengalowo we-synaptic plasticity," kusho umbhali-mbhali u-Arjen van Ooyen, oye wasebenza kwiimodeli zokuphuhliswa kwe-neural networks amashumi eminyaka. Kwangowe-1949, unjingalwazi wezengqondo uDonald Olding Hebb wafumanisa ukuba unxibelelwano phakathi neurons ezisebenza rhoqo ziyakomelela. Abo batshintshiselana ngolwazi oluncinci baya kuba buthathaka. Namhlanje, izazinzulu ezininzi zikholelwa ukuba lo mgaqo we-Hebbian udlala indima ephambili kwiinkqubo zokufunda kunye nememori. Ngelixa iplastiki ye-synaptic ekubandakanyekeni ngokukodwa kwiinkqubo zexesha elifutshane ezithatha ukusuka kwii-milliseconds ezimbalwa ukuya kwiiyure ezininzi, i-plasticity yesakhiwo yandisa izikali zexesha elide, ukusuka kwiintsuku ezimbalwa ukuya kwiinyanga.
Iplastiki yesakhiwo ngoko idlala indima ebaluleke kakhulu ngexesha (ekuqaleni) kwesigaba sokubuyisela izigulane ezichatshazelwa zizifo ze-neurological, ezihlala iiveki kunye neenyanga. Umbono oqhuba le projekthi kukuba iingcamango ezixabisekileyo zonyango lwezigulane ze-stroke zingabangela ukuqikelelwa okuchanekileyo kokubunjwa kwe-synapse. Ukuba oogqirha bebesazi ukuba ubume bobuchopho besigulana buya kutshintsha njani kwaye bulungelelaniswe kwakhona ngexesha lonyango, banokumisela amaxesha afanelekileyo ezigaba zokuvuselela kunye nokuphumla, ngaloo ndlela bephucula ukusebenza kakuhle konyango.
Indlela entsha yezicelo ezininzi
Ngaphambili kwakucingelwa ukuba iplastiki yesakhiwo nayo ilandela umgaqo weplastiki ye-Hebbian. Iziphumo zibonisa ukuba iplastiki yesakhiwo ilawulwa ngumgaqo we-homeostatic endaweni yoko, engazange ithathelwe ingqalelo ngaphambili, "kusho uProf Abigail Morrison, intloko yeSimulation Laboratory Neuroscience eJülich. Iqela lakhe sele lidibanisa umgaqo omtsha kwisoftware yokulinganisa efumaneka ngokukhululekileyo iNEST, esetyenziswa zizazinzulu ezininzi kwihlabathi liphela.
Ezi ziphumo zikwabalulekile kwiProjekthi yoBuchule boMntu. Iingcali ze-Neuroscientists, izazinzulu zonyango, izazinzulu zekhompyuter, iingcali zefiziksi, kunye neengcali zezibalo eYurophu zisebenza ngesandla ukulinganisa ingqondo yomntu yonke kwiikhompyuter ezisebenza kakhulu zesizukulwana esilandelayo ukuze uqonde ngcono indlela esebenza ngayo. “Ngenxa yobunzima bokujikeleza kwe-synaptic emntwini ngengqondo, Akunakwenzeka ukuba ukunyamezela kwayo kunye nokuguquguquka kufezekiswa ngokusekelwe kwimithetho yoxhumo olumileyo. Iimodeli ke ngoko ziyafuneka kwinkqubo yokuzilungiselela,” utsho uProf Markus Diesmann ovela kwiJülich's Institute of Neuroscience and Medicine, obandakanyekayo kule projekthi. Uphethe i-Computational and Systems Neuroscience (INM-6), i-substitute esebenza kwi-interface phakathi kophando lwe-neuroscientific kunye ne-teknoloji yokulinganisa.
Hlola kwakhona: Ukufunda kwakhona indlela yokubona: Abaphandi bafumana utshintsho olubalulekileyo ekucinyweni kuphuhliso lokubonwayo
Iinkcukacha ezithe xaxe: Umgaqo olula we-dendritic spine kunye nokwakheka kwe-axonal bouton unokuphendula ngohlengahlengiso lwe-cortical emva kwezilonda ezigxilwe kwi-retinal, uMarkus Butz, u-Arjen van Ooyen, I-PloS Comput Biol (yapapashwa kwi-intanethi nge-10 ka-Oktobha 2013); I-DOI: 10.1371/journal.pcbi.1003259
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