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Meet Charlie and Iona. | 0:00:02 | 0:00:03 | |
As you can plainly see, Charlie is much taller than Iona. | 0:00:03 | 0:00:06 | |
But sometimes reality is not what it seems. | 0:00:06 | 0:00:10 | |
Welcome to the 2011 Royal Institution Christmas Lectures, | 0:00:55 | 0:00:59 | |
Meet Your Brain. | 0:00:59 | 0:01:01 | |
Let me introduce myself. | 0:01:01 | 0:01:02 | |
I'm Bruce Hood, and I am a scientist interested in the human brain, | 0:01:02 | 0:01:06 | |
what it is and how it changes as we grow older. | 0:01:06 | 0:01:10 | |
Actually, when I said "I am Bruce Hood" what I really should have said is, "This is Bruce Hood". | 0:01:10 | 0:01:15 | |
Because everything I am is really a product of my brain. | 0:01:15 | 0:01:19 | |
It's not my heart, it's not my kidneys - | 0:01:19 | 0:01:21 | |
these are important organs, but I could have them transplanted | 0:01:21 | 0:01:24 | |
and I'd still be the same person. | 0:01:24 | 0:01:26 | |
That's because it's our brain that makes us who we are. | 0:01:26 | 0:01:30 | |
In this series of lectures, we're going to be looking at the human brain, | 0:01:30 | 0:01:33 | |
what it is, how it works and most importantly, how it interacts with other brains. | 0:01:33 | 0:01:38 | |
But before I do so, I'd like to introduce you to someone else here. | 0:01:38 | 0:01:42 | |
Or rather, someone who is here no longer. | 0:01:42 | 0:01:47 | |
This is a real human brain, from a person. | 0:01:48 | 0:01:52 | |
Before they died, they made the decision to donate their brain to science, | 0:01:54 | 0:01:58 | |
so that we could discover | 0:01:58 | 0:02:00 | |
the workings of this most astonishing, amazing organ. | 0:02:00 | 0:02:05 | |
It is so mysterious and complicated, | 0:02:08 | 0:02:10 | |
we can't even begin to really know how it works! | 0:02:10 | 0:02:13 | |
I brought this brain along tonight to remind you | 0:02:15 | 0:02:18 | |
exactly who we are, and what we are trying to understand. | 0:02:18 | 0:02:22 | |
It is truly awe-inspiring. | 0:02:23 | 0:02:26 | |
Every one of you here tonight, and watching at home, | 0:02:29 | 0:02:32 | |
has a brain inside your head. | 0:02:32 | 0:02:34 | |
Every brain is important. Every brain is unique. | 0:02:34 | 0:02:38 | |
But all brains have the same basic machinery - | 0:02:38 | 0:02:41 | |
so how does a brain work? | 0:02:41 | 0:02:44 | |
To help me answer these questions, | 0:02:44 | 0:02:47 | |
I've invited along another brain scientist, Professor Vince Walsh from UCL. | 0:02:47 | 0:02:51 | |
Give a big round of applause to Vince! | 0:02:51 | 0:02:53 | |
APPLAUSE AND CHEERING | 0:02:53 | 0:02:55 | |
So Vince, you've brought along this special machine | 0:02:59 | 0:03:02 | |
that influences the brain. | 0:03:02 | 0:03:05 | |
We're going to see it in action. | 0:03:05 | 0:03:06 | |
But before we do, let's start with a simple demonstration. | 0:03:06 | 0:03:09 | |
Do you know the Nursery Rhyme "Baa Baa Black Sheep"? | 0:03:09 | 0:03:13 | |
-I think so. -Could you give us the first line? | 0:03:13 | 0:03:15 | |
Baa baa black sheep, have you any wool? | 0:03:15 | 0:03:18 | |
That's good. | 0:03:18 | 0:03:19 | |
Reassuring to know that professors still know their nursery rhymes. | 0:03:19 | 0:03:23 | |
OK. I'm going to get you to repeat that, | 0:03:23 | 0:03:26 | |
but this time, I'm going to stimulate this part of your brain | 0:03:26 | 0:03:30 | |
with your machine. | 0:03:30 | 0:03:31 | |
Start, please. | 0:03:31 | 0:03:33 | |
Baa baa black... | 0:03:33 | 0:03:34 | |
VOICE BECOMES DISTORTED | 0:03:34 | 0:03:36 | |
LAUGHTER | 0:03:36 | 0:03:39 | |
Don't be alarmed. | 0:03:40 | 0:03:41 | |
-You're perfectly OK, Vince, aren't you? -I'm fine, yes. -That's very good. | 0:03:42 | 0:03:46 | |
Somehow this machine has disrupted Vince's brain. | 0:03:46 | 0:03:49 | |
This is a trans-magnetic stimulator. | 0:03:49 | 0:03:52 | |
It's delivering a very powerful magnetic pulse | 0:03:52 | 0:03:54 | |
for a brief fraction of a second | 0:03:54 | 0:03:56 | |
but why is it disrupting Vince's ability to speak? | 0:03:56 | 0:04:00 | |
I'm going to give you a clue with the next demonstration. | 0:04:00 | 0:04:02 | |
Have a look at this old television over here. | 0:04:02 | 0:04:05 | |
I'm going to need a magnet. | 0:04:05 | 0:04:07 | |
You can see the image on the television is perfectly normal | 0:04:08 | 0:04:11 | |
but look what happens when I bring a magnet close to it. | 0:04:11 | 0:04:14 | |
You can see the image is being distorted by the magnet. | 0:04:18 | 0:04:22 | |
Now, why is this? | 0:04:22 | 0:04:24 | |
Well, remarkably, the answer comes from none other | 0:04:24 | 0:04:27 | |
than the founder of the Royal Institution Christmas Lectures, | 0:04:27 | 0:04:30 | |
Michael Faraday, because Faraday discovered over 150 years ago | 0:04:30 | 0:04:33 | |
and often demonstrated in this very theatre | 0:04:33 | 0:04:36 | |
that there's a relationship between magnets and electrical fields. | 0:04:36 | 0:04:41 | |
The image on the television is produced by an electrified beam | 0:04:41 | 0:04:45 | |
so that when I bring a magnet close to it, | 0:04:45 | 0:04:47 | |
it's distorting the path of that beam | 0:04:47 | 0:04:49 | |
and that's why the image is being distorted. | 0:04:49 | 0:04:52 | |
So let's put these pieces of information together. | 0:04:52 | 0:04:55 | |
A magnet can disrupt an electrical field. | 0:04:55 | 0:04:57 | |
We know the magnet is disrupting Vince's ability to speak | 0:04:57 | 0:05:00 | |
which is a product of his brain so we can conclude that the brain | 0:05:00 | 0:05:05 | |
must be using some form of electrical communication to make you speak. | 0:05:05 | 0:05:09 | |
-Is that roughly correct, Vince? -True, yeah. -OK, Vince. | 0:05:09 | 0:05:12 | |
If I put a magnet next to my head, | 0:05:12 | 0:05:14 | |
it doesn't seem to disrupt any of my ability to speak, so why is that? | 0:05:14 | 0:05:19 | |
That's because the field you've got next to your head is static. | 0:05:19 | 0:05:23 | |
Even though you're moving at about, it's moving very slowly. | 0:05:23 | 0:05:26 | |
To create an electric field that disturbs brain cells, it's got to move very, very rapidly. | 0:05:26 | 0:05:31 | |
Every one of those clicks you hear is 1/10000 of a millisecond | 0:05:31 | 0:05:35 | |
so the field has to change very, very quickly | 0:05:35 | 0:05:38 | |
to create any electricity in the brain. | 0:05:38 | 0:05:41 | |
Would you like me to do some more disruption of Vince's brain? | 0:05:41 | 0:05:44 | |
-AUDIENCE: -Yes. -Vince, I'm sorry, | 0:05:44 | 0:05:46 | |
but we're going to put you through some more. OK, so, what else shall we try? | 0:05:46 | 0:05:51 | |
How about some motor control? | 0:05:51 | 0:05:53 | |
We could do that. We could try left and right-handed. | 0:05:53 | 0:05:56 | |
Can we try just affecting your right hand, would that be OK? | 0:05:56 | 0:06:00 | |
Right, so I'm going to take my magnet. Is it fully charged up again? | 0:06:00 | 0:06:03 | |
-It is. -I'll touch my nose a few times. | 0:06:03 | 0:06:07 | |
Let's see how accurate it you are when I place it up here. | 0:06:07 | 0:06:10 | |
-Is that the correct area? -Mhm. | 0:06:10 | 0:06:12 | |
ELECTRICAL CLICKING | 0:06:12 | 0:06:15 | |
AUDIENCE LAUGHS | 0:06:15 | 0:06:16 | |
Vince, tell the audience what that feels like? | 0:06:16 | 0:06:20 | |
It's actually quite painless but I've lost control of my muscles. | 0:06:20 | 0:06:24 | |
I've lost control of my ability to locate my hand in space. | 0:06:24 | 0:06:30 | |
-It's a very, very weird sensation. -Can we do one last example? | 0:06:30 | 0:06:33 | |
Can you, um...can you clap for us? | 0:06:33 | 0:06:35 | |
I'm just going to stick the magnet here, here we go. | 0:06:35 | 0:06:39 | |
You ready? Start clapping, please. | 0:06:39 | 0:06:41 | |
ELECTRICAL CLICKING | 0:06:42 | 0:06:43 | |
AUDIENCE LAUGHS | 0:06:43 | 0:06:44 | |
OK, I think we've put you through enough, Vince. | 0:06:44 | 0:06:47 | |
Before you go, tell us, please. | 0:06:47 | 0:06:50 | |
We've seen how a magnet can disrupt normal function, | 0:06:50 | 0:06:53 | |
but does it have any application? | 0:06:53 | 0:06:54 | |
It does. What we've done has been very dramatic. | 0:06:54 | 0:06:57 | |
We've been using very high magnetic fields to influence the brain | 0:06:57 | 0:07:00 | |
so we can see that it does affect the brain but if we use lower fields | 0:07:00 | 0:07:03 | |
and stimulate specific areas of the brain, we can work on treating | 0:07:03 | 0:07:07 | |
things like depression, or modelling brain disorders | 0:07:07 | 0:07:11 | |
or modelling stroke in real research, | 0:07:11 | 0:07:13 | |
so it's got lots and lots of applications. | 0:07:13 | 0:07:15 | |
Vince, that's been absolutely fascinating. | 0:07:15 | 0:07:17 | |
Would everyone give Vince a round of applause. | 0:07:17 | 0:07:20 | |
APPLAUSE | 0:07:20 | 0:07:22 | |
Do you realise we've just proved that the brain | 0:07:32 | 0:07:35 | |
is an electrical system, and I think that's pretty cool. | 0:07:35 | 0:07:38 | |
Not only do magnets disrupt brain function | 0:07:38 | 0:07:41 | |
but we can use magnets to look at the workings of the brain. | 0:07:41 | 0:07:44 | |
But to do so you have to have a very powerful magnet. | 0:07:44 | 0:07:47 | |
And we happen to have access to one not here in London | 0:07:47 | 0:07:50 | |
but up in Cheltenham where we've set up a live link. | 0:07:50 | 0:07:54 | |
We recorded this earlier. | 0:07:54 | 0:07:56 | |
Hello, I'm Dr Thalia Gjersoe | 0:07:56 | 0:07:57 | |
and I'm here at the MRI scanner so you can read my mind. | 0:07:57 | 0:08:01 | |
I'm here with Iain Lyburn who's going to take us through it. | 0:08:01 | 0:08:06 | |
Welcome to the Cheltenham Imaging Centre. | 0:08:06 | 0:08:08 | |
It's run by the Cobalt Appeal Fund | 0:08:08 | 0:08:11 | |
and houses imaging for PET and MRI | 0:08:11 | 0:08:14 | |
and today we're going to have an MRI scan looking at your brain, seeing how it works. | 0:08:14 | 0:08:18 | |
What I'd like to do is show you the scanner first of all. | 0:08:18 | 0:08:21 | |
-Have you seen it before? -No, I haven't. -Shall we've a look inside? -OK. | 0:08:21 | 0:08:25 | |
It's got a big metal door because it's housed in a big metal cage. | 0:08:28 | 0:08:32 | |
This is the scanner. | 0:08:32 | 0:08:33 | |
You'll be going in with your head in the scanner | 0:08:33 | 0:08:36 | |
and it's got a very strong magnetic field which is part of the way it works. | 0:08:36 | 0:08:40 | |
Karen's going to show us how strong the magnet is. | 0:08:40 | 0:08:43 | |
-She's actually got... -I've got a spanner on the end of a bit of rope. | 0:08:43 | 0:08:47 | |
You can see how powerful it is. So that's how strong it is. | 0:08:55 | 0:08:59 | |
Quite impressive that, actually, isn't it? | 0:09:00 | 0:09:02 | |
-Wow. Iain, can you hear me? -Yes, hi, good evening. | 0:09:02 | 0:09:06 | |
We've just seen this magnet of yours. | 0:09:06 | 0:09:09 | |
It's extraordinarily powerful. How powerful is it? | 0:09:09 | 0:09:12 | |
30,000 times as strong as the magnetic field of the Earth. | 0:09:12 | 0:09:15 | |
That sounds dangerous to me. Why doesn't it affect the human brain | 0:09:15 | 0:09:19 | |
when you put someone in a scanner? | 0:09:19 | 0:09:21 | |
Well, the magnet's actually fixed. | 0:09:21 | 0:09:23 | |
It doesn't move, there's no movement, | 0:09:23 | 0:09:25 | |
so it's safe to go in and use for imaging. | 0:09:25 | 0:09:28 | |
So it's not like the TMS. It's a static magnetic field. | 0:09:29 | 0:09:33 | |
-Is that correct? -It's a static magnetic field, so it's safe. -OK. | 0:09:33 | 0:09:37 | |
-Thalia, can you hear me? -Yes, I can, Bruce. Hello. | 0:09:37 | 0:09:40 | |
I wouldn't go into that machine with anything magnetic. | 0:09:40 | 0:09:43 | |
Have you got something small that you can put in your hand? | 0:09:43 | 0:09:46 | |
-I do. I've got a walnut. -You've got a walnut? All right. | 0:09:46 | 0:09:50 | |
Well, I want you to take the walnut into the scanner, OK, | 0:09:50 | 0:09:54 | |
and don't tell us which hand you're going to put it in | 0:09:54 | 0:09:56 | |
because were we're going to do a bit of mind reading, I think. | 0:09:56 | 0:10:00 | |
We'll be seeing a bit more of you later on. Or, should I say, we'll be seeing more of your brain. | 0:10:00 | 0:10:04 | |
For the moment, though, | 0:10:04 | 0:10:06 | |
can we give a warm round of applause to Thalia and Professor Iain Lyburn. | 0:10:06 | 0:10:10 | |
APPLAUSE | 0:10:10 | 0:10:14 | |
So all brains work by electrical signalling | 0:10:16 | 0:10:19 | |
and all brains are very similar but they can also be quite different, in some ways. | 0:10:19 | 0:10:23 | |
Take a look at all of these animal brains. | 0:10:23 | 0:10:26 | |
Take a guess at which brain you think this animal belongs to. | 0:10:26 | 0:10:29 | |
I'm going to give you a pound coin so you can estimate the size. | 0:10:29 | 0:10:32 | |
-Now, what animal do you think that might be? Shout it out. -Spider! | 0:10:32 | 0:10:36 | |
A spider? | 0:10:36 | 0:10:37 | |
-No, it's not a spider. Can we have another example? -Mouse! | 0:10:37 | 0:10:40 | |
Mouse? Who said mouse? Hands up. You're correct. It's a mouse. | 0:10:40 | 0:10:45 | |
OK, what about this creature here? | 0:10:45 | 0:10:46 | |
Rat. | 0:10:46 | 0:10:47 | |
Did someone say rat? | 0:10:47 | 0:10:49 | |
AUDIENCE CALL OUT | 0:10:49 | 0:10:53 | |
It's a rat's brain. What about this brain here? | 0:10:53 | 0:10:56 | |
AUDIENCE CALL OUT | 0:10:56 | 0:11:00 | |
It's a...it's a chicken. Believe it or not, that's a chicken's brain. | 0:11:00 | 0:11:04 | |
And what about this one here? | 0:11:04 | 0:11:06 | |
AUDIENCE CALL OUT | 0:11:06 | 0:11:08 | |
A tortoise? No. No. | 0:11:08 | 0:11:10 | |
AUDIENCE CALL OUT | 0:11:10 | 0:11:11 | |
It's a cat's brain. And here we have... a dog. | 0:11:11 | 0:11:16 | |
And finally this one. What's this one belong to? | 0:11:17 | 0:11:20 | |
AUDIENCE CALL OUT | 0:11:20 | 0:11:21 | |
A horse. Who said a horse? | 0:11:21 | 0:11:23 | |
Hands up if you said horse. | 0:11:23 | 0:11:25 | |
Let's consider the horse for a moment. | 0:11:25 | 0:11:27 | |
It's a very large animal, isn't it? A horse is on average three times bigger than a human | 0:11:27 | 0:11:31 | |
but look at the horse's brain in comparison to the human brain. | 0:11:31 | 0:11:35 | |
Let me take it around to show you. | 0:11:35 | 0:11:37 | |
Even though a horse is much larger than a human, | 0:11:38 | 0:11:40 | |
the brain is actually smaller | 0:11:40 | 0:11:43 | |
so this shows you the size of the body size | 0:11:43 | 0:11:45 | |
doesn't predict the size of the brain. | 0:11:45 | 0:11:47 | |
In fact, if you think about the size of a human body on average, | 0:11:47 | 0:11:51 | |
our brain is seven times larger than you would ever imagine. | 0:11:51 | 0:11:55 | |
So, who would like to hold a human brain? | 0:11:55 | 0:11:59 | |
That's an awful lot of you. | 0:11:59 | 0:12:01 | |
Unfortunately, we can't let you hold the human brain | 0:12:01 | 0:12:03 | |
but I just happen to have one which is just as good, | 0:12:03 | 0:12:06 | |
made out of synthetic plastic over here. | 0:12:06 | 0:12:08 | |
It's a very good copy. | 0:12:12 | 0:12:13 | |
It's the same shape, it's the same size and it's the same weight. | 0:12:13 | 0:12:18 | |
So, would you like to hold the human brain? | 0:12:18 | 0:12:20 | |
Who wants to halt the human brain. You do? Put your hands out. | 0:12:21 | 0:12:24 | |
-What's the first thing you notice about it? -It's quite heavy. | 0:12:26 | 0:12:29 | |
It extraordinarily heavy, isn't it? It's about one half pounds. | 0:12:29 | 0:12:33 | |
You can pass it along. | 0:12:33 | 0:12:34 | |
One and a half kilos, I should say. OK. | 0:12:34 | 0:12:36 | |
It's really quite heavy. | 0:12:38 | 0:12:40 | |
What else is it? What else do you notice about it? | 0:12:40 | 0:12:42 | |
Let me tell you. | 0:12:42 | 0:12:44 | |
Can I have my brain back? Thank you. | 0:12:44 | 0:12:46 | |
The brain, as you can see, | 0:12:47 | 0:12:49 | |
is made up of two halves and each half is called a hemisphere. | 0:12:49 | 0:12:53 | |
The interesting thing about the hemisphere is it controls | 0:12:53 | 0:12:56 | |
the opposite side of the body, so if you remember | 0:12:56 | 0:12:59 | |
when we were stimulating Vince's brain | 0:12:59 | 0:13:01 | |
with the trans-magnetic stimulator, | 0:13:01 | 0:13:03 | |
when I was activating his left side of the brain, | 0:13:03 | 0:13:06 | |
it was his right hand which was being affected. | 0:13:06 | 0:13:10 | |
Now, we don't really know why the brain is organised like that. | 0:13:10 | 0:13:13 | |
It's a little bit of a mystery. | 0:13:13 | 0:13:15 | |
In fact, you probably wouldn't be aware | 0:13:15 | 0:13:17 | |
unless you've got some damage on the opposite side and you noticed the behaviour was affected. | 0:13:17 | 0:13:22 | |
The other thing about the brain which I think is quite fascinating | 0:13:22 | 0:13:26 | |
is all these folds and creases | 0:13:26 | 0:13:27 | |
because all brains have this to some extent | 0:13:27 | 0:13:30 | |
but if you look at the example of the mouse brain or the rat brain, | 0:13:30 | 0:13:34 | |
they're really quite smooth. | 0:13:34 | 0:13:36 | |
In the human, these folds and creases are quite pronounced | 0:13:36 | 0:13:40 | |
so why is that? | 0:13:40 | 0:13:41 | |
To get an answer for that, you really have to zoom in | 0:13:41 | 0:13:44 | |
to the building blocks of the brain | 0:13:44 | 0:13:46 | |
to a special kind of cell called a neuron and here we have | 0:13:46 | 0:13:49 | |
the image of a neuron and as you can see | 0:13:49 | 0:13:52 | |
it looks like a kind of strange alien creature from outer space | 0:13:52 | 0:13:55 | |
and there's a lot of them. | 0:13:55 | 0:13:57 | |
There are about 100 billion neurons in the average brain. | 0:13:57 | 0:14:00 | |
And all these tentacles are dendrites | 0:14:00 | 0:14:03 | |
and this is the way neurons are communicating with each other, | 0:14:03 | 0:14:06 | |
by sending electrical impulses. | 0:14:06 | 0:14:09 | |
Each neuron typically has one very thick connecting fibre | 0:14:09 | 0:14:12 | |
called the axon and it's the axon that sends out information | 0:14:12 | 0:14:15 | |
to connect up with all the others. | 0:14:15 | 0:14:18 | |
Now, it turns out that the neurons | 0:14:18 | 0:14:21 | |
and the connections which are related to those things we consider | 0:14:21 | 0:14:24 | |
intelligence and being clever, they're not throughout the brain. | 0:14:24 | 0:14:28 | |
They're concentrated in just the outer layer of the brain, | 0:14:28 | 0:14:31 | |
a layer that's only 3-4 millimetres thick. | 0:14:31 | 0:14:35 | |
We call this the cortex. | 0:14:35 | 0:14:36 | |
The cortex comes from the Latin word for bark. | 0:14:36 | 0:14:40 | |
So it's this outer layer with all these connections which make us | 0:14:40 | 0:14:44 | |
very clever and flexible in our thinking. | 0:14:44 | 0:14:47 | |
So it's not so much the size of the brain that's important. | 0:14:47 | 0:14:49 | |
Rather, it's the surface area of the cortex | 0:14:49 | 0:14:52 | |
and how big that is that allows for all these connections. | 0:14:52 | 0:14:56 | |
If you take the human brain and flatten it out, | 0:14:56 | 0:14:59 | |
it would have this degree of surface area. | 0:14:59 | 0:15:01 | |
Would you hold my brain for a moment? | 0:15:01 | 0:15:03 | |
OK, so this is how big the human cortex is if you flatten it out. | 0:15:03 | 0:15:07 | |
That's a very big area, so how do you get all that inside a normal head? | 0:15:07 | 0:15:13 | |
Well, here's nature's solution. | 0:15:13 | 0:15:15 | |
It's all folded up. | 0:15:16 | 0:15:17 | |
So nature has come up with an answer | 0:15:17 | 0:15:20 | |
for, basically, an engineering problem. | 0:15:20 | 0:15:23 | |
Thank you very much. | 0:15:23 | 0:15:24 | |
Now, if it wasn't all folded up like that, | 0:15:26 | 0:15:30 | |
then your head would have to be half as big again, which is not a good look | 0:15:30 | 0:15:33 | |
and, for any mothers watching, it's bad enough giving birth | 0:15:33 | 0:15:36 | |
to a baby of a normal sized head without it being any larger. | 0:15:36 | 0:15:40 | |
OK, so let's now consider some other animals. Look at these little guys. | 0:15:40 | 0:15:45 | |
They're quite exotic, aren't they? | 0:15:47 | 0:15:49 | |
Does anyone know what they are? They're jellyfish, that's right. | 0:15:49 | 0:15:53 | |
They're Australian Blubber Jellyfish | 0:15:53 | 0:15:55 | |
and you can see them moving around in the pool. | 0:15:55 | 0:15:59 | |
So what's so special about the brain of a jellyfish? | 0:15:59 | 0:16:02 | |
Would anyone like to answer? | 0:16:02 | 0:16:03 | |
-Sir? -Is it transparent? -That's a good answer. | 0:16:03 | 0:16:06 | |
-Anything else? Yes? -It doesn't have one? | 0:16:06 | 0:16:10 | |
It doesn't have one. Well done. | 0:16:10 | 0:16:12 | |
A trick question. They do have a central nervous system | 0:16:12 | 0:16:15 | |
but they don't really have a brain as such. | 0:16:15 | 0:16:18 | |
So if jellyfish don't have brains, | 0:16:18 | 0:16:20 | |
then why do all these other animals have brains? | 0:16:20 | 0:16:23 | |
Why do you think we have a brain in the first place? | 0:16:23 | 0:16:26 | |
Who would like to answer? Yes. | 0:16:26 | 0:16:28 | |
Because otherwise we wouldn't be alive? | 0:16:28 | 0:16:30 | |
Otherwise we wouldn't be alive, that's good. Any more answers? | 0:16:30 | 0:16:33 | |
-Yes? -Memory. | 0:16:33 | 0:16:35 | |
These are all great answers but the basic answer for all the animals | 0:16:35 | 0:16:38 | |
which have brains is that we use brains to navigate around the world. | 0:16:38 | 0:16:43 | |
The jellyfish can move | 0:16:43 | 0:16:44 | |
but it's not keeping track of where it's going and jellyfish | 0:16:44 | 0:16:47 | |
tend to go with the ebb and flow of the tides whereas animals that have | 0:16:47 | 0:16:51 | |
brains are using them to navigate their world, to find food, | 0:16:51 | 0:16:55 | |
to seek mates, to avoid predators | 0:16:55 | 0:16:56 | |
and to keep track of where they're going | 0:16:56 | 0:16:59 | |
in order to plan their movements in the world. | 0:16:59 | 0:17:01 | |
So brains are for figuring out and predicting what's going to go next. | 0:17:01 | 0:17:05 | |
If you think about it, an animal, or an animal like us, | 0:17:05 | 0:17:08 | |
is really a kind of complex mobile moving factory made up of many subdivisions, | 0:17:08 | 0:17:13 | |
different processing plants, recycling centres | 0:17:13 | 0:17:16 | |
and movement machinery, and that all has to be coordinated. | 0:17:16 | 0:17:19 | |
If it wasn't, we'd fall apart | 0:17:19 | 0:17:22 | |
so brains are really for controlling all these different activities. | 0:17:22 | 0:17:26 | |
Now some of these activities are fairly automated. | 0:17:26 | 0:17:29 | |
For example, breathing and hearts are controlled by the brainstem | 0:17:29 | 0:17:32 | |
which is below the cortex, so it doesn't require a lot of consciousness. | 0:17:32 | 0:17:36 | |
And other things like your movements that you've learnt well, you don't have to think about them. | 0:17:36 | 0:17:41 | |
Even walking. You know where you're going and you can plan that, but coordinating the movements, | 0:17:41 | 0:17:46 | |
you don't have to think about that. | 0:17:46 | 0:17:48 | |
And that's controlled by the cerebellum at the bottom here. | 0:17:48 | 0:17:51 | |
So whether they're automatic or controlled, | 0:17:51 | 0:17:53 | |
the whole point is they still need to be coordinated by a system | 0:17:53 | 0:17:56 | |
and that's what the cortex does, sitting up here. | 0:17:56 | 0:17:59 | |
So the information is flooding up into the brain | 0:17:59 | 0:18:01 | |
through the central nervous system. | 0:18:01 | 0:18:03 | |
The information from the most extreme parts, for example the arms | 0:18:03 | 0:18:07 | |
or even the legs, they form part of the peripheral nervous system. | 0:18:07 | 0:18:12 | |
So how fast does a nerve impulse travel? | 0:18:12 | 0:18:14 | |
Well, we're going to try a little experiment. We're going to measure the speed of a nerve impulse | 0:18:14 | 0:18:18 | |
travelling the length of one arm and I'm going to need some volunteers. | 0:18:18 | 0:18:22 | |
In fact, I'm going to need all of Row E, so stand up, row E. | 0:18:22 | 0:18:27 | |
Big round of applause. | 0:18:27 | 0:18:29 | |
APPLAUSE | 0:18:29 | 0:18:32 | |
-What's your name, sir? -My name's Omar. -Omar? -Yep. | 0:18:36 | 0:18:39 | |
-OK, Omar, and who do we have at the end? -Tim. -Hello, Tim. | 0:18:39 | 0:18:43 | |
Omar, what I'm going to do is I'm going to grip your left shoulder with my right hand | 0:18:43 | 0:18:47 | |
and with your right hand, you grip the left shoulder | 0:18:47 | 0:18:50 | |
and everyone copy everyone so you form a chain reaction. | 0:18:50 | 0:18:52 | |
OK. Are you all holding? Right. | 0:18:52 | 0:18:55 | |
What I'm going to do is I'm going to squeeze your shoulder gently and everyone do it gently. | 0:18:55 | 0:19:00 | |
When you feel your shoulder being squeezed, and not before, | 0:19:00 | 0:19:03 | |
you squeeze your neighbour's shoulder, so it's going to pass the entire length of Row E. | 0:19:03 | 0:19:07 | |
OK? And Tim at the end, when you feel your shoulder being squeezed, | 0:19:07 | 0:19:10 | |
you shout stop because we're going to measure the speed, | 0:19:10 | 0:19:14 | |
the time it takes for that response to travel the full length of Row E. | 0:19:14 | 0:19:18 | |
You got it? | 0:19:18 | 0:19:19 | |
So let's go. | 0:19:19 | 0:19:22 | |
-Stop. -OK, that's pretty good. That's 3.10 seconds. | 0:19:24 | 0:19:28 | |
Let's see if you can get a bit faster. All right, ready again? | 0:19:28 | 0:19:32 | |
-Stop. -OK, that's just under three seconds. That's pretty good. You are getting better with practise. | 0:19:36 | 0:19:41 | |
Now, this time I don't want you to grip the shoulder. | 0:19:41 | 0:19:44 | |
I want you to hold hands. You should be even faster now, shouldn't you? | 0:19:44 | 0:19:48 | |
Squeeze your neighbour's hand when you feel your left hand is squeezed | 0:19:48 | 0:19:51 | |
and, again, Tim, you shout stop when you feel that. | 0:19:51 | 0:19:54 | |
OK, ready? | 0:19:54 | 0:19:55 | |
Stop. | 0:19:59 | 0:20:00 | |
That's three seconds, almost a full second longer. | 0:20:00 | 0:20:05 | |
Now, why does it take longer for the nerve impulse to travel the full distance? | 0:20:05 | 0:20:09 | |
If you think about it, the first time we did it | 0:20:09 | 0:20:11 | |
it's only travelling the length of one arm. | 0:20:11 | 0:20:14 | |
But when we're holding hands, | 0:20:14 | 0:20:15 | |
it has to travel the length of one arm plus an extra arm to the person next to you. | 0:20:15 | 0:20:20 | |
An arm is almost a metre long, isn't it? | 0:20:20 | 0:20:23 | |
And with 15 arms, that's an extra 15 metres it has to travel | 0:20:23 | 0:20:27 | |
in just under about a second, so it's somewhere between 10 and 15 metres per second, | 0:20:27 | 0:20:31 | |
which is about right for that kind of nerve impulse. | 0:20:31 | 0:20:33 | |
So, a big round of applause for row E. | 0:20:33 | 0:20:35 | |
APPLAUSE | 0:20:35 | 0:20:39 | |
So, we were estimating the speed of a nerve impulse in the arm, | 0:20:41 | 0:20:44 | |
and it's usually roundabout that kind of speed, | 0:20:44 | 0:20:47 | |
and that's usually a lot slower than people imagine, | 0:20:47 | 0:20:50 | |
because when you think about nerve impulses we often assume | 0:20:50 | 0:20:53 | |
they must be almost as fast as electricity, | 0:20:53 | 0:20:56 | |
because it seems like it is an electrical impulse. | 0:20:56 | 0:20:58 | |
But, in fact, electricity travels about three million times faster than a nerve impulse. | 0:20:58 | 0:21:04 | |
So, we've been using these sorts of experiments to try | 0:21:04 | 0:21:07 | |
and estimate how the brain is working, | 0:21:07 | 0:21:10 | |
but can you ever really measure directly nerve activity? | 0:21:10 | 0:21:13 | |
Remarkably, you can if you're an expert and you know what you're doing, | 0:21:13 | 0:21:17 | |
and you happen to have a very thin wire. | 0:21:17 | 0:21:19 | |
So, would you give a warm welcome to two experts from Newcastle, | 0:21:19 | 0:21:22 | |
Dr Claire Rind and Dr Peter Simmons. | 0:21:22 | 0:21:25 | |
APPLAUSE | 0:21:25 | 0:21:29 | |
So, Claire, I believe you've had some interesting travelling | 0:21:35 | 0:21:39 | |
companions with you, is that right? | 0:21:39 | 0:21:41 | |
We have, we've come down on the train with a box full of locusts. | 0:21:41 | 0:21:44 | |
Oh, right. So these are live locusts? | 0:21:44 | 0:21:48 | |
Yes, they're all munching on the grass, | 0:21:48 | 0:21:51 | |
there's about six of them in there, varying sizes. | 0:21:51 | 0:21:54 | |
So he's gently being placed on his back, is that right? | 0:21:54 | 0:21:57 | |
Yes, in a little bed of Plasticine - it's actually a she - | 0:21:57 | 0:22:02 | |
lying on her back in a bed of Plasticine | 0:22:02 | 0:22:05 | |
and we've restrained the animal with little loops of Plasticine, | 0:22:05 | 0:22:10 | |
and Peter is putting a very fine wire into its chest. | 0:22:10 | 0:22:15 | |
The wire is rather like an acupuncture wire, very fine, | 0:22:15 | 0:22:19 | |
-just a small diameter wire. -So it doesn't hurt the locust at all? | 0:22:19 | 0:22:23 | |
-No, not at all. -That's amazing. | 0:22:23 | 0:22:25 | |
Whilst Peter is setting up, because this is a very delicate procedure, | 0:22:25 | 0:22:29 | |
let me tell you a little bit about the locust. | 0:22:29 | 0:22:32 | |
The locust is really a giant kind of grasshopper, and it has this | 0:22:32 | 0:22:36 | |
very simple nervous system for avoiding bumping into things. | 0:22:36 | 0:22:40 | |
The reason it needs to do this is | 0:22:40 | 0:22:42 | |
because when they get large in numbers they can become swarms, | 0:22:42 | 0:22:46 | |
which are travelling in their vast numbers, | 0:22:46 | 0:22:48 | |
and there's literally millions of them, | 0:22:48 | 0:22:50 | |
and they can fly without bumping into each other. | 0:22:50 | 0:22:53 | |
Swarms can be a real problem, because when they land on a crop | 0:22:53 | 0:22:57 | |
they'll just ravish a crop and eat it within minutes. | 0:22:57 | 0:23:00 | |
So, they are usually a pest to humans, | 0:23:00 | 0:23:02 | |
but they've also been very helpful because we can measure their brain activity without hurting them. | 0:23:02 | 0:23:08 | |
This is what you've been doing in your research, is that right? | 0:23:08 | 0:23:11 | |
Yes, we've been looking at particular nerve cells | 0:23:11 | 0:23:15 | |
within its nervous system and using this recording equipment | 0:23:15 | 0:23:19 | |
to record electrical activity that the nerve cells make. | 0:23:19 | 0:23:23 | |
In fact, the noise that you'll hear eventually is from | 0:23:23 | 0:23:27 | |
a single nerve cell within the locust's nerve system. | 0:23:27 | 0:23:31 | |
It's a very important neuron, | 0:23:31 | 0:23:33 | |
one of the biggest in the body of the locust, | 0:23:33 | 0:23:38 | |
and it communicates down to the wings | 0:23:38 | 0:23:40 | |
and can actually shut off the flight cycle | 0:23:40 | 0:23:43 | |
so that the locust will make a dive and avoid a predator | 0:23:43 | 0:23:47 | |
or adjust its flight to avoid another member of the swarm. | 0:23:47 | 0:23:51 | |
OK, so, Peter, are we ready? | 0:23:51 | 0:23:53 | |
We're ready, I think she's ready, as well. | 0:23:53 | 0:23:56 | |
I couldn't tell the difference, but I presume they're larger, the females? | 0:23:56 | 0:24:00 | |
The female's larger, yes. | 0:24:00 | 0:24:02 | |
OK, so which part of the visual field are we going to be recording from? | 0:24:02 | 0:24:06 | |
We're recording from the right side of the locust, | 0:24:06 | 0:24:09 | |
but it's the eye that is looking towards the left, | 0:24:09 | 0:24:13 | |
she's on her back, so she's watching you. | 0:24:13 | 0:24:16 | |
-She's watching me now? -She's watching you now. | 0:24:16 | 0:24:18 | |
-Right, so we're going to listen in to her responding to me, is that correct? -Yes. | 0:24:18 | 0:24:23 | |
Let's have some silence, listen very carefully, | 0:24:23 | 0:24:26 | |
what you'll be hearing is the activity of the neurons. | 0:24:26 | 0:24:30 | |
STATIC CRACKLING IN TIME WITH HAND MOVEMENTS | 0:24:30 | 0:24:35 | |
Can you hear that? | 0:24:35 | 0:24:36 | |
Do you realise you are listening to the brain of a locust? | 0:24:39 | 0:24:44 | |
We know it's from that side because if I come from the other side... | 0:24:44 | 0:24:50 | |
..you don't get the effect. | 0:24:53 | 0:24:54 | |
Whereas, actually, I think she's paying quite a lot of attention to me now, isn't she? | 0:24:54 | 0:25:00 | |
That is absolutely fascinating. Shall we try with this? | 0:25:02 | 0:25:06 | |
This represents another large locust flying in the swarm towards it. | 0:25:06 | 0:25:10 | |
RYTHMIC CRACKLING | 0:25:10 | 0:25:14 | |
That's great. | 0:25:14 | 0:25:16 | |
So, tell me, Claire, with this research what have you been able to do? | 0:25:16 | 0:25:19 | |
Does it have any application for humans at all? | 0:25:19 | 0:25:22 | |
It's a fascinating circuit the locust has and we've built | 0:25:22 | 0:25:25 | |
an artificial circuit that we've been able to put into a sensor | 0:25:25 | 0:25:31 | |
that is used for collision avoidance in cars, | 0:25:31 | 0:25:34 | |
so we're hoping in the future that the circuits based on the locust | 0:25:34 | 0:25:38 | |
will be able to help drivers avoid collisions in traffic. | 0:25:38 | 0:25:43 | |
So, the locust insect is helping humans to avoid pileups on the M1? | 0:25:43 | 0:25:47 | |
Eventually, that's what we think. | 0:25:47 | 0:25:49 | |
Well, I think that's very useful. | 0:25:49 | 0:25:51 | |
Can you release the locust to just show everything is fine with her? | 0:25:51 | 0:25:54 | |
Can we get a close-up of the locust, just to show you? | 0:25:56 | 0:25:59 | |
We can't let go because if she gets the chance she'll run away. | 0:25:59 | 0:26:02 | |
You can see there she's perfectly OK. | 0:26:02 | 0:26:05 | |
-And she bit me. -That's revenge, she's getting her own back, Peter. | 0:26:05 | 0:26:08 | |
Let's put her back with her friends and let them go. | 0:26:08 | 0:26:12 | |
Can we have a big round of applause for the locust... | 0:26:12 | 0:26:15 | |
APPLAUSE | 0:26:15 | 0:26:16 | |
...and Peter and Claire. Thank you so much for coming down. | 0:26:16 | 0:26:20 | |
That was fascinating, | 0:26:27 | 0:26:29 | |
but can we ever do the same thing for a human? | 0:26:29 | 0:26:31 | |
Well, we chose a volunteer earlier, and this is Billy. | 0:26:31 | 0:26:34 | |
He can't talk to us at the moment because we have him wired up. | 0:26:34 | 0:26:38 | |
We're not sticking an electrode in his brain, | 0:26:38 | 0:26:41 | |
rather we're recording from the outside, because it turns out | 0:26:41 | 0:26:45 | |
that, if you have lots of neurons firing, they generate enough | 0:26:45 | 0:26:48 | |
electrical activity that we can detect it with tiny electrodes. | 0:26:48 | 0:26:51 | |
Normally when scientists do this, they have lots of electrodes, | 0:26:51 | 0:26:55 | |
but for tonight's purposes we're just interested in the back of Billy's head, | 0:26:55 | 0:27:00 | |
because this is where his visual area is, | 0:27:00 | 0:27:02 | |
the visual cortex in the human. | 0:27:02 | 0:27:04 | |
So, as before, we saw the locust was looking at a human - me - | 0:27:04 | 0:27:08 | |
approaching the locust, this time we're presenting a locust | 0:27:08 | 0:27:11 | |
to a human to see how they respond. | 0:27:11 | 0:27:13 | |
And here we see this big pattern starting to build up. | 0:27:13 | 0:27:16 | |
This is the response of Billy's visual area. Thank you, Kate. | 0:27:16 | 0:27:21 | |
As you can see, as the locust was coming on it was responding, | 0:27:21 | 0:27:25 | |
so the picture of the locust was generating activity in his eyes, | 0:27:25 | 0:27:29 | |
then sending these impulses along the optic fibre | 0:27:29 | 0:27:31 | |
to the back of the brain where the visual processing area is, then responding to that. | 0:27:31 | 0:27:36 | |
That's the onset of the pattern, when the locust first appears, | 0:27:36 | 0:27:40 | |
and this is the rest of the brainwave, showing how he processes it. | 0:27:40 | 0:27:43 | |
So, Billy, it turns out that you do have a brain, | 0:27:43 | 0:27:45 | |
so thank you very much and a big round of applause to Kate and Billy. | 0:27:45 | 0:27:50 | |
APPLAUSE AND CHEERING | 0:27:50 | 0:27:53 | |
Animals might be all moving and interacting in the same environment, | 0:27:53 | 0:27:58 | |
like the locusts and humans, but their brains are very different, | 0:27:58 | 0:28:02 | |
and what they're experiencing must be different. | 0:28:02 | 0:28:05 | |
And even our own experience is often not what it seems. | 0:28:05 | 0:28:09 | |
So, consider vision again. | 0:28:09 | 0:28:11 | |
Most of us think that vision is rich and full of detail - | 0:28:11 | 0:28:15 | |
in fact, a lot of us think it's almost like a camera, but is it really? | 0:28:15 | 0:28:18 | |
Let's test that idea out. Joe, would you come in here? | 0:28:18 | 0:28:22 | |
Joe's got a camera on his shoulder and he's taking the image | 0:28:22 | 0:28:26 | |
and you can see that the image is projected above me | 0:28:26 | 0:28:29 | |
and it's nice and rich and full of detail. | 0:28:29 | 0:28:31 | |
This is what we think vision is really like, | 0:28:31 | 0:28:34 | |
but, actually, human vision isn't like that at all, | 0:28:34 | 0:28:37 | |
because we know from the studies using these techniques | 0:28:37 | 0:28:40 | |
you're only ever processing the centre part of your vision, | 0:28:40 | 0:28:43 | |
and in fact it's about the size of your thumb held at arm's length. | 0:28:43 | 0:28:46 | |
So, can we make the camera appear like human vision? | 0:28:46 | 0:28:50 | |
Now you can see it's all blurred at the edge | 0:28:50 | 0:28:52 | |
and it's only the central part of the field which is clear and detailed. | 0:28:52 | 0:28:56 | |
That's a bit strange, because that's not the way you experience vision, do you? | 0:28:56 | 0:29:01 | |
You see it as full and complex. | 0:29:01 | 0:29:03 | |
So, why is that? Well, let me show you. | 0:29:03 | 0:29:07 | |
If I move a bit closer... | 0:29:07 | 0:29:09 | |
the way that it seems more detailed is, of course, | 0:29:09 | 0:29:12 | |
I simply move my eyes around. | 0:29:12 | 0:29:15 | |
And I'm moving them quite rapidly, about four or five times per second. | 0:29:15 | 0:29:20 | |
These are called saccades. | 0:29:20 | 0:29:21 | |
This is how the brain builds up a picture of complexity, | 0:29:21 | 0:29:24 | |
because you're sampling the world | 0:29:24 | 0:29:26 | |
then storing that information, and the brain is remembering it, | 0:29:26 | 0:29:30 | |
and this is what makes the world seem much more complex. | 0:29:30 | 0:29:33 | |
There's a problem, though, | 0:29:33 | 0:29:35 | |
because if a camera was to move like human vision, | 0:29:35 | 0:29:38 | |
there'd be a real distortion, so let's take that away. | 0:29:38 | 0:29:41 | |
Joe, can you move your camera like an eye movement? | 0:29:41 | 0:29:44 | |
Let's see what that looks like. | 0:29:44 | 0:29:46 | |
Now, what's wrong with that? Any suggestions? Yes. | 0:29:55 | 0:29:59 | |
-AUDIENCE MEMBER: -It's kind of moving quite fast. | 0:29:59 | 0:30:01 | |
It's very jerky, isn't it? It's very blurred. | 0:30:01 | 0:30:04 | |
If that was your normal vision it'd make you very seasick, | 0:30:04 | 0:30:07 | |
so your brain does a very clever trick. | 0:30:07 | 0:30:10 | |
Every time you move your eyes it cuts out the visual information, | 0:30:10 | 0:30:14 | |
so you don't see all those jerky, smeared, blurred images. | 0:30:14 | 0:30:17 | |
So, Joe, can you simulate that, can you turn off the visual signal | 0:30:17 | 0:30:21 | |
every time you're moving the camera? | 0:30:21 | 0:30:23 | |
OK, your brain is literally cutting off all the visual information, in fact you can't see anything. | 0:30:29 | 0:30:35 | |
We know that's true, I'm going to prove it and I'll need a volunteer. | 0:30:35 | 0:30:39 | |
Let's see who we can choose. Do we have anyone? Young lady. | 0:30:39 | 0:30:42 | |
-What's your name? -Amy. | 0:30:42 | 0:30:44 | |
Amy, OK, would you hold the mirror like this, OK? | 0:30:44 | 0:30:47 | |
Josh, can you pick up Amy? Good. | 0:30:47 | 0:30:49 | |
Now, Amy, have a look at your left eye. | 0:30:49 | 0:30:52 | |
Now look at your right eye. | 0:30:52 | 0:30:54 | |
Swap backwards and forwards. | 0:30:54 | 0:30:56 | |
-Can you see your eyes moving? -No. | 0:30:56 | 0:31:00 | |
Can you see your eyes moving at all? | 0:31:01 | 0:31:04 | |
-Can anyone else see her eyes moving? -AUDIENCE: -Yes. | 0:31:04 | 0:31:06 | |
Amy, your eyes are moving, would you like me to prove it to you? | 0:31:06 | 0:31:10 | |
Have a look up there. | 0:31:10 | 0:31:12 | |
Ready? | 0:31:12 | 0:31:14 | |
LAUGHTER | 0:31:17 | 0:31:19 | |
It would seem like you're surprised, but don't worry, | 0:31:19 | 0:31:22 | |
you're perfectly normal, you can't see your own eyes moving at all. | 0:31:22 | 0:31:25 | |
Applause for Amy, please. | 0:31:25 | 0:31:28 | |
APPLAUSE | 0:31:28 | 0:31:31 | |
Now, you can try that all at home, actually. | 0:31:33 | 0:31:36 | |
If you're brushing your teeth, just look in the mirror | 0:31:36 | 0:31:39 | |
then focus on your left eye and shift to your right eye, | 0:31:39 | 0:31:42 | |
see if you can see your eyes moving, and you won't be able to, | 0:31:42 | 0:31:45 | |
because, no matter how you try, your brain is making you blind. | 0:31:45 | 0:31:48 | |
Effectively, if you add up all the gaps - you're moving your eyes all the time when you're awake - | 0:31:48 | 0:31:54 | |
you're blind for about two hours of the day, and you never even know that. Isn't that remarkable? | 0:31:54 | 0:31:59 | |
Clearly the mind has amazing tricks that keep the world looking | 0:31:59 | 0:32:03 | |
rich and full of detail and information. | 0:32:03 | 0:32:06 | |
So, what happens to all that information once you've detected it? | 0:32:06 | 0:32:09 | |
Ice creams! Get your ice creams here! Ice creams! | 0:32:09 | 0:32:12 | |
Ah, here's some rich information - an ice cream. Thank you very much. | 0:32:12 | 0:32:16 | |
So, consider an ice cream. It's full of lots of information. | 0:32:16 | 0:32:22 | |
It looks delicious, it smells delicious, I'm going to do this... | 0:32:22 | 0:32:27 | |
You can hear the crunch, it's cold, and it tastes very yummy, | 0:32:28 | 0:32:34 | |
but somehow my brain combines all these different sensations | 0:32:34 | 0:32:38 | |
into one experience a delicious ice cream. | 0:32:38 | 0:32:41 | |
How does it do that? | 0:32:41 | 0:32:42 | |
I'm going to show you by building a very simple brain in this auditorium. | 0:32:42 | 0:32:48 | |
OK, we had some helmets given out earlier, so pop your helmets on. | 0:32:48 | 0:32:52 | |
Those with the helmets, would you mind standing up? | 0:32:52 | 0:32:56 | |
these are our volunteers. | 0:32:56 | 0:32:58 | |
You're going to represent different groups of neurons. | 0:32:58 | 0:33:01 | |
Let's say this part of the brain is coding for shapes. | 0:33:01 | 0:33:05 | |
Sir, at the back, you code for anything which is round. | 0:33:05 | 0:33:08 | |
And you in the front code for anything which is long, like a pencil. | 0:33:08 | 0:33:11 | |
This part of the audience will represent the part of the brain | 0:33:11 | 0:33:15 | |
which codes for colour, so you're going to be green, | 0:33:15 | 0:33:18 | |
and you're going to respond to anything that's yellow. | 0:33:18 | 0:33:21 | |
And over here we have a part of the brain which codes for taste, | 0:33:21 | 0:33:24 | |
so you're getting information from the mouth, and you at the back, | 0:33:24 | 0:33:28 | |
you're going to be sweet and you're going to be salty. | 0:33:28 | 0:33:31 | |
Now hold-up these connections, because these are going to stand | 0:33:31 | 0:33:35 | |
for all the connections between the different regions of the brain. | 0:33:35 | 0:33:40 | |
Now press your buttons and let's see all the activity in the brain sending signals. | 0:33:40 | 0:33:44 | |
You can flash them, let's see a lot of random connections. | 0:33:44 | 0:33:47 | |
So here's our simple brain. How does a simple brain learn about objects? | 0:33:47 | 0:33:51 | |
Well, we're going to teach it to learn about fruit. | 0:33:51 | 0:33:54 | |
OK, so pop your lights off for a moment. | 0:33:54 | 0:33:58 | |
Now, imagine that you've never eaten a banana before. | 0:33:58 | 0:34:01 | |
So, let's have you responding, if your feature's present, hold down your button. | 0:34:01 | 0:34:05 | |
Let's see what that looks like. | 0:34:05 | 0:34:07 | |
So it's long, it's yellow, | 0:34:07 | 0:34:09 | |
and you pop it in your mouth and what does it taste like? Sweet. | 0:34:09 | 0:34:12 | |
Sweet. So that's the pattern for a banana. | 0:34:12 | 0:34:15 | |
All right, now everyone switch your lights on again, | 0:34:15 | 0:34:19 | |
communicating again, there it's talking to itself, and put them off. | 0:34:19 | 0:34:23 | |
Let's come across another fruit. | 0:34:23 | 0:34:26 | |
This time, it's round, hold it down... | 0:34:26 | 0:34:29 | |
it's green... | 0:34:29 | 0:34:31 | |
and you pop it into your mouth and it's sweet. | 0:34:31 | 0:34:34 | |
And every time you eat a banana, or a grape, | 0:34:36 | 0:34:39 | |
that pattern becomes stronger. | 0:34:39 | 0:34:41 | |
This is because the neurons that fire together are wiring together. | 0:34:41 | 0:34:45 | |
Now, you might notice how the banana and the grape | 0:34:45 | 0:34:50 | |
are activating the same part, which is the sweet centres. | 0:34:50 | 0:34:53 | |
That shows you the brain can reuse the same regions | 0:34:53 | 0:34:56 | |
to code for different objects. | 0:34:56 | 0:34:57 | |
So, what happens when you go to a new part of the world | 0:34:57 | 0:35:01 | |
and encounter new food you've never had before? | 0:35:01 | 0:35:04 | |
Turn your lights off for a moment. | 0:35:04 | 0:35:06 | |
Let's say you go to the Mediterranean | 0:35:06 | 0:35:08 | |
and you see this small, round, green thing. | 0:35:08 | 0:35:11 | |
So it's round, it's green, and your brain thinks, | 0:35:11 | 0:35:15 | |
"Well, it looks like a grape, so it's going to be sweet." | 0:35:15 | 0:35:18 | |
So, sweet, pop your light on. | 0:35:18 | 0:35:20 | |
But then when you pop it into your mouth... | 0:35:20 | 0:35:23 | |
Yuck! It's salty! | 0:35:23 | 0:35:26 | |
So, this is why you can be very surprised | 0:35:26 | 0:35:28 | |
when you encounter something new which seems so familiar. | 0:35:28 | 0:35:31 | |
That's why new foods can surprise you. | 0:35:31 | 0:35:35 | |
Let's consider our simple brain again. | 0:35:35 | 0:35:38 | |
If I show you this pattern... | 0:35:38 | 0:35:41 | |
Tell us, audience, what do you think that stands for, that pattern? | 0:35:41 | 0:35:45 | |
AUDIENCE: Banana. | 0:35:45 | 0:35:47 | |
It stands for banana, but it's not really a banana, is it? | 0:35:47 | 0:35:51 | |
It's just how the brain recreates the sensation of eating bananas. | 0:35:51 | 0:35:54 | |
It's what we call a representation, | 0:35:54 | 0:35:57 | |
because the brain is re-presenting the original experience. | 0:35:57 | 0:36:01 | |
Representations are really the language of the brain. | 0:36:01 | 0:36:04 | |
Now, I have given you a very simple demonstration with only a few groups of neurons, | 0:36:04 | 0:36:09 | |
just to give you an idea of different patterns, | 0:36:09 | 0:36:11 | |
but the brain is much more complex. | 0:36:11 | 0:36:13 | |
If this were a real brain, there'd be 100 billion neurons, | 0:36:13 | 0:36:17 | |
and you wouldn't just be holding a couple of connections, | 0:36:17 | 0:36:20 | |
because the neurons have up to 10,000 connections between them, | 0:36:20 | 0:36:24 | |
and if you add up all the connections end to end, | 0:36:24 | 0:36:26 | |
that stretches to 180,000 kilometres, | 0:36:26 | 0:36:30 | |
and that's long enough to stretch around the world four times. | 0:36:30 | 0:36:33 | |
That's rather mind blowing, isn't it? | 0:36:33 | 0:36:35 | |
Because it means your brain has the capacity to encode an almost | 0:36:35 | 0:36:38 | |
infinite number of patterns, which is why we say the human brain | 0:36:38 | 0:36:42 | |
is the most complex structure to be found in nature. | 0:36:42 | 0:36:45 | |
So, let's have a big round of applause for our small brain. | 0:36:45 | 0:36:49 | |
APPLAUSE | 0:36:49 | 0:36:53 | |
So, our world is full of rich experiences that are combined into these meaningful patterns, | 0:36:54 | 0:36:59 | |
and these representations reflect all the structure and order | 0:36:59 | 0:37:03 | |
that we encounter on a regular basis in our existence, in our lives. | 0:37:03 | 0:37:08 | |
So, for example, if I have this garbage lid, | 0:37:08 | 0:37:11 | |
you're processing this in different parts of your brain. | 0:37:11 | 0:37:14 | |
You have a areas which are processing the vision, | 0:37:14 | 0:37:17 | |
and if I drop it... | 0:37:17 | 0:37:19 | |
you have areas of your brain processing the sound. | 0:37:19 | 0:37:22 | |
So your visual area's active, and so are your sound areas. | 0:37:22 | 0:37:25 | |
In fact, you've got a set of neurons which combine that experience of sight and sound. | 0:37:25 | 0:37:30 | |
This representation of sight and sound is usually quite reliable, | 0:37:30 | 0:37:33 | |
because sights usually go with sounds, but sometimes | 0:37:33 | 0:37:36 | |
it can lead you to some false and surprising conclusions. | 0:37:36 | 0:37:40 | |
BELCHING SOUNDS | 0:37:42 | 0:37:45 | |
Let's try that one more time. | 0:37:45 | 0:37:48 | |
BELCHING SOUNDS | 0:37:48 | 0:37:50 | |
So, what you're doing there is you think that the skull is burping, | 0:37:50 | 0:37:54 | |
but of course he isn't really, what's happening | 0:37:54 | 0:37:57 | |
is you're seeing the skull move and you're hearing the sound | 0:37:57 | 0:38:01 | |
and your brain's readily putting those things together. | 0:38:01 | 0:38:04 | |
This is called the ventriloquist effect. | 0:38:04 | 0:38:06 | |
And so, when people see ventriloquists they think they're throwing their voice, | 0:38:06 | 0:38:10 | |
but they're not really throwing their voice, | 0:38:10 | 0:38:13 | |
they're minimising the movement of their own mouths, | 0:38:13 | 0:38:16 | |
making a sound, and exaggerating the mouth of the puppet. | 0:38:16 | 0:38:19 | |
I can do that for a little bit, let's see if I can try | 0:38:19 | 0:38:22 | |
and convince you this skull is talking, | 0:38:22 | 0:38:24 | |
So if I go, she sells seashells on the seashore. | 0:38:24 | 0:38:29 | |
OK. | 0:38:29 | 0:38:30 | |
Not only does a ventriloquist shape where you think a sound's coming from, | 0:38:30 | 0:38:35 | |
because sights and sounds usually come from the same place, | 0:38:35 | 0:38:38 | |
the ventriloquist effect can also influence what you're hearing. | 0:38:38 | 0:38:42 | |
So, in this next example, I want you to watch very carefully | 0:38:42 | 0:38:45 | |
this little bit of video and see if you can hear what I'm saying. | 0:38:45 | 0:38:49 | |
REPEATS EITHER "BA-BA! OR "DA-DA" | 0:38:51 | 0:38:55 | |
What did you hear? | 0:38:55 | 0:38:57 | |
AUDIENCE GIVES A MIXED RESPONSE | 0:38:57 | 0:39:00 | |
Who heard "da-da", put your hand up? | 0:39:00 | 0:39:03 | |
OK, everybody sitting in the middle. Let's try it again. | 0:39:03 | 0:39:06 | |
REPEATS EITHER 'BA-BA' OR 'DA-DA' | 0:39:06 | 0:39:10 | |
What do you hear? "Da-da?" | 0:39:10 | 0:39:12 | |
Middle section only, what did you hear? | 0:39:12 | 0:39:14 | |
"Da?" "Ba?" | 0:39:14 | 0:39:16 | |
MIXED RESPONSE | 0:39:16 | 0:39:18 | |
All right, let's make this easier. | 0:39:18 | 0:39:20 | |
I want you to listen again, but close your eyes, OK? | 0:39:20 | 0:39:24 | |
REPEATS EITHER "BA-BA" OR "DA-DA" | 0:39:26 | 0:39:30 | |
What did you hear this time? | 0:39:30 | 0:39:32 | |
AUDIENCE: "Ba". | 0:39:32 | 0:39:33 | |
Definitely it was "Ba". | 0:39:33 | 0:39:34 | |
If you heard "da" you were being fooled by an illusion called the McGurk effect, | 0:39:34 | 0:39:39 | |
because I'm not actually mouthing "ba-ba" or "da-da", | 0:39:39 | 0:39:42 | |
what I'm mouthing is "ga-ga". | 0:39:42 | 0:39:45 | |
So the brain gets the signal of "ga", and it's hearing "ba", | 0:39:45 | 0:39:48 | |
but these are patterns it's never encountered before, | 0:39:48 | 0:39:51 | |
and it comes up with a solution which is "da". | 0:39:51 | 0:39:54 | |
So your brain's always trying to interpret experiences | 0:39:54 | 0:39:58 | |
to come up with the best solution. | 0:39:58 | 0:40:00 | |
Now, this way when you're watching people speak, | 0:40:00 | 0:40:03 | |
you watch their mouths moving and the shape of their mouths | 0:40:03 | 0:40:06 | |
can influence what you think you're hearing. | 0:40:06 | 0:40:08 | |
Here's a very simple party trick - | 0:40:08 | 0:40:10 | |
I want you to turn to the person next to you | 0:40:10 | 0:40:13 | |
and mouth the words "elephant juice". Don't say it, just mouth it. | 0:40:13 | 0:40:17 | |
Turn to the person next to you. | 0:40:17 | 0:40:19 | |
What does it sound like? What do you think the person might be saying? | 0:40:23 | 0:40:27 | |
Why are you laughing? | 0:40:27 | 0:40:30 | |
OK, OK. | 0:40:30 | 0:40:32 | |
Does it look like they could be saying "I love you"? | 0:40:32 | 0:40:35 | |
Do I hear "I love you"? | 0:40:35 | 0:40:37 | |
I love you all, wouldn't the world be a greater place | 0:40:37 | 0:40:40 | |
if everyone said "elephant juice" a little more often to each other? | 0:40:40 | 0:40:45 | |
OK, so your brain is not just forming representations | 0:40:45 | 0:40:50 | |
of the outside world, it's also storing these representations of your own bodies, | 0:40:50 | 0:40:55 | |
and so for this next demonstration I'm going to require someone | 0:40:55 | 0:40:59 | |
who doesn't mind losing their hand. | 0:40:59 | 0:41:01 | |
Lady on the end here, why don't you come down? | 0:41:02 | 0:41:06 | |
APPLAUSE | 0:41:06 | 0:41:10 | |
It's all right, just there. What's your name, first of all? | 0:41:10 | 0:41:14 | |
-Josie. -Josie, so you're quite prepared to lose your hand | 0:41:14 | 0:41:18 | |
for medical science, is that correct? You don't mind losing a hand? | 0:41:18 | 0:41:22 | |
Don't worry, I'm not going to remove your hand, | 0:41:22 | 0:41:24 | |
I'm going to create the illusion that you're losing your hand. | 0:41:24 | 0:41:28 | |
So, for this I need you to put on this very strange jacket. | 0:41:28 | 0:41:31 | |
It's actually got three arms. | 0:41:31 | 0:41:33 | |
OK, so put your arm through that one, then through the other one. | 0:41:33 | 0:41:37 | |
That's the regular part of the jacket. | 0:41:37 | 0:41:39 | |
Is that going to be a bit small for you? Perfect. | 0:41:39 | 0:41:42 | |
-Now, we're going to torture you. OK, so now, Josie, did you say? -Yes. | 0:41:42 | 0:41:46 | |
OK, Josie, take a seat. I want you to put your other hand | 0:41:46 | 0:41:49 | |
up here, your left hand, both hands are there. | 0:41:49 | 0:41:52 | |
OK, now, that looks a little bit strange, | 0:41:52 | 0:41:55 | |
but I want you just to focus on this, this is a rubber hand. | 0:41:55 | 0:41:59 | |
It's about the same size as Josie's hand, and I want you | 0:41:59 | 0:42:02 | |
not to look at the audience, just concentrate on the hand, OK? | 0:42:02 | 0:42:05 | |
This illusion takes about a minute or two to form. | 0:42:05 | 0:42:09 | |
What should happen is that Josie is looking at this hand of hers, | 0:42:09 | 0:42:13 | |
and it's in the same place her normal hand is. | 0:42:13 | 0:42:16 | |
So, her brain is a little bit confused, because that hand should belong to her. | 0:42:16 | 0:42:22 | |
At the same time, to make the illusion even more strong, | 0:42:22 | 0:42:25 | |
Kate is simultaneously stroking the hands, | 0:42:25 | 0:42:28 | |
so the brain is now receiving all this touch information. | 0:42:28 | 0:42:32 | |
Again, it's combining information, trying to make sense of it. | 0:42:32 | 0:42:36 | |
-How does that feel? -It feels really weird. | 0:42:36 | 0:42:39 | |
-Does it feel very weird? -Yeah. -OK. | 0:42:39 | 0:42:42 | |
So, just keep doing that for a moment. | 0:42:42 | 0:42:44 | |
Now just keep focusing on the hand, OK? | 0:42:49 | 0:42:53 | |
Ready? | 0:42:53 | 0:42:54 | |
Did you get a strange... Did that feel a bit odd? | 0:42:55 | 0:42:58 | |
OK, don't worry, I wasn't going to hurt your hand. | 0:42:58 | 0:43:00 | |
Round of applause. | 0:43:00 | 0:43:02 | |
APPLAUSE | 0:43:02 | 0:43:06 | |
Thank you very much. Well done. | 0:43:10 | 0:43:12 | |
Now, the reason that happened is because the brain wasn't | 0:43:12 | 0:43:15 | |
exactly sure whether it was the rubber hand any more, | 0:43:15 | 0:43:18 | |
and that's why most people you do that experiment with get this surprise. | 0:43:18 | 0:43:22 | |
I can't bring you all down to try the rubber hand illusion, | 0:43:22 | 0:43:26 | |
but I can show you a similar experience, | 0:43:26 | 0:43:28 | |
so I'll need another volunteer, someone from this side. | 0:43:28 | 0:43:31 | |
Young lady in the blue, why don't you come down? | 0:43:31 | 0:43:33 | |
APPLAUSE | 0:43:35 | 0:43:38 | |
-What's your name? -Charlotte. | 0:43:38 | 0:43:40 | |
OK, Charlotte, here's a very simple way to induce the rubber hand illusion. | 0:43:40 | 0:43:44 | |
I'm just going to turn you this way for a bit. | 0:43:44 | 0:43:46 | |
There you go, Charlotte. Now put up your right hand. | 0:43:46 | 0:43:49 | |
OK. | 0:43:49 | 0:43:51 | |
Now, with your other hand just grip like this. | 0:43:51 | 0:43:55 | |
Now, looking at your index finger, just move your fingers up and down whilst you're doing it. | 0:43:55 | 0:44:00 | |
-Does that feel a little strange? You can all try this. -Yes. | 0:44:00 | 0:44:03 | |
Just turn to the person next to you. | 0:44:03 | 0:44:06 | |
With your thumb and forefinger see if you can do this. | 0:44:06 | 0:44:10 | |
It's strange, isn't it? It is very, very weird. | 0:44:12 | 0:44:15 | |
You can try it at home as well, if you like. | 0:44:15 | 0:44:18 | |
All right, guys, let's settle down. | 0:44:24 | 0:44:27 | |
Let's give a round of applause to Charlotte. | 0:44:27 | 0:44:30 | |
-APPLAUSE -Thank you, Charlotte. | 0:44:30 | 0:44:34 | |
So, your brain is always trying to make sense of the world. | 0:44:38 | 0:44:41 | |
Sometimes, when it gets strange signals, it comes up with strange experiences and illusions. | 0:44:41 | 0:44:46 | |
We see things all the time. It might be faces in a cloud or animals in ink stains. | 0:44:46 | 0:44:53 | |
Just simple coffee beans. | 0:44:53 | 0:44:55 | |
If I scatter them onto here, you can see all sorts of patterns in that. | 0:44:55 | 0:45:01 | |
Can anyone see a pattern forming there at all? | 0:45:01 | 0:45:05 | |
Shout if you see anything. | 0:45:05 | 0:45:07 | |
There's a mouse? | 0:45:07 | 0:45:09 | |
SHOUTING FROM AUDIENCE | 0:45:09 | 0:45:12 | |
What else? | 0:45:12 | 0:45:13 | |
Oh... | 0:45:15 | 0:45:16 | |
AUDIENCE SHOUTS | 0:45:16 | 0:45:19 | |
OK. | 0:45:19 | 0:45:20 | |
So, you're all seeing lots of patterns. That's very good. | 0:45:22 | 0:45:27 | |
OK. Clearly you're all seeing lots of things. That's very reassuring. | 0:45:27 | 0:45:31 | |
Your brain always tries to impose structure and order. | 0:45:31 | 0:45:34 | |
This is most obvious with certain types of illusions | 0:45:34 | 0:45:38 | |
where you have patterns which can be seen in more than one way. | 0:45:38 | 0:45:42 | |
Probably one of the most famous examples is called The Necker Cube. | 0:45:42 | 0:45:46 | |
Here is a Necker Cube. | 0:45:46 | 0:45:48 | |
It is an outline of a cube. If you look at it long enough, you think it's pointing in one direction | 0:45:48 | 0:45:53 | |
but then, if you stare at it long enough, your brain switches | 0:45:53 | 0:45:57 | |
and it appears to be in the opposite direction. | 0:45:57 | 0:46:01 | |
Is anyone having that experience? Hands up. | 0:46:01 | 0:46:03 | |
That's great. | 0:46:03 | 0:46:05 | |
We can make it stronger if we put a bit of movement into it. | 0:46:05 | 0:46:07 | |
So just watch as it turns. | 0:46:07 | 0:46:11 | |
It seems to be going in one direction. Then, is anyone getting it turning in the other direction? | 0:46:11 | 0:46:18 | |
Yeah? Just watch. You know what makes it really good? | 0:46:18 | 0:46:23 | |
If you blink, while you're watching, you'll see it switch. | 0:46:23 | 0:46:26 | |
We're not using any computer trickery here. | 0:46:26 | 0:46:30 | |
It's simply your brain switching from one version versus the other. | 0:46:30 | 0:46:34 | |
Isn't that remarkable? | 0:46:36 | 0:46:38 | |
AUDIENCE MURMURS | 0:46:38 | 0:46:40 | |
Here is another interesting point. | 0:46:40 | 0:46:42 | |
Your brain doesn't allow you to see all the patterns at once. | 0:46:42 | 0:46:47 | |
It forces you into one perception versus the other. | 0:46:47 | 0:46:50 | |
This might explain why some of you sometimes see things like ghosts, for example. | 0:46:50 | 0:46:56 | |
I am going to conjure up a ghost in front of your very eyes, OK? | 0:46:56 | 0:47:00 | |
Don't worry, it won't be a headless horseman. It'll be more simple and friendly than that. | 0:47:00 | 0:47:06 | |
All you need for this, | 0:47:06 | 0:47:07 | |
and you can try this at home, are just four circles of paper. | 0:47:07 | 0:47:11 | |
It's such a simple illusion but it's very compelling. | 0:47:11 | 0:47:14 | |
All I have to do his cut a quarter of the circle. | 0:47:18 | 0:47:22 | |
If you then align up the circles... | 0:47:29 | 0:47:32 | |
..you will see something that isn't really there. | 0:47:34 | 0:47:39 | |
What does anyone see? Hands up. Shout out. | 0:47:40 | 0:47:43 | |
-AUDIENCE SHOUTS -That's right. A square. | 0:47:43 | 0:47:46 | |
But, of course, there isn't a square there, is there? | 0:47:46 | 0:47:49 | |
When I take this away it disappears and back it comes again. | 0:47:49 | 0:47:53 | |
This is a very simple illusion, but it's also a very powerful one | 0:47:53 | 0:47:57 | |
because I think it explains one of the most important points about the brain. | 0:47:57 | 0:48:02 | |
If I went into the back of your brain with a wire, I could measure activity | 0:48:02 | 0:48:08 | |
of neurons which are firing as if they're really was a square there. | 0:48:08 | 0:48:12 | |
So this is remarkable - the brain is creating its own experience, isn't it? | 0:48:12 | 0:48:18 | |
In fact, we can even show that you think this is a solid object. | 0:48:18 | 0:48:23 | |
They've done this recently in an experiment | 0:48:23 | 0:48:25 | |
where they've put people in a brain scanner and they've showed them this square. | 0:48:25 | 0:48:30 | |
It's called the Kanizsa Illusion. | 0:48:30 | 0:48:32 | |
Here we have the square. Then they made the square move. | 0:48:33 | 0:48:37 | |
You see, it is travelling across. | 0:48:39 | 0:48:43 | |
Watch as it moves across the screen. | 0:48:43 | 0:48:47 | |
There it goes again. Undulating like a real object. | 0:48:50 | 0:48:53 | |
Isn't that very bizarre? | 0:48:55 | 0:48:57 | |
AUDIENCE MURMURS | 0:48:59 | 0:49:03 | |
It's moving across the screen. See if we can move it a bit faster. | 0:49:03 | 0:49:08 | |
There it goes, moving across the screen. | 0:49:08 | 0:49:10 | |
What's remarkable is that the movement areas of the brain are being activated | 0:49:15 | 0:49:19 | |
which are going in the same direction as the illusory ghostly square. | 0:49:19 | 0:49:24 | |
So, your brain doesn't allow you to have contact with reality. | 0:49:24 | 0:49:28 | |
It is generating reality the whole time. | 0:49:28 | 0:49:31 | |
It is quite remarkable. | 0:49:31 | 0:49:33 | |
Let us come back to Charlie and Iona, at the beginning. | 0:49:33 | 0:49:37 | |
Let's get them back in for the rest of the show. | 0:49:37 | 0:49:40 | |
Where are you? Come one down. | 0:49:40 | 0:49:42 | |
A big round of applause, please. | 0:49:42 | 0:49:44 | |
APPLAUSE | 0:49:44 | 0:49:47 | |
-So, guys, how are you enjoying the show so far? -It is great. | 0:49:50 | 0:49:53 | |
Reality hasn't changed for you. You're still very tall, Charlie, | 0:49:53 | 0:49:55 | |
-and you're still A bit shorter, aren't you? -Yes. -Would you like to be taller than Charlie? -Yes. | 0:49:55 | 0:50:01 | |
Well, with the RI Christmas show we can actually make that happen | 0:50:01 | 0:50:05 | |
so please follow Kate out of the room for a moment. | 0:50:05 | 0:50:08 | |
We will be seeing them very shortly. | 0:50:08 | 0:50:11 | |
Throughout the lecture tonight, we've been watching how reality is created by the brain. | 0:50:11 | 0:50:17 | |
And it uses past experiences to make sense of the world. | 0:50:17 | 0:50:21 | |
But things are not always as they seem. | 0:50:21 | 0:50:25 | |
Sometimes we can fool the... | 0:50:25 | 0:50:28 | |
Oh! Hello, guys. | 0:50:28 | 0:50:30 | |
There we go! Can you give a wave, Charlie. | 0:50:30 | 0:50:32 | |
-Charlie, that room seems a bit small, doesn't it? -Yeah. | 0:50:32 | 0:50:36 | |
Maybe you should try going to the opposite corner. | 0:50:36 | 0:50:40 | |
-Iona, why don't you switch places? -OK. -OK. | 0:50:40 | 0:50:42 | |
Oh, my gosh! How did that happen? Switch places again. | 0:50:44 | 0:50:49 | |
Can you hold hands? Can you reach each other? | 0:50:54 | 0:50:57 | |
There we go. | 0:50:57 | 0:50:59 | |
Look, it's a giant and a smaller person. | 0:50:59 | 0:51:02 | |
OK. You can have the bit of fun in there because I'll explain what's going on. | 0:51:03 | 0:51:07 | |
To do that, I need a model. | 0:51:07 | 0:51:10 | |
What you can't see is that's obviously not a normal room. | 0:51:10 | 0:51:13 | |
In fact, the room has this sort of shape. | 0:51:13 | 0:51:17 | |
It is just the way we have set the camera angle. | 0:51:17 | 0:51:20 | |
What week doing is fooling and tricking your brain into thinking that is, in fact, a square room. | 0:51:20 | 0:51:27 | |
I can illustrate this with the next example over here. | 0:51:27 | 0:51:30 | |
Do these lines look equally long to you? | 0:51:33 | 0:51:36 | |
AUDIENCE: Yes. | 0:51:36 | 0:51:38 | |
The green lines? Who says they look the same? | 0:51:38 | 0:51:41 | |
That is a very strange brain you have. The rest of you, I hope... | 0:51:41 | 0:51:45 | |
Who things they look longer? | 0:51:45 | 0:51:47 | |
That's great! Because, of course, it's an illusion. | 0:51:48 | 0:51:53 | |
This is the Ponzo Illusion. | 0:51:53 | 0:51:55 | |
In fact, the lines are exactly the same length. | 0:51:55 | 0:51:58 | |
I'm going to make that big again. | 0:52:00 | 0:52:02 | |
What is going on here is your brain has been fooled by what are called perspective cues. | 0:52:02 | 0:52:08 | |
It's almost like it's on a railway track | 0:52:08 | 0:52:10 | |
and because railway tracks recede off into the distance, they converge. | 0:52:10 | 0:52:15 | |
Because this seems to be further away | 0:52:15 | 0:52:18 | |
and it is stretching over the edge, we assume it must be much larger | 0:52:18 | 0:52:22 | |
than this block which is sitting inside the tracks. | 0:52:22 | 0:52:25 | |
Once again, even though your brain tells you that they look different | 0:52:25 | 0:52:28 | |
in fact they are exactly the same length. | 0:52:28 | 0:52:32 | |
So, at this is what is going on in the Ames Room. | 0:52:34 | 0:52:37 | |
It uses these perspective cues of slanted lines to fool your brain | 0:52:37 | 0:52:41 | |
into thinking that the room is actually the same distance. | 0:52:41 | 0:52:45 | |
In fact, it is actually longer. | 0:52:45 | 0:52:47 | |
I suppose the best way to show you how it will work is if I go out there | 0:52:47 | 0:52:50 | |
and you can see what I am like and what the room is really like. OK? | 0:52:50 | 0:52:55 | |
-Here we are at the Ames Room. How are you doing? -Fine. | 0:53:00 | 0:53:03 | |
If you have a look a round, | 0:53:03 | 0:53:04 | |
you can see that the room the room isn't straight or normal. | 0:53:04 | 0:53:07 | |
It has slanting lines and the way the team have built it... | 0:53:07 | 0:53:11 | |
when you shoot it from one angle it looks as if the perspective is correct, | 0:53:11 | 0:53:15 | |
but in fact it is entirely wrong. Why don't you swap over again? | 0:53:15 | 0:53:18 | |
In fact, I think I'll join you. | 0:53:18 | 0:53:21 | |
So you can watch me going into the room | 0:53:21 | 0:53:23 | |
and look how I transform in size. Here I come! | 0:53:23 | 0:53:25 | |
So, I'm big. | 0:53:25 | 0:53:27 | |
And now, Iona, you're bigger than both of us. | 0:53:30 | 0:53:34 | |
So, that's part of the magic of the Royal Institution. | 0:53:34 | 0:53:37 | |
Why don't you come back in and give a big round of applause for everyone? | 0:53:37 | 0:53:42 | |
APPLAUSE | 0:53:42 | 0:53:44 | |
So, all these illusions demonstrate | 0:53:53 | 0:53:55 | |
our brains constantly try to make sense of the world | 0:53:55 | 0:53:58 | |
and understand based on these stored representations. | 0:53:58 | 0:54:01 | |
The remarkable thing about illusions is, even when you know how they work, | 0:54:01 | 0:54:04 | |
and I've just demonstrated with the models and shown | 0:54:04 | 0:54:07 | |
that these are illusions, you can't help but see them one way or the other. | 0:54:07 | 0:54:11 | |
It's because your brain is creating your mind's experience. | 0:54:11 | 0:54:14 | |
You can't avoid that. | 0:54:14 | 0:54:15 | |
So, you remember I promised you we were going to look at Thalia's brain | 0:54:15 | 0:54:19 | |
and read her mind? Let's go back to Cheltenham and see if we've made that link. | 0:54:19 | 0:54:24 | |
Hello, Cheltenham, can you hear me at all? | 0:54:24 | 0:54:27 | |
-It's Cheltenham here. Hi, London. -Is that Iain, is it? | 0:54:27 | 0:54:30 | |
Yes, hi, Bruce, hi! | 0:54:30 | 0:54:32 | |
Hi, hi! How's it been going? Have you managed to scan Thalia's brain? | 0:54:32 | 0:54:36 | |
Yeah, we've got some great pictures. It looks good. | 0:54:36 | 0:54:38 | |
Good. Can you send through the first image so we can get an idea of what you've got. | 0:54:38 | 0:54:42 | |
-That's structural image, is that correct? -Yeah. | 0:54:42 | 0:54:45 | |
So, I'm going to tell the audience, to give them an idea what they're looking at. | 0:54:45 | 0:54:51 | |
Imagine I'm Thalia and I'm lying inside the scanner. Here I am. | 0:54:51 | 0:54:55 | |
And so the scan is going from the bottom of my brain up to the top of my head. | 0:54:55 | 0:55:00 | |
So this side of the screen is the right side of my brain, OK? | 0:55:00 | 0:55:05 | |
This side of the image on this side of the screen is the left side of my brain. | 0:55:05 | 0:55:10 | |
So, Iain, am I correct? Did you try showing Thalia a visual image earlier, is that right? | 0:55:10 | 0:55:16 | |
Yes, we did. We showed her a visual object, yeah. | 0:55:16 | 0:55:19 | |
Can you show us what the brain activation was like | 0:55:19 | 0:55:23 | |
when she was looking at a visual object? OK. | 0:55:23 | 0:55:26 | |
So, tell us, what part of the brain is that that's being activated? | 0:55:26 | 0:55:30 | |
-The back. -So, if it's the back part of the brain, what's going on? | 0:55:30 | 0:55:35 | |
-Which area's that? -Vision. -That's right. We showed Thalia a picture. | 0:55:35 | 0:55:39 | |
When she looked at the picture, the back of her brain was more active. | 0:55:39 | 0:55:43 | |
This was showing the functions of her brain working. | 0:55:43 | 0:55:45 | |
Now, Thalia, we asked her to... | 0:55:45 | 0:55:49 | |
we had a walnut and we asked her to put it in one of her hands. | 0:55:49 | 0:55:52 | |
Have you been processing that image, Iain? | 0:55:52 | 0:55:54 | |
Yes, we have. We've been processing the image. | 0:55:54 | 0:55:57 | |
You say she had a walnut in one hand. We took some pictures while she was squeezing the walnut with her hand. | 0:55:57 | 0:56:02 | |
Great. Have you got those images ready for us? OK. | 0:56:02 | 0:56:05 | |
So, if that's the image, which side of the brain is more active? Which side of the image is it? | 0:56:05 | 0:56:10 | |
-Right. -So, it's on the right side. | 0:56:10 | 0:56:13 | |
This is the right side of my brain. What you've learned tonight | 0:56:13 | 0:56:16 | |
about how things cross over, which hand is Thalia holding the walnut in? | 0:56:16 | 0:56:20 | |
-Left! -Thalia, could you confirm to me which hand you were squeezing the walnut with? | 0:56:20 | 0:56:26 | |
My left hand. | 0:56:26 | 0:56:29 | |
Thank you. | 0:56:29 | 0:56:32 | |
You have just mind read Thalia because you predicted which hand | 0:56:33 | 0:56:36 | |
she was holding it in. Do you realise that's over 100 miles away? | 0:56:36 | 0:56:41 | |
A big round of applause, everyone. | 0:56:41 | 0:56:43 | |
APPLAUSE | 0:56:43 | 0:56:45 | |
Before we go, can we say thank you and good night to Thalia and Iain? Good night, Cheltenham. | 0:56:53 | 0:56:57 | |
Good night. | 0:56:57 | 0:56:59 | |
So, that's what's inside your head. | 0:56:59 | 0:57:01 | |
Your brain is interpreting the world around you into meaningful patterns | 0:57:01 | 0:57:06 | |
and storing those patterns of representations. With these technologies | 0:57:06 | 0:57:10 | |
we can read the activity of the brain. | 0:57:10 | 0:57:12 | |
Does that mean, to know what's on someone's mind, we have to look at brain activity? | 0:57:12 | 0:57:16 | |
The technologies are useful if you know what you're looking for | 0:57:16 | 0:57:19 | |
and the tasks are very simple, like squeezing a walnut in one hand. | 0:57:19 | 0:57:24 | |
But, the thing about humans is, we're very complicated. | 0:57:24 | 0:57:27 | |
The tasks we can do are very difficult. | 0:57:27 | 0:57:29 | |
That's what makes us human in many ways. | 0:57:29 | 0:57:31 | |
So, that raises the question, | 0:57:31 | 0:57:34 | |
who was coordinating all these difficult tasks and activities? | 0:57:34 | 0:57:38 | |
Who is in charge anyway? We'll be addressing that in the next lecture. | 0:57:38 | 0:57:43 | |
Good night and look after your brains. Good night. | 0:57:43 | 0:57:46 | |
CHEERING AND APPLAUSE | 0:57:46 | 0:57:50 |