Neil Burgess: How your brain tells you where you are

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When we park in a big parking lot,

Kada parkiramo na velikom parkiralištu,

how do we remember where we parked our car?

kako se sjetimo gdje smo ostavili auto?

Here's the problem facing Homer.

Ovaj problem muči Homera.

And we're going to try to understand

Pokušat ćemo razumjeti

what's happening in his brain.

što se događa u njegovom mozgu.

So we'll start with the hippocampus, shown in yellow,

Počnimo s hipokampusom, koji je obojan žuto,

which is the organ of memory.

i organ je memorije.

If you have damage there, like in Alzheimer's,

Ako imate neko oštećenje na tom području, kao kod Alzheimerove bolesti,

you can't remember things including where you parked your car.

ne možete zapamtiti stvari poput toga gdje ste parkirali.

It's named after Latin for "seahorse,"

Hipokampus je dobio ime po latinskom nazivu za morskog konjica,

which it resembles.

na kojeg izgledom podsjeća.

And like the rest of the brain, it's made of neurons.

Kao i ostatak mozga, načinjen je od neurona.

So the human brain

Ljudski mozak

has about a hundred billion neurons in it.

sadrži otprilike stotinu milijardi neurona.

And the neurons communicate with each other

Ti neuroni međusobno komuniciraju,

by sending little pulses or spikes of electricity

šalju si male električne signale

via connections to each other.

preko različitih veza kojima su povezani.

The hippocampus is formed of two sheets of cells,

Hipokampus se sastoji od dvije ploče stanica

which are very densely interconnected.

koje su vrlo gusto povezane.

And scientists have begun to understand

Znanstvenici su počeli shvaćati

how spatial memory works

kako funkcionira prostorna memorija

by recording from individual neurons

snimajući aktivnost pojedinih neurona

in rats or mice

kod štakora ili miševa

while they forage or explore an environment

koji su istraživali okolinu

looking for food.

u potrazi za hranom.

So we're going to imagine we're recording from a single neuron

Sada ćemo zamisliti da snimamo aktivnost jednog neurona

in the hippocampus of this rat here.

u hipokampusu ovog štakora ovdje.

And when it fires a little spike of electricity,

Kada neuron bude odaslao jedan impuls elektriciteta,

there's going to be a red dot and a click.

ovdje ćemo vidjeti crvenu točku i začuti klik.

So what we see

Vidimo da

is that this neuron knows

taj neuron zna

whenever the rat has gone into one particular place in its environment.

je li štakor otišao na točno određeno mjesto u okolini.

And it signals to the rest of the brain

I šalje signal ostatku mozga

by sending a little electrical spike.

tim jednim električnim impulsom.

So we could show the firing rate of that neuron

Dakle, možemo prikazati jačinu tog impulsa

as a function of the animal's location.

kao funkciju lokacije životinje.

And if we record from lots of different neurons,

I ako snimimo aktivnost više neurona,

we'll see that different neurons fire

vidjet ćemo da različiti neuroni šalju impulse

when the animal goes in different parts of its environment,

kako životinja ide u različite dijelove okoline,

like in this square box shown here.

kao u ovom kvadratiću ovdje.

So together they form a map

Zajedno, oni čine mapu

for the rest of the brain,

za ostatak mozga,

telling the brain continually,

neprekidno govoreći mozgu,

"Where am I now within my environment?"

“Gdje se sada nalazim unutar moje okoline?”

Place cells are also being recorded in humans.

Aktivnost stanica zaduženih za lociranje također je snimana i kod ljudi.

So epilepsy patients sometimes need

Osobe koje boluju od epilepsije katkada trebaju

the electrical activity in their brain monitoring.

električnu aktivnost pri nadziranju moždanih funkcija.

And some of these patients played a video game

Neki od njih su igrali video igricu

where they drive around a small town.

u kojoj voze auto po malenom gradiću.

And place cells in their hippocampi would fire, become active,

Stanice njihovog hipokampusa bi odaslale impuls, aktivirale se

start sending electrical impulses

i slale signal

whenever they drove through a particular location in that town.

kad god bi oni provezli auto kroz točno određeno mjesto u tom gradiću.

So how does a place cell know

Kako stanica za lociranje zna

where the rat or person is within its environment?

gdje se štakor ili osoba nalaze?

Well these two cells here

Ove dvije stanice ovdje

show us that the boundaries of the environment

pokazuju nam da su granice okoline

are particularly important.

osobito važne.

So the one on the top

Ova gornja

likes to fire sort of midway between the walls

voli slati signal s polovice puta između zidova

of the box that their rat's in.

kutije u kojoj se štakor nalazi.

And when you expand the box, the firing location expands.

A kada proširite kutiju, i preferirana lokacija za odašiljanje signala se proširi.

The one below likes to fire

Donja stanica voli slati signal

whenever there's a wall close by to the south.

uvijek kada postoji zid u blizini juga.

And if you put another wall inside the box,

I ako postavite još jedan zid u kutiju,

then the cell fires in both place

stanica će slati signal s oba mjesta,

wherever there's a wall to the south

gdje god je zid u blizini juga,

as the animal explores around in its box.

kako životinja bude istraživala oko kutije.

So this predicts

Ovo ukazuje

that sensing the distances and directions of boundaries around you --

kako je osjećaj za udaljenost i smjer u kojem se nalaze granice oko vas

extended buildings and so on --

(u proširenom smislu zgrade itd.)

is particularly important for the hippocampus.

povezan s hipokampusom.

And indeed, on the inputs to the hippocampus,

I zaista, jedan od aferentnih putova za hipokampus,

cells are found which project into the hippocampus,

stanice koje šalju projekcije u hipokampus,

which do respond exactly

reagiraju upravo

to detecting boundaries or edges

detektirajući granice i rubove

at particular distances and directions

na posebnim udaljenostima i pravcima

from the rat or mouse

od štakora ili miša

as it's exploring around.

dok istražuje uokolo.

So the cell on the left, you can see,

Stanica s lijeve strane, kao što vidite,

it fires whenever the animal gets near

odašilje signal kada se životinja nađe kod

to a wall or a boundary to the east,

zida ili granice blizu istoka,

whether it's the edge or the wall of a square box

bio to ugao ili zid četvrtaste kutije,

or the circular wall of the circular box

zaobljen zid okrugle kutije

or even the drop at the edge of a table, which the animals are running around.

ili pak rub stola po kojem životinja hoda.

And the cell on the right there

Stanica desno

fires whenever there's a boundary to the south,

odašilje signal kada postoji granica prema jugu,

whether it's the drop at the edge of the table or a wall

bio to rub stola

or even the gap between two tables that are pulled apart.

ili mali prostor između dva spojena stola.

So that's one way in which we think

Mislimo kako je to jedan od načina

place cells determine where the animal is as it's exploring around.

na koji stanice za lociranje određuju gdje se životinja nalazi.

We can also test where we think objects are,

Možemo testirati i osjećaj smještanja objekata u prostor,

like this goal flag, in simple environments --

poput ove zastavice, u jednostavnim uvjetima,

or indeed, where your car would be.

tj. gdje bi se mogao nalaziti vaš auto.

So we can have people explore an environment

Na početku imamo ispitanike koji promatraju okolinu

and see the location they have to remember.

i lokaciju koju moraju upamtiti.

And then, if we put them back in the environment,

Kada ih poslije vratimo u istu okolinu,

generally they're quite good at putting a marker down

generalno su prilično dobri u smještanju oznake

where they thought that flag or their car was.

na mjesto na kojem je prije bila zastavica ili auto.

But on some trials,

Možemo mijenjati

we could change the shape and size of the environment

oblik i veličinu okoline

like we did with the place cell.

kao što smo radili sa stanicama za lociranje.

In that case, we can see

U tom slučaju, vidjet ćemo

how where they think the flag had been changes

da se njihovo mišljenje o tome gdje je zastavica bila mijenja

as a function of how you change the shape and size of the environment.

ovisno o promjeni oblika i veličine okoline.

And what you see, for example,

Na primjer,

if the flag was where that cross was in a small square environment,

ako je zastavica bila gdje se nalazi križić u maloj četvrtastoj okolini

and then if you ask people where it was,

i pitamo ljude gdje je bila,

but you've made the environment bigger,

ali povećamo okolinu –

where they think the flag had been

njihova predodžba o mjestu na kojem se zastavica nalazila

stretches out in exactly the same way

se proširuje isto kao što se proširilo

that the place cell firing stretched out.

i područje na kojem stanice za lociranje odašilju impuls.

It's as if you remember where the flag was

Čini se da pamtimo gdje se zastavica nalazila

by storing the pattern of firing across all of your place cells

pohranjujući uzorke odašiljanja impulsa svih stanica

at that location,

za lociranje na toj lokaciji.

and then you can get back to that location

Možemo se vratiti na tu lokaciju

by moving around

kružeći uokolo

so that you best match the current pattern of firing of your place cells

tako što ćemo povezati trenutne uzorke odašiljanja impulsa stanica za lociranje

with that stored pattern.

sa onima koje smo pohranili.

That guides you back to the location that you want to remember.

To nas vodi natrag k lokaciji koju trebamo upamtiti.

But we also know where we are through movement.

Ali također znamo gdje se nalazimo kroz pokret.

So if we take some outbound path --

Ako krenemo nekim izlaznim putem,

perhaps we park and we wander off --

na primjer parkiramo i odlutamo,

we know because our own movements,

sjećamo se svojih pokreta,

which we can integrate over this path

možemo ih ponovno ugrubo integrirati

roughly what the heading direction is to go back.

te pronaći put natrag.

And place cells also get this kind of path integration input

Stanice za lociranje također dobivaju projekciju tog tipa

from a kind of cell called a grid cell.

od tzv. rešetkastih stanica.

Now grid cells are found, again,

Rešetkaste stanice pojavljuju se

on the inputs to the hippocampus,

kao projekcija u hipokampusu

and they're a bit like place cells.

i nalik su stanicama za lociranje.

But now as the rat explores around,

Kako štakor istražuje okolinu,

each individual cell fires

svaka individualna stanica ispaljuje

in a whole array of different locations

na nizu različitih lokacija

which are laid out across the environment

koje su posložene

in an amazingly regular triangular grid.

u nevjerojatno pravilan trokutast oblik.

And if you record from several grid cells --

I ako snimimo aktivnost više različitih rešetkastih stanica –

shown here in different colors --

što vidimo ovdje prikazano različitim bojama –

each one has a grid-like firing pattern across the environment,

svaka ima uzorak nalik rešetki uzduž okoline,

and each cell's grid-like firing pattern is shifted slightly

i svaki taj uzorak je malo pomaknut

relative to the other cells.

u odnosu na uzorke ostalih stanica.

So the red one fires on this grid

Crvena formira ovu rešetku,

and the green one on this one and the blue on on this one.

zelena ovu, a plava ovu.

So together, it's as if the rat

Dakle, to je kao da štakor

can put a virtual grid of firing locations

na temelju svoje okoline sastavlja virtualnu rešetku lokacija

across its environment --

na kojima se odašilje impuls –

a bit like the latitude and longitude lines that you'd find on a map,

nešto poput okomitih i vodoravnih linija koje možete naći na karti,

but using triangles.

samo koristi trokute.

And as it moves around,

Kako se kreće uokolo,

the electrical activity can pass

električna aktivnost prelazi

from one of these cells to the next cell

s jedne na drugu stanicu

to keep track of where it is,

i bilježi gdje se štakor nalazi,

so that it can use its own movements

tako da on može znati gdje se nalazi

to know where it is in its environment.

koristeći vlastite kretnje.

Do people have grid cells?

Imaju li ljudi rešetkaste stanice?

Well because all of the grid-like firing patterns

Budući da svi rešetkasti uzorci impulsa

have the same axes of symmetry,

imaju iste osi simetrije,

the same orientations of grid, shown in orange here,

istu orijentaciju rešetki, što je prikazano ovdje narančasto,

it means that the net activity

to bi značilo da mrežastu aktivnost

of all of the grid cells in a particular part of the brain

svih rešetkastih stanica određenog dijela mozga

should change

možemo mijenjati

according to whether we're running along these six directions

ovisno o tome krećemo li se uzduž jednog od ovih šest pravaca

or running along one of the six directions in between.

ili jednog od šest pravaca između.

So we can put people in an MRI scanner

Ljude možemo podvrgnuti MRI skeniranju

and have them do a little video game

dok igraju video igru

like the one I showed you

poput one koju sam vam pokazao.

and look for this signal.

i tražiti taj signal.

And indeed, you do see it in the human entorhinal cortex,

I zaista, taj signal možete vidjeti u ljudskom entorinalnom korteksu,

which is the same part of the brain that you see grid cells in rats.

koji se nalazi na istom dijelu mozga na kojem kod štakora nalazimo rešetkaste stanice.

So back to Homer.

Vratimo se Homeru.

He's probably remembering where his car was

Vjerojatno se sjeća gdje mu se nalazi auto

in terms of the distances and directions

u smislu udaljenosti te pravca

to extended buildings and boundaries

zgrada i granica

around the location where he parked.

koje okružuju mjesto na kojemu je parkirao.

And that would be represented

I to bismo vidjeli kao odašiljanje signala

by the firing of boundary-detecting cells.

stanica koje detektiraju granice.

He's also remembering the path he took out of the car park,

Također, sjeća se i puta kojim je krenuo s parkirališta,

which would be represented in the firing of grid cells.

a to bismo vidjeli kao odašiljanje signala rešetkastih stanica.

Now both of these kinds of cells

Obje vrste stanica

can make the place cells fire.

mogu dovesti do odašiljanja signala iz stanica za lociranje.

And he can return to the location where he parked

Homer se može vratiti do mjesta gdje se parkirao

by moving so as to find where it is

tražeći mjesto na kojem se

that best matches the firing pattern

trenutno odašiljanje stanica za lociranje

of the place cells in his brain currently

najbolje poklapa

with the stored pattern where he parked his car.

s upamćenim uzorkom odašiljanja signala.

And that guides him back to that location

To ga vodi natrag na lokaciju

irrespective of visual cues

bez obzira na vizualne znakove

like whether his car's actually there.

poput toga je li njegov auto zbilja tamo.

Maybe it's been towed.

Možda ga je pauk odnio.

But he knows where it was, so he knows to go and get it.

Ali on zna gdje je bio, tako da zna i otići po njega.

So beyond spatial memory,

S druge strane,

if we look for this grid-like firing pattern

ako pogledamo ove rešetkaste uzorke

throughout the whole brain,

odašiljanja impulsa kroz cijeli mozak,

we see it in a whole series of locations

vidimo serije lokacija

which are always active

koje su aktivne uvijek

when we do all kinds of autobiographical memory tasks,

kada obavljamo razne zadatke vezane uz autobiografsko sjećanje,

like remembering the last time you went to a wedding, for example.

na primjer prisjećanje kada smo zadnji put bili na vjenčanju.

So it may be that the neural mechanisms

Moguće je da se neuralni mehanizmi

for representing the space around us

za prikazivanje prostora oko nas

are also used for generating visual imagery

koriste ujedno i za generiranje vizualnih slika

so that we can recreate the spatial scene, at least,

kako bismo mogli stvoriti prostorni prizor

of the events that have happened to us when we want to imagine them.

događaja koji su nam se dogodili kada ih se želimo prisjetiti.

So if this was happening,

Ako se to događa na taj način,

your memories could start by place cells activating each other

prisjećanje počinje tako što se stanice za lociranje međusobno aktiviraju

via these dense interconnections

putem gustih komunikacija,

and then reactivating boundary cells

reaktiviraju stanice za detektiranje granica

to create the spatial structure

kako bi stvorile prostornu strukturu

of the scene around your viewpoint.

prizora s vaše točke gledišta.

And grid cells could move this viewpoint through that space.

Rešetkaste stanice pomiču tu točku gledišta kroz prostor.

Another kind of cell, head direction cells,

Još jedna vrsta stanica

which I didn't mention yet,

koju dosad nisam spominjao,

they fire like a compass according to which way you're facing.

stanice koje određuju smjer gibanja glave odašilju impulse poput kompasa ovisno o tome na koju stranu ste okrenuti.

They could define the viewing direction

One definiraju pravac gledanja

from which you want to generate an image for your visual imagery,

s kojeg želite generirati imaginarnu sliku,

so you can imagine what happened when you were at this wedding, for example.

tako da na primjer, možete zamisliti što se događalo kada ste bili na tom vjenčanju.

So this is just one example

Ovo je još jedan dokaz

of a new era really

o novom dobu

in cognitive neuroscience

koje je nastupilo u neuroznanosti,

where we're beginning to understand

gdje počinjemo shvaćati

psychological processes

psihičke procese

like how you remember or imagine or even think

poput toga kako se prisjećamo, kako zamišljamo ili mislimo

in terms of the actions

u okvirima aktivnosti

of the billions of individual neurons that make up our brains.

milijardi individualnih neurona koji sačinjavaju naš mozak.

Thank you very much.

Hvala puno.

(Applause)

(Pljesak)