Thank you so much that I'm allowed to come here and present some data from my lab.
And I will start with the beginning when I was a child.
This is not me, obviously, but as a child, I really wondered: Why do we behave like we
do?
What happens inside us when we learn, when we act?
And I was so lucky that coming from this remote place in Norway, I was allowed to take an
education so that I became a neuroscientist so I could address such questions in my own
lab.
And I just wonder: Do you want to join me on a journey into the brain and dig in and
see what we find?
So if we go into the brain, we see that it consists of brain cells.
These cells, they need to talk to each other, and they talk to each other by sending tiny
electrical signals along the cell, and then, at the end of the cell, there are some chemicals
that are released to the other cell so that it can respond.
And we can use tiny sensors close to these cells and ask them, "What are you doing when
an animal or human is moving or acting or thinking or remembering?"
So it started with this structure.
It's a beautiful structure deep, deep in the brain.
It's called the hippocampus.
And I hope that if you don't remember anything from this Zeitgeist, you'll remember this
hippocampus.
It's a sea horse.
It looks like a sea horse, as you see.
And if you don't have two of these hippocampi, you will not remember a single word of what
I told you today because you need active cells in this structure in order to encode new memories
and objects, facts, new faces, new names, and also to remember what you had for breakfast
this morning.
And we can go into such structures and try to understand how the cells talk to each other
when this structure is producing our memories.
And that is what I try to tell you today.
So it started when I was invited to London, together with my ex-husband, and we had a
fantastic period with John O'Keefe, who we earned the Nobel Prize with, and he trained
us to go into this structure and then record the small electrical potentials.
And he did that in the '60s, and he had just heard about this structure that you needed,
to remember.
So you can imagine, so he just put in these sensors, and the animal was just running around
and he was listening to the cell (making sound), and sometimes the cell was active and sometimes
it wasn't.
And sometimes the activity was increasing a lot (making sound), and then it was silent.
And he was sitting there like a child and he was trying to understand: Why is this cell
active here and why is this cell silent here?
And what he finally figured out was that it's something about the space.
And when he recorded -- not he, but other people recorded more than a hundred cells
at the same time for some time, they could even predict where the animal was with a 5-centimeter
precision.
That's amazing.
So Edvard and I, we were so excited to learn about this technique, so when we moved back
to Trondheim, we wanted to understand what kind of information is this structure getting
from the rest of the brain, and we did a lot of control experiments.
And people said, "Don't do this because there's nothing," but we are stubborn, persistent,
we had the passion, and we went on.
And now I'm going to show you a beauty.
This one.
Can you figure out what it is?
This is -- [ Laughter ]
So this is just a recording from a rat.
There is a camera above the rat, and that is figuring out where the rat has moved.
And the black lines, that is just the path of the animal.
Then the blue dots, that are the tiny electrical signals that is going from one cell to the
next.
This is just recording from one cell.
What is so amazing here is that this structure is so deep into the brain, so this structure
has no eyes, it doesn't have ears, it doesn't have a nose, and even though it doesn't have
all these sensory direct inputs, it knows where to be active and where to be silent.
And not even that, you see you can even fit in an equilateral triangle into this pattern.
And that's crazy because this is biology; this is not artificial intelligence.
And you can just tile your bathroom with this pattern.
It's so beautiful.
You agree?
[ Laughter ] So our next question was: How is this possible?
This cell needs to get input, both about the direction that the animal is moving but also
the speed, because our animals, they are so happy, they are chasing chocolate and they're
running around, they stop, and they look up and do all these things, so there has to be
this input.
So in 2006, we had a wonderful post-doc in the lab, Francesca Sargolini, and she discovered
the compass cells also in this structure.
Compass cells, or head direction cells, had been shown in another structure earlier by
Taube and Jim Ranck in '85 and 1990, but now this head direction signal is located close
to this cell that we call the grid cell.
And this cell works so that even if the animal is just standing still, one cell would then
be active in that direction (making sound), and then, turning away, nothing, and then
(making sound), and then different cells, like a compass, would then signal different
directions.
And that is what you see here on the figure that I tried to make with this mouse.
Another signal that we need in order to make a perfect grid pattern, that is the speed
input.
So do you think there is a speedometer in our brains?
I think so because they exist in the rat.
So when the rat is driving a car in the lab, then it has to run so that it's moving but
we decide the speed of the car.
And what you see in this figure, it's a bit complicated and I see I don't have that much
time, but what you see here is that each line here is one lap.
So when the animal is either driving north or south.
And then on these lines, there are red dots and that is just electrical potential.
What I want you to see is that in the upper panel, you have the gray lines and the red
lines, and the gray lines, that is just the speed of this car, and the red is just the
summed activity of this electrical potential in one cell.
So that means that if you record speed cells in my brain now, then it will be like this.
If I'm running fast sound, (making sound).
Stopping, nothing.
So it's a perfect speedometer in the brain.
So this is integrated, this information is integrated, into the cell, and that makes
this cell, without eyes and other direct sensory input able to fire in this fantastic, precise
pattern.
You know that space and memories are linked, and I tested this.
This is a figure made by my daughter very fast.
People know about the memory palace technique, so you can use that to memorize boring words
or something like that.
And this is just an illustration of how you could, for example, learn about the different
countries in South America and where they are, related to each other.
And you see the boulevard.
That's my car.
And my dog here in the middle, that is for Bolivia and so on.
So you can both separate the memories in the different rooms and you can do a mental travel
in order to pick up the different objects or different facts that you want to learn.
And we have object cells in our brain, so this is the entorhinal cortex, and this is
an experiment not from our lab from Jim Knierim's lab, where he shows that when you give the
animal objects in the room, then there would then be active around that object, as you
see here.
So blue here is no activity, and then you have the warmer colors.
That is high-firing activity.
We even have traces cells, so these cells, they respond to the previous location of an
object.
So you just train the animal that there is an object in the room and then you remove
it and then this cell would say, "At this position, there was an object."
And this is important for our memory.
So what we have shown in our lab is that into this hippocampus, the hippocampus is receiving
information from the entorhinal cortex, and you have the metric from the middle entorhinal
cortex making the frame of the memory palace, and then you have the object from another
path of the lateral entorhinal cortex, and this information is integrated in the hippocampus.
And if I had had more time, I could even tell how this integration happens.
And then to end, I just want to bring you even further into the brain.
So this is the last slide, and what happens here is that as you heard Jennifer, you can
go in and engineer cells to do strange things.
So she had a green frog.
We have green cells that will show when they're active, and we can just have a tiny window
on the skull and we can look at the cells when the animal is moving around, and this
is what you see here.
And I think red means that I'm over time -- [ Laughter ]
I'm sorry.
So this is what I wanted to show you then.
Thank you so much.