ABOUT THE SPEAKER
Neil Burgess - Neuroscientist
At University College in London, Neil Burgess researches how patterns of electrical activity in brain cells guide us through space.

Why you should listen

Neil Burgessis is deputy director of the Institute of Cognitive Neuroscience at University College London, where he investigates of the role of the hippocampus in spatial navigation and episodic memory. His research is directed at answering questions such as: How are locations represented, stored and used in the brain? What processes and which parts of the brain are involved in remembering the spatial and temporal context of everyday events, and in finding one's way about?

To explore this space, he and his team use a range of methods for gathering data, including pioneering uses of virtual reality, as well as computational modelling and electrophysiological analysis of the function of hippocampal neurons in the rat, functional imaging of human navigation, and neuropsychological experiments on spatial and episodic memory.

A parallel interest: Investigating our human short-term memory for serial order, or how we know our 123s.

More profile about the speaker
Neil Burgess | Speaker | TED.com
TEDSalon London Spring 2011

Neil Burgess: How your brain tells you where you are

Neil Burgess: Como che di o teu cerebro onde estás

Filmed:
1,458,267 views

Como lembramos onde aparcamos o coche? Como sabemos se nos movemos na dirección correcta? O neurocientífico Neil Burgess estuda os mecanismos neuronais que trazan o mapa do espazo que nos rodea e como se relacionan coa memoria e a imaxinación.
- Neuroscientist
At University College in London, Neil Burgess researches how patterns of electrical activity in brain cells guide us through space. Full bio

Double-click the English transcript below to play the video.

00:15
When we park in a big parking lot,
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Cando aparcamos nun estacionamento grande,
00:17
how do we remember where we parked our car?
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como lembramos onde deixamos o coche?
00:19
Here's the problem facing Homer.
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Este é o problema que ten Homer.
00:22
And we're going to try to understand
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E imos tratar de comprender
00:24
what's happening in his brain.
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o que ocorre no seu cerebro.
00:26
So we'll start with the hippocampus, shown in yellow,
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Comezaremos co hipocampo,
en amarelo,
00:28
which is the organ of memory.
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que é o órgano da memoria.
00:30
If you have damage there, like in Alzheimer's,
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Se se dana, como no alzhéimer,
00:32
you can't remember things including where you parked your car.
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non se lembran cousas
como onde aparcamos.
00:34
It's named after Latin for "seahorse,"
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É o nome en latín para 'cabaliño de mar',
00:36
which it resembles.
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ao que se asemella.
00:38
And like the rest of the brain, it's made of neurons.
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E como o resto do cerebro,
componse de neuronas.
00:40
So the human brain
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O cerebro humano
ten uns cen mil millóns de neuronas.
00:42
has about a hundred billion neurons in it.
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00:44
And the neurons communicate with each other
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As neuronas comunícanse entre si
00:47
by sending little pulses or spikes of electricity
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con pequenos impulsos ou picos eléctricos
00:49
via connections to each other.
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a través das súas conexións.
00:51
The hippocampus is formed of two sheets of cells,
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O hipocampo componse
de dúas capas de células
00:54
which are very densely interconnected.
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densamente conectadas.
00:56
And scientists have begun to understand
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Os científicos comezaron a entender
00:58
how spatial memory works
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como funciona a memoria espacial
01:00
by recording from individual neurons
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rastrexando neuronas individuais
01:02
in rats or mice
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de ratas ou ratos
01:04
while they forage or explore an environment
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ao alimentárense ou exploraren un medio
01:06
looking for food.
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en busca de comida.
01:08
So we're going to imagine we're recording from a single neuron
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Imaxinemos que rexistramos
unha neurona individual
01:11
in the hippocampus of this rat here.
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do hipocampo desta rata.
01:14
And when it fires a little spike of electricity,
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Cando dispara un impulso eléctrico,
01:16
there's going to be a red dot and a click.
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aparece un punto vermello e un clic.
01:19
So what we see
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O que vemos é
01:21
is that this neuron knows
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que esta neurona sabe
01:23
whenever the rat has gone into one particular place in its environment.
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se a rata foi a un lugar
específico do seu medio.
01:26
And it signals to the rest of the brain
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E dálle un sinal ao resto do cerebro
01:28
by sending a little electrical spike.
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enviando un pequeno impulso eléctrico.
01:31
So we could show the firing rate of that neuron
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Así que podemos ver a taxa
de disparos desa neurona
01:34
as a function of the animal's location.
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como unha función localizadora do animal.
01:36
And if we record from lots of different neurons,
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E se rastrexamos
moitas neuronas diferentes,
01:38
we'll see that different neurons fire
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vemos que diferentes neuronas dan sinais
01:40
when the animal goes in different parts of its environment,
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cando o animal vai a sitios diferentes,
01:42
like in this square box shown here.
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como nesta caixa cadrada.
01:44
So together they form a map
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Todas xuntas forman un mapa
01:46
for the rest of the brain,
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para o resto do cerebro,
01:48
telling the brain continually,
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dicíndolle continuamente:
01:50
"Where am I now within my environment?"
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"Onde estou agora no meu contorno?"
01:52
Place cells are also being recorded in humans.
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As células de lugar
tamén se rexistran en persoas.
01:55
So epilepsy patients sometimes need
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Os pacientes de epilepsia
ás veces precisan
01:57
the electrical activity in their brain monitoring.
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que se vixíe a súa actividade
eléctrica cerebral.
02:00
And some of these patients played a video game
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Algúns pacientes xogaron a un videoxogo
02:02
where they drive around a small town.
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no que conducían ao redor dunha vila.
02:04
And place cells in their hippocampi would fire, become active,
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E as células de lugar do hipocampo
dispararían, activaríanse,
02:07
start sending electrical impulses
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comezarían a enviar impulsos eléctricos
02:10
whenever they drove through a particular location in that town.
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cada vez que pasaban
por un punto determinado da vila.
02:13
So how does a place cell know
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Como pode saber unha célula de lugar
02:15
where the rat or person is within its environment?
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onde está a rata ou a persoa
dentro do seu contorno?
02:18
Well these two cells here
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Pois ben, estas dúas células
02:20
show us that the boundaries of the environment
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indícannos que os límites do contorno
02:22
are particularly important.
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son especialmente importantes.
02:24
So the one on the top
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A que está arriba
02:26
likes to fire sort of midway between the walls
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dispara nalgún punto entre as paredes
02:28
of the box that their rat's in.
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da caixa onde está a rata.
02:30
And when you expand the box, the firing location expands.
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E se ampliamos a caixa,
amplíase tamén o lugar destes disparos.
02:33
The one below likes to fire
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A da parte inferior dispara
02:35
whenever there's a wall close by to the south.
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cando atopa unha parede cara ao sur.
02:38
And if you put another wall inside the box,
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E se pomos outra parede na caixa,
02:40
then the cell fires in both place
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a célula dispara a ambos os lados
02:42
wherever there's a wall to the south
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cada vez que haxa unha parede ao sur
02:44
as the animal explores around in its box.
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mentres o animal explora a caixa.
02:48
So this predicts
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Así que isto predí a percepción
02:50
that sensing the distances and directions of boundaries around you --
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das distancias e direccións
dos límites ao redor,
02:52
extended buildings and so on --
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edificios grandes e así...,
02:54
is particularly important for the hippocampus.
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é especialmente importante
para o hipocampo.
02:57
And indeed, on the inputs to the hippocampus,
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E, de feito, nas entradas do hipocampo,
02:59
cells are found which project into the hippocampus,
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hai células que se proxectan no hipocampo,
03:01
which do respond exactly
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que responden exactamente
03:03
to detecting boundaries or edges
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á detección de límites ou bordos
03:06
at particular distances and directions
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en distancias específicas e direccións
03:08
from the rat or mouse
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desde onde a rata ou o rato
03:10
as it's exploring around.
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explora o contorno.
03:12
So the cell on the left, you can see,
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Así que a célula á esquerda, como vedes,
03:14
it fires whenever the animal gets near
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dispara cando o animal se achega
03:16
to a wall or a boundary to the east,
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a unha parede ou límite no leste,
03:19
whether it's the edge or the wall of a square box
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sexa o bordo ou a parede
dun espazo cadrado
03:22
or the circular wall of the circular box
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ou a parede dun espazo circular,
03:24
or even the drop at the edge of a table, which the animals are running around.
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ou mesmo o bordo dunha mesa
cando o animal a percorre.
03:27
And the cell on the right there
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E a célula da dereita
03:29
fires whenever there's a boundary to the south,
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dispara sempre que hai un bordo ao sur,
03:31
whether it's the drop at the edge of the table or a wall
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sexa o bordo dunha mesa ou unha parede
03:33
or even the gap between two tables that are pulled apart.
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ou mesmo o baleiro
entre dúas mesas que se separan.
03:36
So that's one way in which we think
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Esa é unha forma en que pensamos
03:38
place cells determine where the animal is as it's exploring around.
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que as células de lugar determinan
onde está o animal mentres explora.
03:41
We can also test where we think objects are,
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Podemos probar tamén
onde cremos que están os obxectos,
03:44
like this goal flag, in simple environments --
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como esta bandeira, en medios simples,
03:47
or indeed, where your car would be.
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ou mesmo, onde deberiamos ter o coche.
03:49
So we can have people explore an environment
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Pode haber xente que explore un medio
03:52
and see the location they have to remember.
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e observe a posición que ten que lembrar.
03:55
And then, if we put them back in the environment,
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E, se os levamos outra vez ao medio,
03:57
generally they're quite good at putting a marker down
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xeralmente son bastante bos ao marcar
03:59
where they thought that flag or their car was.
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onde pensaron que estaría
a bandeira ou o coche.
04:02
But on some trials,
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Pero nalgunhas probas,
04:04
we could change the shape and size of the environment
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poderiamos cambiar
a forma e o tamaño do medio
04:06
like we did with the place cell.
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como fixemos coa célula de lugar.
04:08
In that case, we can see
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Nese caso, podemos ver
04:10
how where they think the flag had been changes
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como cambia onde pensan
que estaba a bandeira,
04:13
as a function of how you change the shape and size of the environment.
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en función de como cambiamos
a forma e o tamaño do medio.
04:16
And what you see, for example,
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Vemos, por exemplo,
04:18
if the flag was where that cross was in a small square environment,
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se a bandeira estaba onda a cruz
dun espazo pequeno cadrado
04:21
and then if you ask people where it was,
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e lle preguntamos á xente onde estaba
04:23
but you've made the environment bigger,
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pero aumentamos o espazo,
04:25
where they think the flag had been
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o lugar onde crían que estaba a bandeira
04:27
stretches out in exactly the same way
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amplíase exactamente da mesma maneira
04:29
that the place cell firing stretched out.
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que os disparos da célula de lugar.
04:31
It's as if you remember where the flag was
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É coma se lembrásedes
onde estaba a bandeira
04:33
by storing the pattern of firing across all of your place cells
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gardando o patrón de disparos
a través das células de lugar
04:36
at that location,
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nesa posición,
04:38
and then you can get back to that location
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e puidésedes volver á posición
04:40
by moving around
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movéndovos
ata facer coincidir o padrón actual
das células de lugar
04:42
so that you best match the current pattern of firing of your place cells
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04:44
with that stored pattern.
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co outro padrón almacenado.
04:46
That guides you back to the location that you want to remember.
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Iso guíanos de volta
á posición que queremos lembrar.
04:49
But we also know where we are through movement.
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Pero tamén sabemos onde estamos
a través do movemento.
04:52
So if we take some outbound path --
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Se collemos un camiño de saída,
04:54
perhaps we park and we wander off --
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quizais aparcamos e damos unha volta,
04:56
we know because our own movements,
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sabemos polos nosos movementos,
04:58
which we can integrate over this path
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que podemos integrar nese camiño,
05:00
roughly what the heading direction is to go back.
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cal é a dirección para volver.
05:02
And place cells also get this kind of path integration input
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E as células de lugar
tamén integran esa información
05:06
from a kind of cell called a grid cell.
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a través dun tipo de célula
chamada célula grella.
05:09
Now grid cells are found, again,
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As células grella tamén se atopan
05:11
on the inputs to the hippocampus,
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nas entradas ao hipocampo,
05:13
and they're a bit like place cells.
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son un pouco como as células de lugar.
05:15
But now as the rat explores around,
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Pero neste caso cando a rata explora,
05:17
each individual cell fires
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cada célula individual dispara
05:19
in a whole array of different locations
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a un rango de lugares moi diferentes
05:22
which are laid out across the environment
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que están espallados polo medio
05:24
in an amazingly regular triangular grid.
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nunha impresionante rede triangular.
05:29
And if you record from several grid cells --
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E se rastrexades varias células grella,
05:32
shown here in different colors --
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aquí en diferentes cores,
05:34
each one has a grid-like firing pattern across the environment,
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cada unha ten un padrón de disparos
nese medio como unha rede
05:37
and each cell's grid-like firing pattern is shifted slightly
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e o padrón de disparos
de cada célula rede cambia lixeiramente
05:40
relative to the other cells.
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en relación coas outras células.
05:42
So the red one fires on this grid
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Así que a vermella dispara nesta rede
05:44
and the green one on this one and the blue on on this one.
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e a verde nesta e a azul nesta.
05:47
So together, it's as if the rat
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E xuntas, é coma se a rata
05:50
can put a virtual grid of firing locations
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fixese unha rede
virtual de posicións de disparos
05:52
across its environment --
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por todo o medio,
05:54
a bit like the latitude and longitude lines that you'd find on a map,
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un pouco como as liñas de latitude e
lonxitude que hai nun mapa
05:57
but using triangles.
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pero con triángulos.
05:59
And as it moves around,
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E ao moverse,
06:01
the electrical activity can pass
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a actividade eléctrica pode pasar
06:03
from one of these cells to the next cell
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desde unha destas células á próxima
06:05
to keep track of where it is,
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para seguir a pista de onde está,
06:07
so that it can use its own movements
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para que poida usar os propios movementos
06:09
to know where it is in its environment.
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e saber onde está no contorno.
06:11
Do people have grid cells?
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A xente ten células grella?
06:13
Well because all of the grid-like firing patterns
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Ben, que todos os padróns
que disparan en rede
06:15
have the same axes of symmetry,
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teñan os mesmos eixes de simetrías,
06:17
the same orientations of grid, shown in orange here,
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a mesma orientación da rede,
en laranxa aquí,
06:20
it means that the net activity
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quere dicir que a actividade
06:22
of all of the grid cells in a particular part of the brain
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de todas as células grella
nun lugar particular do cerebro
06:25
should change
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debería cambiar
06:27
according to whether we're running along these six directions
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segundo esteamos correndo
nestas seis direccións
06:29
or running along one of the six directions in between.
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ou nunha das seis direccións intermedias.
06:32
So we can put people in an MRI scanner
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Podemos poñer xente nun escáner IRM
06:34
and have them do a little video game
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e darlle un pequeno videoxogo
06:36
like the one I showed you
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como o que vos amosei
06:38
and look for this signal.
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e buscar este sinal.
06:40
And indeed, you do see it in the human entorhinal cortex,
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E vedes no córtex entorrinal humano,
06:43
which is the same part of the brain that you see grid cells in rats.
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que está na mesma parte do cerebro
que as células grella das ratas.
06:46
So back to Homer.
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Así que volvendo a Homer.
06:48
He's probably remembering where his car was
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Estará lembrando onde puxo o coche
06:50
in terms of the distances and directions
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en termos de distancias e direccións
06:52
to extended buildings and boundaries
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cara a edificios extensos e límites
06:54
around the location where he parked.
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ao redor da posición onde aparcou.
06:56
And that would be represented
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E iso estará representado
06:58
by the firing of boundary-detecting cells.
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polos disparos de células
detectoras de límites.
07:00
He's also remembering the path he took out of the car park,
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Tamén estará lembrando o camiño
que colleu fóra do aparcamento,
07:03
which would be represented in the firing of grid cells.
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que estará representado
nos disparos de células grella.
07:06
Now both of these kinds of cells
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Ambos os tipos de células
07:08
can make the place cells fire.
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poden facer disparar as células.
07:10
And he can return to the location where he parked
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E el pode volver ao lugar onde aparcou
07:12
by moving so as to find where it is
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movéndose para atopalo
07:15
that best matches the firing pattern
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ata que encaixe o padrón de disparos
07:17
of the place cells in his brain currently
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das células de lugar
07:19
with the stored pattern where he parked his car.
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co padrón almacenado
de onde aparcou o seu coche.
07:22
And that guides him back to that location
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E iso guíao de volta á posición
07:24
irrespective of visual cues
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independentemente das pistas visuais
07:26
like whether his car's actually there.
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coma se o seu coche estivese alí.
07:28
Maybe it's been towed.
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Pode que llo levara o guindastre.
07:30
But he knows where it was, so he knows to go and get it.
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Pero el sabe onde estaba, así
que sabe onde ir e collelo.
07:33
So beyond spatial memory,
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Máis alá da memoria espacial,
07:35
if we look for this grid-like firing pattern
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se buscamos este padrón rede
07:37
throughout the whole brain,
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a través de todo o cerebro,
07:39
we see it in a whole series of locations
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vémolo nunha serie de posicións
07:42
which are always active
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que están sempre activas
ao facermos tarefas
de memoria autobiográfica,
07:44
when we do all kinds of autobiographical memory tasks,
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07:46
like remembering the last time you went to a wedding, for example.
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como lembrar a última vez
que fomos a unha voda.
07:49
So it may be that the neural mechanisms
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Pode que os mecanismos neuronais
07:51
for representing the space around us
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para representar o espazo ao noso redor
07:54
are also used for generating visual imagery
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se usen tamén
para xerar imaxinaría visual,
07:58
so that we can recreate the spatial scene, at least,
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para que poidamos recrear
a escena espacial, polo menos,
08:01
of the events that have happened to us when we want to imagine them.
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dos eventos que nos ocorreron
cando os imaxinamos.
08:04
So if this was happening,
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Se isto ocorrese,
08:06
your memories could start by place cells activating each other
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as vosas memorias comezarían
activando entre si as células de lugar
08:09
via these dense interconnections
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a través desas densas conexións
08:11
and then reactivating boundary cells
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e reactivando células límite
08:13
to create the spatial structure
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para crear a estrutura espacial
08:15
of the scene around your viewpoint.
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ao redor da vosa perspectiva.
08:17
And grid cells could move this viewpoint through that space.
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E as células grella poderían
mover a perspectiva no espazo.
08:19
Another kind of cell, head direction cells,
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Outro tipo de célula,
as de dirección da cabeza,
08:21
which I didn't mention yet,
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que aínda non mencionei,
08:23
they fire like a compass according to which way you're facing.
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disparan como un compás
de acordo co camiño que seguides.
08:26
They could define the viewing direction
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Poden definir a dirección da vista
08:28
from which you want to generate an image for your visual imagery,
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desde onde queredes xerar unha imaxe
para a vosa imaxinaría visual,
08:31
so you can imagine what happened when you were at this wedding, for example.
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así que podedes imaxinar
o que ocorreu nesa voda, por exemplo.
08:34
So this is just one example
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Isto é só un exemplo
08:36
of a new era really
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dunha nova era
08:38
in cognitive neuroscience
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da neurociencia cognitiva,
08:40
where we're beginning to understand
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cando comezamos a entender
08:42
psychological processes
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procesos psicolóxicos,
08:44
like how you remember or imagine or even think
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como o xeito en que lembramos
ou imaxinamos ou mesmo pensamos
08:47
in terms of the actions
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en termos de accións
08:49
of the billions of individual neurons that make up our brains.
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dos centos de miles de neuronas
individuais que forman o cerebro.
08:52
Thank you very much.
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Moitas grazas.
08:54
(Applause)
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(Aplausos)
Translated by Carme Paz
Reviewed by Xusto Rodriguez

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ABOUT THE SPEAKER
Neil Burgess - Neuroscientist
At University College in London, Neil Burgess researches how patterns of electrical activity in brain cells guide us through space.

Why you should listen

Neil Burgessis is deputy director of the Institute of Cognitive Neuroscience at University College London, where he investigates of the role of the hippocampus in spatial navigation and episodic memory. His research is directed at answering questions such as: How are locations represented, stored and used in the brain? What processes and which parts of the brain are involved in remembering the spatial and temporal context of everyday events, and in finding one's way about?

To explore this space, he and his team use a range of methods for gathering data, including pioneering uses of virtual reality, as well as computational modelling and electrophysiological analysis of the function of hippocampal neurons in the rat, functional imaging of human navigation, and neuropsychological experiments on spatial and episodic memory.

A parallel interest: Investigating our human short-term memory for serial order, or how we know our 123s.

More profile about the speaker
Neil Burgess | Speaker | TED.com

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