Dhau Muaj coob tus Neurons lwj lub cim xeeb

Too Many Neurons Spoil the Memory

Kev tshawb fawb tshiab qhia cov cellular mechanisms uas nco-encoding neuronal tes hauj lwm mam li


Powered by Guardian.co.ukQhov tsab xov xwm hu ua “Ntau neurons lwj lub cim xeeb” raug sau los ntawm Mo Costandi, rau theguardian.com rau hnub Friday 12 Lub ob hlis ntuj 2016 15.15 UTC

Qhia rau kuv nyob qhov twg nyob rau hauv lub xav, tsis nco qab lawm txog koj hu lawv tawm? Qhia rau kuv nyob qhov twg nyob rau hauv lub yeej ntawm cov laus, thiab qhov uas cov ancient hlub, Thiab thaum lawv yuav txuas hnub nyoog dua, thiab lub hmo ntuj ntawm oblivion yav dhau los, Xwv kom kuv yuav traverse lub sij hawm thiab qhov chaw deb thaj chaw deb, thiab coj zoo rau hauv ib lub tam sim no tu siab thiab ib hmo ntawm qhov mob? Qhov twg tawm mus ncig koj, O thought? Yuav ua li cas tej thaj chaw deb av yog koj ya davhlau? Yog hais tias koj returnest mus rau lub caij tam sim no ntawm kev txom nyem, Koj puas xav kom koj coj comforts ntawm koj tis, thiab lwg thiab zib ntab thiab tshuaj, Los yog tshuaj lom los ntawm lub suab puam wilds, los ntawm lub qhov muag ntawm tus envier?

Nyob rau hauv nws epic paj huam, Visions ntawm lub Ntxhais Albion, William Blake xav txog qhov xwm ntawm lub cim xeeb, nws muaj peev xwm puas thauj peb mus nyob deb lub sij hawm thiab qhov chaw, thiab cov haib cwj pwm txawv, ob zoo thiab tsis zoo, hais tias peb cov recollections yuav evoke. Cov paj huam muaj cov lus nug uas nyob twj ywm mas ev hnub no, xws li dab tsi tshwm sim rau peb ntev-poob puas, thiab ua li cas peb muab rau lawv?

Ntau tshaj ob centuries tom qab, lub mechanisms ntawm lub cim xeeb cia thiab nqi yog cov feem ntau sib kawm phenomena nyob rau hauv lub hlwb sciences. Nws yog lug ntseeg tias nco tsim yuav lub strengthening ntawm kev sib txuas ntawm sparsely faib tes hauj lwm ntawm neurons nyob rau hauv ib lub paj hlwb qauv hu ua lub hippocampus, thiab hais tias tom ntej nqi yuav reactivation ntawm tib neuronal lossis. thiab tsis tau, neuroscientists tseem nyuaj rau teb Blake lus nug twv yuav raug hu.

Tam sim no, ib pab neeg ntawm soj ntsuam nyob rau hauv lub University of Geneva tau ua lwm tseem ceeb ua ntej nyob rau hauv peb to taub txog cov neural mechanisms lwm nco tsim. Siv ib lub xeev-of-the-art txoj kev hu ua optogenetics, lawv qhia li cas rau cov neuronal lossis uas encode puas mam li, pom hais tias lossis muaj ntau dhau lawm neurons - los yog ib yam nkaus thiab ob peb - ​​tsis nco nqi.

optogenetics yog ib tug tsis tshua muaj hwj chim loj cov txheej txheem uas yuav qhia algal cov nqaijrog hu ua channelrhodopsins (ChRs) mus rau hauv neurons. Qhov no renders lub hlwb rhiab mus rau lub teeb, xws li hais tias txog qee pab pawg ntawm lawv muaj peev xwm yuav hloov los yog tua, siv pulses ntawm laser lub teeb tauj mus rau hauv lub hlwb ntawm kho qhov muag fibers, rau ib tug timescale ntawm milliseconds.

Nyob rau hauv xyoo tsis ntev los, soj ntsuam tau siv optogenetics rau daim ntawv lo hippocampal neurons uas ua active thaum lub sij hawm nco tsim nyob rau hauv lub nas hlwb, thiab muab cov uas sau tias lossis nyob rau hauv ntau txoj kev. Nyob rau hauv no txoj kev, lawv yuav leg ntaubntawv tib lossis mus induce nco nqi; hloov ntshai puas tau rau los yog tawm; hloov tsis zoo puas rau hauv zoo sawv daws yuav, los yog vice versa; thiab txawm cog nkaus cuav puas mus rau hauv lub hlwb ntawm nas.

Cov kev tshawb fawb tshiab, coj los ntawm Pablo Mendez thiab lub caij Dominique Muller, uas tragically tuag nyob rau hauv ib tug gliding kev huam yuaj nyob rau hauv lub Plaub Hlis ntawm xyoo tas los, ua nyob rau hauv no ua ntej lawm ua hauj lwm. Lawv tsim txhob kaw engineered nas hais ChR nyob rau hauv granule hlwb nyob rau ib sab ntawm lub paj hlwb, nyob rau hauv lub dentate cheeb tsam ntawm lub hippocampus. Cov tshuab granule hlwb yog lub hauv paus ntsiab neurons nyob rau hauv no cheeb tsam ntawm lub hippocampus, uas yog xav kom tau ib qho tseem ceeb rau hippocampal zog xws li nco thiab spatial navigation. Lawv muab tso rau cov tsiaj mus rau hauv loj tawb, uas ib co ntawm lawv mus tshawb lawv cov tshiab ib puag ncig. Meanwhile, lawv optogenetically tshuab txais random granule hlwb nyob rau hauv ib co ntawm cov nas, tab sis tsis lwm tus.

Hippocampal granule hlwb hnov ​​txog Channelrhodopsin (nyob rau hauv liab).
Hippocampal granule hlwb hnov ​​txog Channelrhodopsin (nyob rau hauv liab). duab: Pablo Mendez

Thaum lawv dissected thiab nais maum kuaj cov tsiaj cov hlwb 45 feeb tom qab, kev soj ntsuam pom spatial kev tshawb kawm evoked ua si nyob rau hauv lossis ntawm hippocampal neurons, raws li txiav txim los ntawm theem ntawm cov cFos, ib tug thiaj li hu ua 'tam sim ntawd thaum ntxov' noob uas yog switched sai sai thaum neurons pib rau hluav taws. ceeb, nas tso cai los mus tshawb nrhiav lawv lub tawb tau ntau dua tus xov tooj ntawm cFos-hais granule hlwb tshaj cov neeg tshuav nyob rau hauv lawv lub tsev tawb rau lub caij ntawm qhov xyaum ua tej, thiab cov neeg uas tau txais optogenetic stimulation thaum lub sij hawm qhov kev tshawb kawm tau ho ntau dua tus xov tooj ntawm cFos-positive neurons dua cov uas tsis tau.

Qhov no qhia tau tias spatial kev tshawb kawm evokes ua si nyob rau hauv lossis ntawm dentate granule hlwb, thiab hais tias cia li Process cov kev ua ntawm cov tes hauj lwm nrog optogenetic stimulation tsub kom qhov luaj li cas ntawm cov lossis, los yog tus xov tooj ntawm lub hlwb nyob rau hauv lawv.

Tab sis manipulating qhov loj ntawm lub lossis muaj tej nyhuv rau tus cwj pwm? Yog xav paub, Mendez thiab nws cov npoj yaig muab tso nas hais ChR nyob rau hauv lawv cov hippocampi mus rau lwm lub tawb, thiab muab lawv ob peb me me hluav taws xob shocks. Nrog repetition ntawm qhov kev kho no, tus nas sai sai kawm ntshai lub tawb, thiab sai sai khov txog thaum rov qab mus rau hauv nws, txawm tias thaum lawv tsis muab ntau shocks.

Qhov no lub sij hawm, kev soj ntsuam optogenetically tsa random granule hlwb nyob rau hauv ib co ntawm cov nas, tab sis tsis lwm tus, thaum lub sij hawm qhov kev cob, nyob rau hauv thiaj li yuav nce qhov loj ntawm lub neuronal khaub ncaws ntau uas encodes lub fearful nco. Cov nas tshaaj tsawg khov cwj pwm thaum rov qab mus rau tib lub tawb tshaj lwm cov neeg uas tau txais tsis muaj stimulation. Tab sis lub stimulation kuj tsim dag ntshai puas, xws li hais tias cov tsiaj froze nyob rau hauv lwm yam xwm txheej, heev.

Inhibition ntawm random granule hlwb muaj cov nyhuv tib yam, tawm tswv yim tias yuav luag kev Process lub xov tooj ntawm neurons nyob rau hauv cov khaub ncaws ntau cuam tshuam nrog cov tsiaj cov muaj peev xwm yuav tau nco qab lub fearful puas. Cov kev tshawb nrhiav yog muaj raws li cov neeg ntawm ib tug ua ntej lawm kev tshawb, uas kuj pom tias inhibiting los yog stimulating granule cell ua si impairs contextual kawm.

Yuav kom to taub yog vim li cas qhov no tej zaum yuav, kev soj ntsuam ua ib series ntawm thwmsim, siv microelectrodes los sau cov kev ua ntawm neurons nyob rau hauv slices ntawm hippocampal cov ntaub so ntswg. Cov kev qhia tias optogenetic stimulation ntawm granule hlwb ua ib tug robust teb nyob rau hauv nyob sib ze interneurons, uas tso cov inhibitory neurotransmitter GABA.

Yog li, lub firing ntawm granule hlwb ua inhibitory interneurons, uas dampen uas nyob ib sab granule hlwb thiab tiv thaiv kom txhob rau lawv los ntawm kev nkag mus kawm cov khaub ncaws ntau. Nyob rau hauv no txoj kev, interneurons tshwm sim mus rau stabilize tshiab khiv-tsim puas los ntawm regulating tus naj npawb thiab muab faib rau granule hlwb muab kev koom tes nyob rau hauv encoding puas. Activating los yog silencing random granule hlwb ntshai tus txheej txheem no thiab alters tus xov tooj ntawm granule hlwb, uas tej zaum yuav ua rau cov tshiab puas tsis ruaj tsis khov.

"Nyob rau hauv txoj kev tshawb no, peb siv ib tug yooj yim hauv daim ntawv ntawm lub cim xeeb, lub cim xeeb ntawm ib tug spatial ntsiab lus teb, tab sis cov kev sib tw yog kev kawm yuav ua li cas ntau yaam puab paub yog cim, thiab yuav ua li cas lub hlwb tseem ua hauj lwm nrog cov cia ntawm ntau yaam puab paub,"Hais tias Mendez. "To taub cov lus nug no yuav pab kom peb to taub txog cov kev txwv ntawm lub paj hlwb cia muaj peev xwm."

reference

Stefanelli, T., et al. (2016). Hippocampal Somatostatin Interneurons Control lub Loj ntawm Neuronal nco lossis. neuron, 89: 1-12. DOI: 10.1016/j.neuron.2016.01.024 [Abstract]

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