Neurons ntau lwj tus nco

Too Many Neurons Spoil the Memory

Kev tshawb fawb tshiab reveals cellular mechanisms uas cim xeeb-encoding neuronal tes hauj lwm mam li tawm


Powered by Guardian.co.ukNo tsab xov xwm hu “Neurons ntau lwj tus nco” yog sau los ntawm Mo Costandi, kev theguardian.com txog hnub Friday 12th lub ob hlis ntuj 2016 15.15 UTC

Qhia rau kuv qhov chaw nyob tus xav, tsis nco qab lawm kom thou hu lawv yees? Qhia rau kuv qhov chaw nyob lub yeej no tsawv old, thiab qhov twg lub ancient hlub, Thiab thaum yuav lawv txuas hnub nyoog dua, thiab hmo dhau los oblivion, Tias kuv traverse zaug thiab tej lub tej thaj chaw deb deb, thiab nqa Comforts ib tam sim no tu siab heev thiab mob ib hmo? Qhov twg goest thou, O xav? Rau dab teb tej thaj chaw deb yog thy ya davhlau? Yog thou returnest rau lub caij tam sim no ntawm affliction, Wilt thou nqa comforts rau thy tis, lwg thiab koj niam thiab tej tshuaj, Los yog cov tshuaj phiv los ntawm tus wilds suab puam, ntawm lub qhov muag ntawm tus envier?

Nyob rau hauv nws cov paj huam epic, Ntawm cov ntxhais ntawm Albion visions, William Blake kev xav txog qhov xwm ntawm tus nco, nws muaj peev xwm peb coj peb mus deb lub sij hawm thiab qhov chaw, thiab tus cwj pwm txawv haib, ob leeg zoo thiab tsis zoo, tias peb koom yuav evoke. Cov paj huam muaj cov lus nug uas nyob raus heev hnub no, xws li cas rau puas uas muaj ploj ntev peb, thiab li ua peb retrieve lawv?

Ntau tshaj ob centuries tom qab, lub mechanisms nco cia thiab nqi yog tus phenomena hauv lub paj hlwb sciences feem sib tshawb nrhiav. Nws muaj lug ntseeg uas cim xeeb uas muaj yuav cov strengthening kev sib rau zoo rau tes hauj lwm ntawm neurons nyob hauv ib lub hlwb qauv sparsely distributed hu ua tus hippocampus, thiab nqi tom yuav ntawm tus qub neuronal ensembles reactivation. Thiab tsis tau, neuroscientists tseem zog mas nws yeej teb lus nug tus Blake.

Tam sim no, ib pab soj ntsuam ntawm ntawm lub tsev kawm ntawv ntawm Geneva tau ua dua ib yam tseem ceeb ua ntej hauv peb txoj kev tau taub ntawm cov mechanisms neural lwm nco tag. Siv ib hom hu ua optogenetics xeev-ntawm-tus-daim duab, lawv qhia li cas rau neuronal ensembles uas encode puas hmu, revealing tus ensembles uas muaj ntau neurons – los yog ob peb heev – mus tsis tau nqi nco.

Optogenetics yog ib tug txheej txheem haib kawg uas yuav plaug algal proteins uas hu ua channelrhodopsins (ChRs) rau hauv neurons. Qhov lub hlwb rhiab rau teeb renders, xws li uas sau tseg qhia rau ib pawg uas lawv yuav tsum switched los sis tawm, siv pulses laser ci tauj mus rau ntawm lub hlwb ntawm fibres kho qhov muag, nyob rau lub timescale ntawm milliseconds.

Xyoo tsis ntev los no, soj ntsuam ntawm tau siv optogenetics tau ntawv ua hippocampal neurons uas ua kev mob thaum uas cim xeeb muaj lub paj hlwb nas, thiab muab cov labelled ensembles ntau txoj kev. Ua li no, lawv yuav leg ntaubntawv tus qub ensembles rau induce nco nqi; hloov fearful puas los sis tshem; hloov ua lwm yam tsis zoo puas rau sawv daws yuav zoo, los yog vice versa; thiab cov qab cuav nkaus puas muab cog rau hauv lub qhov ntawm nas.

Txoj kev soj ntsuam tshiab, coj Pablo Mendez thiab cov Dominique Muller lig, leej twg tragically tuag ib gliding sib tsoo nyob rau lub plaub hlis xyoo tas los no, daim no ua hauj lwm ua ntej lawm. Engineered txhob kaw nas hnov txog ChR nyob hauv granule cov hlwb ntawm ib sab ntawm koj lub hlwb tsim lawv, nyob rau lub thaj av dentate ntawm qhov hippocampus. Granule hlwb muaj cov neurons tso nyob hauv lub hippocampus no Lakes, uas yog xav kom tau zoo rau hippocampal nws qhov kev siv cim xeeb thiab spatial navigation. Lawv muab cov tsiaj mus rau hauv lub tawb loj, uas tshawb kev tshiab ib puag ncig lawv tej. Meanwhile, lawv tshuab txais optogenetically random granule hlwb tej tus nas, tab sis tsis yog lwm leej lwm tus.

Hippocampal granule hlwb hnov txog Channelrhodopsin (rau liab).
Hippocampal granule hlwb hnov txog Channelrhodopsin (rau liab). Duab: Pablo Mendez

Thaum twg lawv dissected thiab nais maum kuaj cov tsiaj cov plaw 45 feeb tom qab, Cov soj ntsuam ntawm spatial kev evoked kev ua nyob rau ntawm hippocampal neurons ensembles, raws li muab raws seb cFos, ib tug sib ' tam sim ntawd thaum ' lub noob uas yog switched rau sai thaum neurons pib rau hluav taws. Ceeb tshaj, nas mus tshawb tau lawv lub tawb lawm muaj ntau tus najnpawb ntawm cFos-hnov txog granule hlwb tsawg dua qhov uas nyob rau hauv lawv lub tawb lawm tsev rau qhov xyaum ua tej yam li, thiab muaj dua ho tooj ntawm cov neeg uas tau txais optogenetic stimulation nyob hauv kev tshawb kawm cFos-zoo neurons dua cov uas tsis ua.

Qhov no kuj spatial kev evokes kev ua nyob hauv ensembles cov hlwb dentate granule, thiab tus across Process qhov hauj lwm los ntawm cov tes hauj lwm uas optogenetic stimulation ntawd luaj li cas ntawm cov ensembles, los yog cov hlwb li lawv.

Tiam sis manipulating tus me me ntawm tus ensembles puas muaj ntxim rau behaviour? Paub, Mendez thiab nws lug txhawb cov miv nas hnov txog ChR hauv lawv hippocampi rau hauv ib lub tawb tso rau, pub ntau yam electric shocks. Cov ntawm no kho repetition, tus nas sai paub ntshai lub tawb, thiab sai khov thaum rov qab mus rau nws, Txawm tias thaum lawv tsis muab ntxiv shocks.

Lub sij hawm no, Cov soj ntsuam ntawm optogenetically stimulated random granule hlwb tej tus nas, tab sis tsis yog lwm leej lwm tus, thaum txoj kev kawm, thiaj li yuav ua rau kom qhov luaj li cas neuronal cov khaub ncaws ntau uas encodes lub cim xeeb fearful. Cov nas tshaaj tsawg freezing behaviour thaum rov qab mus rau lub qub tawb tshaj lwm leej lwm tus uas tsis muaj stimulation. Tab sis cov stimulation kuj tsim puas ntshai dag, xws li tus tsiaj froze nyob rau lwm lub sijhawm, heev.

Inhibition ntawm random granule hlwb muaj cov nyhuv tib, suggesting uas pawg Process neurons nyob rau hauv cov khaub ncaws ntau ntau lub teeb nrog cov tsiaj cov muaj peev xwm kom nco qab ntawm puas fearful. Cov kev tshawb pom muaj tej nyiaj uas cov kev kawm ua ntej lawm, uas tseem tsom qhov inhibiting los yog stimulating granule ntawm kev ua impairs contextual kev kawm.

Vim li cas qhov no tej zaum yuav, Cov soj ntsuam ntawm tau lwm series ntawm thwmsim, siv microelectrodes los teev cov kev ua ntawm neurons nyob rau ntawm daim ntaub hippocampal slices. Cov thwmsim tsom optogenetic stimulation cov hlwb granule ua ib robust qhov lus teb rau neighbouring 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 txhob nkag tau los hauv cov khaub ncaws ntau. Ua li no, interneurons li lawv tswj tshiab khiv-ua puas yog regulating tus xov tooj thiab tis ntawm granule hlwb txuam nrog encoding puas. Activating los yog silencing random granule hlwb upsets txoj kev no thiab alters cov hlwb granule, uas tau ua cov tshiab puas tsis ruaj tsis khov.

"Nyob rau hauv txoj kev tshawb no, peb siv ib yam yooj yooj yim nco, lub cim xeeb los ntawm lub ntsiab lus teb spatial, tab sis, cov kev sib tw kawm ntau npaum li cas txoj yaam puab paub memorized, thiab ua li cas rau lub hlwb deals nrog cov kua muaj ntau yaam puab paub,"hais Mendez. "To taub cov lus nug no yuav pab kom peb nkag siab yus lub peev xwm cia rau lub hlwb."

Siv

Stefanelli, T., al li. (2016). Hippocampal Somatostatin Interneurons tswj qhov luaj li cas nco Neuronal Ensembles. Neuron, 89: 1-12. DOI: 10.1016/j.neuron.2016.01.024 [Paub daws teeb]

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