What happens when you remove the hippocampus? - Sam Kean

Šta se dešava kad uklonimo hipokampus? - Sem Kin (Sam Kean)

Prevodilac: Katarina Jakovljević Lektor: Ivana Korom

On September 1st, 1953,

Prvog septembra 1953. godine,

William Scoville used a hand crank and a cheap drill saw

Vilijam Skovil je iskoristio polugu i jeftinu ručnu bušilicu

to bore into a young man's skull, cutting away vital pieces of his brain

da probuši lobanju mladića i odstrani važan deo njegovog mozga

and sucking them out through a metal tube.

isisavajići ga kroz metalnu cev.

But this wasn't a scene from a horror film or a gruesome police report.

Ovo nije scena iz horor filma ili odvratni policijski izveštaj.

Dr. Scoville was one of the most renowned neurosurgeons of his time,

Dr Skovil je bio jedan od najpriznatijih neurohirurga svog vremena,

and the young man was Henry Molaison, the famous patient known as "H.M.",

a mladić je bio Henri Moleson, poznat kao pacijent "H.M.",

whose case provided amazing insights into how our brains work.

iz čijeg slučaja su proistekli brojni zaključci o tome kako naš mozak radi.

As a boy, Henry had cracked his skull in an accident

Kao dečaku, Henriju je napukla lobanja u nesreći

and soon began having seizures, blacking out and losing control of bodily functions.

i počeo je da dobija napade, nesvestice i gubi kontrolu nad telesnim funkcijama.

After enduring years of frequent episodes, and even dropping out of high school,

Nakon što je godinama trpeo česte epizode i čak se ispisao iz srednje škole,

the desperate young man had turned to Dr. Scoville,

očajan mladić se javio dr Skovilu,

a daredevil known for risky surgeries.

pustolovu poznatom po rizičnim operacijama.

Partial lobotomies had been used for decades to treat mental patients

Parcijalna lobotomija je decenijama unazad korišćena u lečenju duševnih poremećaja,

based on the notion that mental functions were strictly localized

na osnovu pretpostavke da su mentalne funkcije strogo lokalizovane

to corresponding brain areas.

u određenim oblastima mozga.

Having successfully used them to reduce seizures in psychotics,

Pošto ju je uspešno koristio da bi redukovao napade kod psihoza,

Scoville decided to remove H.M.'s hippocampus,

Skovil je odlučio da ukloni H.M.-ov hipokampus,

a part of the limbic system that was associated with emotion

deo limbičkog sistema koji je povezan sa emocijama

but whose function was unknown.

ali čije su funkcije i dalje nepoznate.

At first glance, the operation had succeeded.

Na prvi pogled operacija je bila uspešna.

H.M.'s seizures virtually disappeared, with no change in personality,

H.M.-ovi napadi su praktično prestali bez promena u njegovoj ličnosti,

and his IQ even improved.

a IQ mu se čak i povećao.

But there was one problem: His memory was shot.

Međutim javio se jedan problem. Njegovo pamćenje je bilo oštećeno.

Besides losing most of his memories from the previous decade,

Pored toga što je izgubio većinu uspomena iz prethodne decenije,

H.M. was unable to form new ones, forgetting what day it was,

H.M. nije mogao ni da formira nove, zaboravljao je koji je dan danas,

repeating comments, and even eating multiple meals in a row.

ponavljao je komentare i čak jeo više obroka za redom.

When Scoville informed another expert, Wilder Penfield, of the results,

Kada je Skovil o ovome obavestio drugog stručnjaka, Vajldera Penfilda,

he sent a Ph.D student named Brenda Milner to study H.M. at his parents' home,

on je poslao doktorantkinju Brendu Milner

da proučava H.M. u njegovoj porodičnoj kući,

where he now spent his days doing odd chores,

gde je on provodio svoje vreme obavljajući neobične radnje

and watching classic movies for the first time, over and over.

i gledajući klasične filmove, po prvi put, iznova i iznova.

What she discovered through a series of tests and interviews

Ono što je otkrila, kroz niz testova i intervjua,

didn't just contribute greatly to the study of memory.

nije samo doprinelo proučavanju pamćenja,

It redefined what memory even meant.

već je potpuno redefinisalo značenje pamćenja.

One of Milner's findings shed light on the obvious fact

Jedno od Milnerovih otkrića osvetlilo je očiglednu činjenicu

that although H.M. couldn't form new memories, he still retained information

da iako H.M. ne može da stvori nove uspomene, on ipak pamti informacije

long enough from moment to moment to finish a sentence or find the bathroom.

dovoljno dugo da završi rečenicu ili pronađe kupatilo.

When Milner gave him a random number,

Kada mu je Milnerova pokazala nasumični broj

he managed to remember it for fifteen minutes

uspeo je da ga zapamti na 15 minuta

by repeating it to himself constantly.

tako što ga je stalno ponavljao.

But only five minutes later, he forgot the test had even taken place.

Ali samo pet minuta kasnije, zaboravio je da su uopšte uradili test.

Neuroscientists had though of memory as monolithic,

Neurolozi su smatrali da je pamćenje monolitno,

all of it essentially the same and stored throughout the brain.

u suštini jednako i ravnomerno raspoređeno kroz mozak.

Milner's results were not only the first clue for the now familiar distinction

Rezultati Milnerove ne samo da su bili prvi korak ka danas poznatoj razlici

between short-term and long-term memory,

između kratkoročnog i dugoročnog pamćenja,

but show that each uses different brain regions.

već su pokazali da su oni smešteni u različitim delovima mozga.

We now know that memory formation involves several steps.

Danas znamo da je za stvaranje uspomena potrebno nekoliko koraka.

After immediate sensory data is temporarily transcribed by neurons in the cortex,

Nakon što su senzorne informacije pomoću neurona privremeno stigle u korteks,

it travels to the hippocampus,

one dalje putuju do hipokampusa,

where special proteins work to strengthen the cortical synaptic connections.

gde proteini ojačavaju kortikalne sinaptičke veze.

If the experience was strong enough,

Ukoliko je iskustvo bilo dovoljno jako,

or we recall it periodically in the first few days,

ili ga se u prvih nekoliko dana redovno prisećamo,

the hippocampus then transfers the memory back to the cortex for permanent storage.

hipokampus će onda prebaciti sećanje nazad u korteks gde će biti trajno smešteno.

H.M.'s mind could form the initial impressions,

H.M-ov mozak može da formira početni utisak,

but without a hippocampus to perform this memory consolidation,

ali bez hipokampusa koji bi odradio konsolidaciju sećanja,

they eroded, like messages scrawled in sand.

utisak bledi, poput poruke ispisane u pesku.

But this was not the only memory distinction Milner found.

Ali to nije bila jedina razlika u pamćenju koju je Milnerova našla.

In a now famous experiment, she asked H.M. to trace a third star

U poznatom eksperimentu, ona je pitala H.M. da ocrta treću zvezdu

in the narrow space between the outlines of two concentric ones

u uskom prostoru između dve koncentrične zvezde

while he could only see his paper and pencil through a mirror.

pri čemu je papir i olovku mogao da vidi samo u ogledalu.

Like anyone else performing such an awkward task for the first time,

Poput bilo koga ko izvršava ovako čudan zadatak prvi put,

he did horribly.

i njegov rezultat je bio jako loš.

But surprisingly, he improved over repeated trials,

Ali se kroz više pokušaja popravio, na opšte iznenađenje,

even though he had no memory of previous attempts.

iako se nije sećao prethodnih pokušaja.

His unconscious motor centers remembered what the conscious mind had forgotten.

Njegovi nesvesni motorni centri su zapamtili ono što je svest zaboravila.

What Milner had discovered was that the declarative memory of names, dates and facts

Milnerova je otkrila da je deklarativno pamćenje imena, datuma i činjenica

is different from the procedural memory of riding a bicycle or signing your name.

drugačije od proceduralnog pamćenja, poput vožnje bicikla ili potpisivanja.

And we now know that procedural memory

Danas znamo da se proceduralno pamćenje

relies more on the basal ganglia and cerebellum,

oslanja više na bazalne ganglije i cerebelum,

structures that were intact in H.M.'s brain.

strukture koje su u mozgu H.M.-a bile neoštećene.

This distinction between "knowing that" and "knowing how"

Ova razlika, između "znati šta" i "znati kako"

has underpinned all memory research since.

je uticala na sva kasnija istraživanja.

H.M. died at the age of 82 after a mostly peaceful life in a nursing home.

H.M. je umro u 82. godini nakon uglavnom mirnog života u staračkom domu.

Over the years, he had been examined by more than 100 neuroscientists,

Tokom godina ispitalo ga je preko 100 neurologa,

making his the most studied mind in history.

što čini njegov mozak najviše proučavanim u istoriji.

Upon his death, his brain was preserved and scanned

Nakon smrti, njegov mozak je očuvan i skeniran

before being cut into over 2000 individual slices

pre nego što je podeljen na preko 2000 delova

and photographed to form a digital map down to the level of individual neurons,

i fotografisan, kako bi se napravila digitalna mapa,

na nivou pojedinačnih neurona,

all in a live broadcast watched by 400,000 people.

i sve to u prenosu uživo, koji je pratilo 400,000 ljudi.

Though H.M. spent most of his life forgetting things,

Iako je H.M. proveo veći deo života zaboravljajući stvari,

he and his contributions to our understanding of memory

on i njegovi doprinosi našem razumevanju pamćenja

will be remembered for generations to come.

biće pamćeni generacijama koje dolaze.