0:00:02 > 0:00:03Meet Charlie and Iona.
0:00:03 > 0:00:06As you can plainly see, Charlie is much taller than Iona.
0:00:06 > 0:00:10But sometimes reality is not what it seems.
0:00:55 > 0:00:59Welcome to the 2011 Royal Institution Christmas Lectures,
0:00:59 > 0:01:01Meet Your Brain.
0:01:01 > 0:01:02Let me introduce myself.
0:01:02 > 0:01:06I'm Bruce Hood, and I am a scientist interested in the human brain,
0:01:06 > 0:01:10what it is and how it changes as we grow older.
0:01:10 > 0:01:15Actually, when I said "I am Bruce Hood" what I really should have said is, "This is Bruce Hood".
0:01:15 > 0:01:19Because everything I am is really a product of my brain.
0:01:19 > 0:01:21It's not my heart, it's not my kidneys -
0:01:21 > 0:01:24these are important organs, but I could have them transplanted
0:01:24 > 0:01:26and I'd still be the same person.
0:01:26 > 0:01:30That's because it's our brain that makes us who we are.
0:01:30 > 0:01:33In this series of lectures, we're going to be looking at the human brain,
0:01:33 > 0:01:38what it is, how it works and most importantly, how it interacts with other brains.
0:01:38 > 0:01:42But before I do so, I'd like to introduce you to someone else here.
0:01:42 > 0:01:47Or rather, someone who is here no longer.
0:01:48 > 0:01:52This is a real human brain, from a person.
0:01:54 > 0:01:58Before they died, they made the decision to donate their brain to science,
0:01:58 > 0:02:00so that we could discover
0:02:00 > 0:02:05the workings of this most astonishing, amazing organ.
0:02:08 > 0:02:10It is so mysterious and complicated,
0:02:10 > 0:02:13we can't even begin to really know how it works!
0:02:15 > 0:02:18I brought this brain along tonight to remind you
0:02:18 > 0:02:22exactly who we are, and what we are trying to understand.
0:02:23 > 0:02:26It is truly awe-inspiring.
0:02:29 > 0:02:32Every one of you here tonight, and watching at home,
0:02:32 > 0:02:34has a brain inside your head.
0:02:34 > 0:02:38Every brain is important. Every brain is unique.
0:02:38 > 0:02:41But all brains have the same basic machinery -
0:02:41 > 0:02:44so how does a brain work?
0:02:44 > 0:02:47To help me answer these questions,
0:02:47 > 0:02:51I've invited along another brain scientist, Professor Vince Walsh from UCL.
0:02:51 > 0:02:53Give a big round of applause to Vince!
0:02:53 > 0:02:55APPLAUSE AND CHEERING
0:02:59 > 0:03:02So Vince, you've brought along this special machine
0:03:02 > 0:03:05that influences the brain.
0:03:05 > 0:03:06We're going to see it in action.
0:03:06 > 0:03:09But before we do, let's start with a simple demonstration.
0:03:09 > 0:03:13Do you know the Nursery Rhyme "Baa Baa Black Sheep"?
0:03:13 > 0:03:15- I think so.- Could you give us the first line?
0:03:15 > 0:03:18Baa baa black sheep, have you any wool?
0:03:18 > 0:03:19That's good.
0:03:19 > 0:03:23Reassuring to know that professors still know their nursery rhymes.
0:03:23 > 0:03:26OK. I'm going to get you to repeat that,
0:03:26 > 0:03:30but this time, I'm going to stimulate this part of your brain
0:03:30 > 0:03:31with your machine.
0:03:31 > 0:03:33Start, please.
0:03:33 > 0:03:34Baa baa black...
0:03:34 > 0:03:36VOICE BECOMES DISTORTED
0:03:36 > 0:03:39LAUGHTER
0:03:40 > 0:03:41Don't be alarmed.
0:03:42 > 0:03:46- You're perfectly OK, Vince, aren't you?- I'm fine, yes. - That's very good.
0:03:46 > 0:03:49Somehow this machine has disrupted Vince's brain.
0:03:49 > 0:03:52This is a trans-magnetic stimulator.
0:03:52 > 0:03:54It's delivering a very powerful magnetic pulse
0:03:54 > 0:03:56for a brief fraction of a second
0:03:56 > 0:04:00but why is it disrupting Vince's ability to speak?
0:04:00 > 0:04:02I'm going to give you a clue with the next demonstration.
0:04:02 > 0:04:05Have a look at this old television over here.
0:04:05 > 0:04:07I'm going to need a magnet.
0:04:08 > 0:04:11You can see the image on the television is perfectly normal
0:04:11 > 0:04:14but look what happens when I bring a magnet close to it.
0:04:18 > 0:04:22You can see the image is being distorted by the magnet.
0:04:22 > 0:04:24Now, why is this?
0:04:24 > 0:04:27Well, remarkably, the answer comes from none other
0:04:27 > 0:04:30than the founder of the Royal Institution Christmas Lectures,
0:04:30 > 0:04:33Michael Faraday, because Faraday discovered over 150 years ago
0:04:33 > 0:04:36and often demonstrated in this very theatre
0:04:36 > 0:04:41that there's a relationship between magnets and electrical fields.
0:04:41 > 0:04:45The image on the television is produced by an electrified beam
0:04:45 > 0:04:47so that when I bring a magnet close to it,
0:04:47 > 0:04:49it's distorting the path of that beam
0:04:49 > 0:04:52and that's why the image is being distorted.
0:04:52 > 0:04:55So let's put these pieces of information together.
0:04:55 > 0:04:57A magnet can disrupt an electrical field.
0:04:57 > 0:05:00We know the magnet is disrupting Vince's ability to speak
0:05:00 > 0:05:05which is a product of his brain so we can conclude that the brain
0:05:05 > 0:05:09must be using some form of electrical communication to make you speak.
0:05:09 > 0:05:12- Is that roughly correct, Vince? - True, yeah.- OK, Vince.
0:05:12 > 0:05:14If I put a magnet next to my head,
0:05:14 > 0:05:19it doesn't seem to disrupt any of my ability to speak, so why is that?
0:05:19 > 0:05:23That's because the field you've got next to your head is static.
0:05:23 > 0:05:26Even though you're moving at about, it's moving very slowly.
0:05:26 > 0:05:31To create an electric field that disturbs brain cells, it's got to move very, very rapidly.
0:05:31 > 0:05:35Every one of those clicks you hear is 1/10000 of a millisecond
0:05:35 > 0:05:38so the field has to change very, very quickly
0:05:38 > 0:05:41to create any electricity in the brain.
0:05:41 > 0:05:44Would you like me to do some more disruption of Vince's brain?
0:05:44 > 0:05:46- AUDIENCE:- Yes. - Vince, I'm sorry,
0:05:46 > 0:05:51but we're going to put you through some more. OK, so, what else shall we try?
0:05:51 > 0:05:53How about some motor control?
0:05:53 > 0:05:56We could do that. We could try left and right-handed.
0:05:56 > 0:06:00Can we try just affecting your right hand, would that be OK?
0:06:00 > 0:06:03Right, so I'm going to take my magnet. Is it fully charged up again?
0:06:03 > 0:06:07- It is.- I'll touch my nose a few times.
0:06:07 > 0:06:10Let's see how accurate it you are when I place it up here.
0:06:10 > 0:06:12- Is that the correct area?- Mhm.
0:06:12 > 0:06:15ELECTRICAL CLICKING
0:06:15 > 0:06:16AUDIENCE LAUGHS
0:06:16 > 0:06:20Vince, tell the audience what that feels like?
0:06:20 > 0:06:24It's actually quite painless but I've lost control of my muscles.
0:06:24 > 0:06:30I've lost control of my ability to locate my hand in space.
0:06:30 > 0:06:33- It's a very, very weird sensation. - Can we do one last example?
0:06:33 > 0:06:35Can you, um...can you clap for us?
0:06:35 > 0:06:39I'm just going to stick the magnet here, here we go.
0:06:39 > 0:06:41You ready? Start clapping, please.
0:06:42 > 0:06:43ELECTRICAL CLICKING
0:06:43 > 0:06:44AUDIENCE LAUGHS
0:06:44 > 0:06:47OK, I think we've put you through enough, Vince.
0:06:47 > 0:06:50Before you go, tell us, please.
0:06:50 > 0:06:53We've seen how a magnet can disrupt normal function,
0:06:53 > 0:06:54but does it have any application?
0:06:54 > 0:06:57It does. What we've done has been very dramatic.
0:06:57 > 0:07:00We've been using very high magnetic fields to influence the brain
0:07:00 > 0:07:03so we can see that it does affect the brain but if we use lower fields
0:07:03 > 0:07:07and stimulate specific areas of the brain, we can work on treating
0:07:07 > 0:07:11things like depression, or modelling brain disorders
0:07:11 > 0:07:13or modelling stroke in real research,
0:07:13 > 0:07:15so it's got lots and lots of applications.
0:07:15 > 0:07:17Vince, that's been absolutely fascinating.
0:07:17 > 0:07:20Would everyone give Vince a round of applause.
0:07:20 > 0:07:22APPLAUSE
0:07:32 > 0:07:35Do you realise we've just proved that the brain
0:07:35 > 0:07:38is an electrical system, and I think that's pretty cool.
0:07:38 > 0:07:41Not only do magnets disrupt brain function
0:07:41 > 0:07:44but we can use magnets to look at the workings of the brain.
0:07:44 > 0:07:47But to do so you have to have a very powerful magnet.
0:07:47 > 0:07:50And we happen to have access to one not here in London
0:07:50 > 0:07:54but up in Cheltenham where we've set up a live link.
0:07:54 > 0:07:56We recorded this earlier.
0:07:56 > 0:07:57Hello, I'm Dr Thalia Gjersoe
0:07:57 > 0:08:01and I'm here at the MRI scanner so you can read my mind.
0:08:01 > 0:08:06I'm here with Iain Lyburn who's going to take us through it.
0:08:06 > 0:08:08Welcome to the Cheltenham Imaging Centre.
0:08:08 > 0:08:11It's run by the Cobalt Appeal Fund
0:08:11 > 0:08:14and houses imaging for PET and MRI
0:08:14 > 0:08:18and today we're going to have an MRI scan looking at your brain, seeing how it works.
0:08:18 > 0:08:21What I'd like to do is show you the scanner first of all.
0:08:21 > 0:08:25- Have you seen it before? - No, I haven't. - Shall we've a look inside?- OK.
0:08:28 > 0:08:32It's got a big metal door because it's housed in a big metal cage.
0:08:32 > 0:08:33This is the scanner.
0:08:33 > 0:08:36You'll be going in with your head in the scanner
0:08:36 > 0:08:40and it's got a very strong magnetic field which is part of the way it works.
0:08:40 > 0:08:43Karen's going to show us how strong the magnet is.
0:08:43 > 0:08:47- She's actually got...- I've got a spanner on the end of a bit of rope.
0:08:55 > 0:08:59You can see how powerful it is. So that's how strong it is.
0:09:00 > 0:09:02Quite impressive that, actually, isn't it?
0:09:02 > 0:09:06- Wow. Iain, can you hear me? - Yes, hi, good evening.
0:09:06 > 0:09:09We've just seen this magnet of yours.
0:09:09 > 0:09:12It's extraordinarily powerful. How powerful is it?
0:09:12 > 0:09:1530,000 times as strong as the magnetic field of the Earth.
0:09:15 > 0:09:19That sounds dangerous to me. Why doesn't it affect the human brain
0:09:19 > 0:09:21when you put someone in a scanner?
0:09:21 > 0:09:23Well, the magnet's actually fixed.
0:09:23 > 0:09:25It doesn't move, there's no movement,
0:09:25 > 0:09:28so it's safe to go in and use for imaging.
0:09:29 > 0:09:33So it's not like the TMS. It's a static magnetic field.
0:09:33 > 0:09:37- Is that correct?- It's a static magnetic field, so it's safe.- OK.
0:09:37 > 0:09:40- Thalia, can you hear me? - Yes, I can, Bruce. Hello.
0:09:40 > 0:09:43I wouldn't go into that machine with anything magnetic.
0:09:43 > 0:09:46Have you got something small that you can put in your hand?
0:09:46 > 0:09:50- I do. I've got a walnut. - You've got a walnut? All right.
0:09:50 > 0:09:54Well, I want you to take the walnut into the scanner, OK,
0:09:54 > 0:09:56and don't tell us which hand you're going to put it in
0:09:56 > 0:10:00because were we're going to do a bit of mind reading, I think.
0:10:00 > 0:10:04We'll be seeing a bit more of you later on. Or, should I say, we'll be seeing more of your brain.
0:10:04 > 0:10:06For the moment, though,
0:10:06 > 0:10:10can we give a warm round of applause to Thalia and Professor Iain Lyburn.
0:10:10 > 0:10:14APPLAUSE
0:10:16 > 0:10:19So all brains work by electrical signalling
0:10:19 > 0:10:23and all brains are very similar but they can also be quite different, in some ways.
0:10:23 > 0:10:26Take a look at all of these animal brains.
0:10:26 > 0:10:29Take a guess at which brain you think this animal belongs to.
0:10:29 > 0:10:32I'm going to give you a pound coin so you can estimate the size.
0:10:32 > 0:10:36- Now, what animal do you think that might be? Shout it out.- Spider!
0:10:36 > 0:10:37A spider?
0:10:37 > 0:10:40- No, it's not a spider. Can we have another example?- Mouse!
0:10:40 > 0:10:45Mouse? Who said mouse? Hands up. You're correct. It's a mouse.
0:10:45 > 0:10:46OK, what about this creature here?
0:10:46 > 0:10:47Rat.
0:10:47 > 0:10:49Did someone say rat?
0:10:49 > 0:10:53AUDIENCE CALL OUT
0:10:53 > 0:10:56It's a rat's brain. What about this brain here?
0:10:56 > 0:11:00AUDIENCE CALL OUT
0:11:00 > 0:11:04It's a...it's a chicken. Believe it or not, that's a chicken's brain.
0:11:04 > 0:11:06And what about this one here?
0:11:06 > 0:11:08AUDIENCE CALL OUT
0:11:08 > 0:11:10A tortoise? No. No.
0:11:10 > 0:11:11AUDIENCE CALL OUT
0:11:11 > 0:11:16It's a cat's brain. And here we have... a dog.
0:11:17 > 0:11:20And finally this one. What's this one belong to?
0:11:20 > 0:11:21AUDIENCE CALL OUT
0:11:21 > 0:11:23A horse. Who said a horse?
0:11:23 > 0:11:25Hands up if you said horse.
0:11:25 > 0:11:27Let's consider the horse for a moment.
0:11:27 > 0:11:31It's a very large animal, isn't it? A horse is on average three times bigger than a human
0:11:31 > 0:11:35but look at the horse's brain in comparison to the human brain.
0:11:35 > 0:11:37Let me take it around to show you.
0:11:38 > 0:11:40Even though a horse is much larger than a human,
0:11:40 > 0:11:43the brain is actually smaller
0:11:43 > 0:11:45so this shows you the size of the body size
0:11:45 > 0:11:47doesn't predict the size of the brain.
0:11:47 > 0:11:51In fact, if you think about the size of a human body on average,
0:11:51 > 0:11:55our brain is seven times larger than you would ever imagine.
0:11:55 > 0:11:59So, who would like to hold a human brain?
0:11:59 > 0:12:01That's an awful lot of you.
0:12:01 > 0:12:03Unfortunately, we can't let you hold the human brain
0:12:03 > 0:12:06but I just happen to have one which is just as good,
0:12:06 > 0:12:08made out of synthetic plastic over here.
0:12:12 > 0:12:13It's a very good copy.
0:12:13 > 0:12:18It's the same shape, it's the same size and it's the same weight.
0:12:18 > 0:12:20So, would you like to hold the human brain?
0:12:21 > 0:12:24Who wants to halt the human brain. You do? Put your hands out.
0:12:26 > 0:12:29- What's the first thing you notice about it?- It's quite heavy.
0:12:29 > 0:12:33It extraordinarily heavy, isn't it? It's about one half pounds.
0:12:33 > 0:12:34You can pass it along.
0:12:34 > 0:12:36One and a half kilos, I should say. OK.
0:12:38 > 0:12:40It's really quite heavy.
0:12:40 > 0:12:42What else is it? What else do you notice about it?
0:12:42 > 0:12:44Let me tell you.
0:12:44 > 0:12:46Can I have my brain back? Thank you.
0:12:47 > 0:12:49The brain, as you can see,
0:12:49 > 0:12:53is made up of two halves and each half is called a hemisphere.
0:12:53 > 0:12:56The interesting thing about the hemisphere is it controls
0:12:56 > 0:12:59the opposite side of the body, so if you remember
0:12:59 > 0:13:01when we were stimulating Vince's brain
0:13:01 > 0:13:03with the trans-magnetic stimulator,
0:13:03 > 0:13:06when I was activating his left side of the brain,
0:13:06 > 0:13:10it was his right hand which was being affected.
0:13:10 > 0:13:13Now, we don't really know why the brain is organised like that.
0:13:13 > 0:13:15It's a little bit of a mystery.
0:13:15 > 0:13:17In fact, you probably wouldn't be aware
0:13:17 > 0:13:22unless you've got some damage on the opposite side and you noticed the behaviour was affected.
0:13:22 > 0:13:26The other thing about the brain which I think is quite fascinating
0:13:26 > 0:13:27is all these folds and creases
0:13:27 > 0:13:30because all brains have this to some extent
0:13:30 > 0:13:34but if you look at the example of the mouse brain or the rat brain,
0:13:34 > 0:13:36they're really quite smooth.
0:13:36 > 0:13:40In the human, these folds and creases are quite pronounced
0:13:40 > 0:13:41so why is that?
0:13:41 > 0:13:44To get an answer for that, you really have to zoom in
0:13:44 > 0:13:46to the building blocks of the brain
0:13:46 > 0:13:49to a special kind of cell called a neuron and here we have
0:13:49 > 0:13:52the image of a neuron and as you can see
0:13:52 > 0:13:55it looks like a kind of strange alien creature from outer space
0:13:55 > 0:13:57and there's a lot of them.
0:13:57 > 0:14:00There are about 100 billion neurons in the average brain.
0:14:00 > 0:14:03And all these tentacles are dendrites
0:14:03 > 0:14:06and this is the way neurons are communicating with each other,
0:14:06 > 0:14:09by sending electrical impulses.
0:14:09 > 0:14:12Each neuron typically has one very thick connecting fibre
0:14:12 > 0:14:15called the axon and it's the axon that sends out information
0:14:15 > 0:14:18to connect up with all the others.
0:14:18 > 0:14:21Now, it turns out that the neurons
0:14:21 > 0:14:24and the connections which are related to those things we consider
0:14:24 > 0:14:28intelligence and being clever, they're not throughout the brain.
0:14:28 > 0:14:31They're concentrated in just the outer layer of the brain,
0:14:31 > 0:14:35a layer that's only 3-4 millimetres thick.
0:14:35 > 0:14:36We call this the cortex.
0:14:36 > 0:14:40The cortex comes from the Latin word for bark.
0:14:40 > 0:14:44So it's this outer layer with all these connections which make us
0:14:44 > 0:14:47very clever and flexible in our thinking.
0:14:47 > 0:14:49So it's not so much the size of the brain that's important.
0:14:49 > 0:14:52Rather, it's the surface area of the cortex
0:14:52 > 0:14:56and how big that is that allows for all these connections.
0:14:56 > 0:14:59If you take the human brain and flatten it out,
0:14:59 > 0:15:01it would have this degree of surface area.
0:15:01 > 0:15:03Would you hold my brain for a moment?
0:15:03 > 0:15:07OK, so this is how big the human cortex is if you flatten it out.
0:15:07 > 0:15:13That's a very big area, so how do you get all that inside a normal head?
0:15:13 > 0:15:15Well, here's nature's solution.
0:15:16 > 0:15:17It's all folded up.
0:15:17 > 0:15:20So nature has come up with an answer
0:15:20 > 0:15:23for, basically, an engineering problem.
0:15:23 > 0:15:24Thank you very much.
0:15:26 > 0:15:30Now, if it wasn't all folded up like that,
0:15:30 > 0:15:33then your head would have to be half as big again, which is not a good look
0:15:33 > 0:15:36and, for any mothers watching, it's bad enough giving birth
0:15:36 > 0:15:40to a baby of a normal sized head without it being any larger.
0:15:40 > 0:15:45OK, so let's now consider some other animals. Look at these little guys.
0:15:47 > 0:15:49They're quite exotic, aren't they?
0:15:49 > 0:15:53Does anyone know what they are? They're jellyfish, that's right.
0:15:53 > 0:15:55They're Australian Blubber Jellyfish
0:15:55 > 0:15:59and you can see them moving around in the pool.
0:15:59 > 0:16:02So what's so special about the brain of a jellyfish?
0:16:02 > 0:16:03Would anyone like to answer?
0:16:03 > 0:16:06- Sir?- Is it transparent? - That's a good answer.
0:16:06 > 0:16:10- Anything else? Yes? - It doesn't have one?
0:16:10 > 0:16:12It doesn't have one. Well done.
0:16:12 > 0:16:15A trick question. They do have a central nervous system
0:16:15 > 0:16:18but they don't really have a brain as such.
0:16:18 > 0:16:20So if jellyfish don't have brains,
0:16:20 > 0:16:23then why do all these other animals have brains?
0:16:23 > 0:16:26Why do you think we have a brain in the first place?
0:16:26 > 0:16:28Who would like to answer? Yes.
0:16:28 > 0:16:30Because otherwise we wouldn't be alive?
0:16:30 > 0:16:33Otherwise we wouldn't be alive, that's good. Any more answers?
0:16:33 > 0:16:35- Yes?- Memory.
0:16:35 > 0:16:38These are all great answers but the basic answer for all the animals
0:16:38 > 0:16:43which have brains is that we use brains to navigate around the world.
0:16:43 > 0:16:44The jellyfish can move
0:16:44 > 0:16:47but it's not keeping track of where it's going and jellyfish
0:16:47 > 0:16:51tend to go with the ebb and flow of the tides whereas animals that have
0:16:51 > 0:16:55brains are using them to navigate their world, to find food,
0:16:55 > 0:16:56to seek mates, to avoid predators
0:16:56 > 0:16:59and to keep track of where they're going
0:16:59 > 0:17:01in order to plan their movements in the world.
0:17:01 > 0:17:05So brains are for figuring out and predicting what's going to go next.
0:17:05 > 0:17:08If you think about it, an animal, or an animal like us,
0:17:08 > 0:17:13is really a kind of complex mobile moving factory made up of many subdivisions,
0:17:13 > 0:17:16different processing plants, recycling centres
0:17:16 > 0:17:19and movement machinery, and that all has to be coordinated.
0:17:19 > 0:17:22If it wasn't, we'd fall apart
0:17:22 > 0:17:26so brains are really for controlling all these different activities.
0:17:26 > 0:17:29Now some of these activities are fairly automated.
0:17:29 > 0:17:32For example, breathing and hearts are controlled by the brainstem
0:17:32 > 0:17:36which is below the cortex, so it doesn't require a lot of consciousness.
0:17:36 > 0:17:41And other things like your movements that you've learnt well, you don't have to think about them.
0:17:41 > 0:17:46Even walking. You know where you're going and you can plan that, but coordinating the movements,
0:17:46 > 0:17:48you don't have to think about that.
0:17:48 > 0:17:51And that's controlled by the cerebellum at the bottom here.
0:17:51 > 0:17:53So whether they're automatic or controlled,
0:17:53 > 0:17:56the whole point is they still need to be coordinated by a system
0:17:56 > 0:17:59and that's what the cortex does, sitting up here.
0:17:59 > 0:18:01So the information is flooding up into the brain
0:18:01 > 0:18:03through the central nervous system.
0:18:03 > 0:18:07The information from the most extreme parts, for example the arms
0:18:07 > 0:18:12or even the legs, they form part of the peripheral nervous system.
0:18:12 > 0:18:14So how fast does a nerve impulse travel?
0:18:14 > 0:18:18Well, we're going to try a little experiment. We're going to measure the speed of a nerve impulse
0:18:18 > 0:18:22travelling the length of one arm and I'm going to need some volunteers.
0:18:22 > 0:18:27In fact, I'm going to need all of Row E, so stand up, row E.
0:18:27 > 0:18:29Big round of applause.
0:18:29 > 0:18:32APPLAUSE
0:18:36 > 0:18:39- What's your name, sir? - My name's Omar.- Omar?- Yep.
0:18:39 > 0:18:43- OK, Omar, and who do we have at the end?- Tim.- Hello, Tim.
0:18:43 > 0:18:47Omar, what I'm going to do is I'm going to grip your left shoulder with my right hand
0:18:47 > 0:18:50and with your right hand, you grip the left shoulder
0:18:50 > 0:18:52and everyone copy everyone so you form a chain reaction.
0:18:52 > 0:18:55OK. Are you all holding? Right.
0:18:55 > 0:19:00What I'm going to do is I'm going to squeeze your shoulder gently and everyone do it gently.
0:19:00 > 0:19:03When you feel your shoulder being squeezed, and not before,
0:19:03 > 0:19:07you squeeze your neighbour's shoulder, so it's going to pass the entire length of Row E.
0:19:07 > 0:19:10OK? And Tim at the end, when you feel your shoulder being squeezed,
0:19:10 > 0:19:14you shout stop because we're going to measure the speed,
0:19:14 > 0:19:18the time it takes for that response to travel the full length of Row E.
0:19:18 > 0:19:19You got it?
0:19:19 > 0:19:22So let's go.
0:19:24 > 0:19:28- Stop.- OK, that's pretty good. That's 3.10 seconds.
0:19:28 > 0:19:32Let's see if you can get a bit faster. All right, ready again?
0:19:36 > 0:19:41- Stop.- OK, that's just under three seconds. That's pretty good. You are getting better with practise.
0:19:41 > 0:19:44Now, this time I don't want you to grip the shoulder.
0:19:44 > 0:19:48I want you to hold hands. You should be even faster now, shouldn't you?
0:19:48 > 0:19:51Squeeze your neighbour's hand when you feel your left hand is squeezed
0:19:51 > 0:19:54and, again, Tim, you shout stop when you feel that.
0:19:54 > 0:19:55OK, ready?
0:19:59 > 0:20:00Stop.
0:20:00 > 0:20:05That's three seconds, almost a full second longer.
0:20:05 > 0:20:09Now, why does it take longer for the nerve impulse to travel the full distance?
0:20:09 > 0:20:11If you think about it, the first time we did it
0:20:11 > 0:20:14it's only travelling the length of one arm.
0:20:14 > 0:20:15But when we're holding hands,
0:20:15 > 0:20:20it has to travel the length of one arm plus an extra arm to the person next to you.
0:20:20 > 0:20:23An arm is almost a metre long, isn't it?
0:20:23 > 0:20:27And with 15 arms, that's an extra 15 metres it has to travel
0:20:27 > 0:20:31in just under about a second, so it's somewhere between 10 and 15 metres per second,
0:20:31 > 0:20:33which is about right for that kind of nerve impulse.
0:20:33 > 0:20:35So, a big round of applause for row E.
0:20:35 > 0:20:39APPLAUSE
0:20:41 > 0:20:44So, we were estimating the speed of a nerve impulse in the arm,
0:20:44 > 0:20:47and it's usually roundabout that kind of speed,
0:20:47 > 0:20:50and that's usually a lot slower than people imagine,
0:20:50 > 0:20:53because when you think about nerve impulses we often assume
0:20:53 > 0:20:56they must be almost as fast as electricity,
0:20:56 > 0:20:58because it seems like it is an electrical impulse.
0:20:58 > 0:21:04But, in fact, electricity travels about three million times faster than a nerve impulse.
0:21:04 > 0:21:07So, we've been using these sorts of experiments to try
0:21:07 > 0:21:10and estimate how the brain is working,
0:21:10 > 0:21:13but can you ever really measure directly nerve activity?
0:21:13 > 0:21:17Remarkably, you can if you're an expert and you know what you're doing,
0:21:17 > 0:21:19and you happen to have a very thin wire.
0:21:19 > 0:21:22So, would you give a warm welcome to two experts from Newcastle,
0:21:22 > 0:21:25Dr Claire Rind and Dr Peter Simmons.
0:21:25 > 0:21:29APPLAUSE
0:21:35 > 0:21:39So, Claire, I believe you've had some interesting travelling
0:21:39 > 0:21:41companions with you, is that right?
0:21:41 > 0:21:44We have, we've come down on the train with a box full of locusts.
0:21:44 > 0:21:48Oh, right. So these are live locusts?
0:21:48 > 0:21:51Yes, they're all munching on the grass,
0:21:51 > 0:21:54there's about six of them in there, varying sizes.
0:21:54 > 0:21:57So he's gently being placed on his back, is that right?
0:21:57 > 0:22:02Yes, in a little bed of Plasticine - it's actually a she -
0:22:02 > 0:22:05lying on her back in a bed of Plasticine
0:22:05 > 0:22:10and we've restrained the animal with little loops of Plasticine,
0:22:10 > 0:22:15and Peter is putting a very fine wire into its chest.
0:22:15 > 0:22:19The wire is rather like an acupuncture wire, very fine,
0:22:19 > 0:22:23- just a small diameter wire.- So it doesn't hurt the locust at all?
0:22:23 > 0:22:25- No, not at all.- That's amazing.
0:22:25 > 0:22:29Whilst Peter is setting up, because this is a very delicate procedure,
0:22:29 > 0:22:32let me tell you a little bit about the locust.
0:22:32 > 0:22:36The locust is really a giant kind of grasshopper, and it has this
0:22:36 > 0:22:40very simple nervous system for avoiding bumping into things.
0:22:40 > 0:22:42The reason it needs to do this is
0:22:42 > 0:22:46because when they get large in numbers they can become swarms,
0:22:46 > 0:22:48which are travelling in their vast numbers,
0:22:48 > 0:22:50and there's literally millions of them,
0:22:50 > 0:22:53and they can fly without bumping into each other.
0:22:53 > 0:22:57Swarms can be a real problem, because when they land on a crop
0:22:57 > 0:23:00they'll just ravish a crop and eat it within minutes.
0:23:00 > 0:23:02So, they are usually a pest to humans,
0:23:02 > 0:23:08but they've also been very helpful because we can measure their brain activity without hurting them.
0:23:08 > 0:23:11This is what you've been doing in your research, is that right?
0:23:11 > 0:23:15Yes, we've been looking at particular nerve cells
0:23:15 > 0:23:19within its nervous system and using this recording equipment
0:23:19 > 0:23:23to record electrical activity that the nerve cells make.
0:23:23 > 0:23:27In fact, the noise that you'll hear eventually is from
0:23:27 > 0:23:31a single nerve cell within the locust's nerve system.
0:23:31 > 0:23:33It's a very important neuron,
0:23:33 > 0:23:38one of the biggest in the body of the locust,
0:23:38 > 0:23:40and it communicates down to the wings
0:23:40 > 0:23:43and can actually shut off the flight cycle
0:23:43 > 0:23:47so that the locust will make a dive and avoid a predator
0:23:47 > 0:23:51or adjust its flight to avoid another member of the swarm.
0:23:51 > 0:23:53OK, so, Peter, are we ready?
0:23:53 > 0:23:56We're ready, I think she's ready, as well.
0:23:56 > 0:24:00I couldn't tell the difference, but I presume they're larger, the females?
0:24:00 > 0:24:02The female's larger, yes.
0:24:02 > 0:24:06OK, so which part of the visual field are we going to be recording from?
0:24:06 > 0:24:09We're recording from the right side of the locust,
0:24:09 > 0:24:13but it's the eye that is looking towards the left,
0:24:13 > 0:24:16she's on her back, so she's watching you.
0:24:16 > 0:24:18- She's watching me now? - She's watching you now.
0:24:18 > 0:24:23- Right, so we're going to listen in to her responding to me, is that correct?- Yes.
0:24:23 > 0:24:26Let's have some silence, listen very carefully,
0:24:26 > 0:24:30what you'll be hearing is the activity of the neurons.
0:24:30 > 0:24:35STATIC CRACKLING IN TIME WITH HAND MOVEMENTS
0:24:35 > 0:24:36Can you hear that?
0:24:39 > 0:24:44Do you realise you are listening to the brain of a locust?
0:24:44 > 0:24:50We know it's from that side because if I come from the other side...
0:24:53 > 0:24:54..you don't get the effect.
0:24:54 > 0:25:00Whereas, actually, I think she's paying quite a lot of attention to me now, isn't she?
0:25:02 > 0:25:06That is absolutely fascinating. Shall we try with this?
0:25:06 > 0:25:10This represents another large locust flying in the swarm towards it.
0:25:10 > 0:25:14RYTHMIC CRACKLING
0:25:14 > 0:25:16That's great.
0:25:16 > 0:25:19So, tell me, Claire, with this research what have you been able to do?
0:25:19 > 0:25:22Does it have any application for humans at all?
0:25:22 > 0:25:25It's a fascinating circuit the locust has and we've built
0:25:25 > 0:25:31an artificial circuit that we've been able to put into a sensor
0:25:31 > 0:25:34that is used for collision avoidance in cars,
0:25:34 > 0:25:38so we're hoping in the future that the circuits based on the locust
0:25:38 > 0:25:43will be able to help drivers avoid collisions in traffic.
0:25:43 > 0:25:47So, the locust insect is helping humans to avoid pileups on the M1?
0:25:47 > 0:25:49Eventually, that's what we think.
0:25:49 > 0:25:51Well, I think that's very useful.
0:25:51 > 0:25:54Can you release the locust to just show everything is fine with her?
0:25:56 > 0:25:59Can we get a close-up of the locust, just to show you?
0:25:59 > 0:26:02We can't let go because if she gets the chance she'll run away.
0:26:02 > 0:26:05You can see there she's perfectly OK.
0:26:05 > 0:26:08- And she bit me.- That's revenge, she's getting her own back, Peter.
0:26:08 > 0:26:12Let's put her back with her friends and let them go.
0:26:12 > 0:26:15Can we have a big round of applause for the locust...
0:26:15 > 0:26:16APPLAUSE
0:26:16 > 0:26:20...and Peter and Claire. Thank you so much for coming down.
0:26:27 > 0:26:29That was fascinating,
0:26:29 > 0:26:31but can we ever do the same thing for a human?
0:26:31 > 0:26:34Well, we chose a volunteer earlier, and this is Billy.
0:26:34 > 0:26:38He can't talk to us at the moment because we have him wired up.
0:26:38 > 0:26:41We're not sticking an electrode in his brain,
0:26:41 > 0:26:45rather we're recording from the outside, because it turns out
0:26:45 > 0:26:48that, if you have lots of neurons firing, they generate enough
0:26:48 > 0:26:51electrical activity that we can detect it with tiny electrodes.
0:26:51 > 0:26:55Normally when scientists do this, they have lots of electrodes,
0:26:55 > 0:27:00but for tonight's purposes we're just interested in the back of Billy's head,
0:27:00 > 0:27:02because this is where his visual area is,
0:27:02 > 0:27:04the visual cortex in the human.
0:27:04 > 0:27:08So, as before, we saw the locust was looking at a human - me -
0:27:08 > 0:27:11approaching the locust, this time we're presenting a locust
0:27:11 > 0:27:13to a human to see how they respond.
0:27:13 > 0:27:16And here we see this big pattern starting to build up.
0:27:16 > 0:27:21This is the response of Billy's visual area. Thank you, Kate.
0:27:21 > 0:27:25As you can see, as the locust was coming on it was responding,
0:27:25 > 0:27:29so the picture of the locust was generating activity in his eyes,
0:27:29 > 0:27:31then sending these impulses along the optic fibre
0:27:31 > 0:27:36to the back of the brain where the visual processing area is, then responding to that.
0:27:36 > 0:27:40That's the onset of the pattern, when the locust first appears,
0:27:40 > 0:27:43and this is the rest of the brainwave, showing how he processes it.
0:27:43 > 0:27:45So, Billy, it turns out that you do have a brain,
0:27:45 > 0:27:50so thank you very much and a big round of applause to Kate and Billy.
0:27:50 > 0:27:53APPLAUSE AND CHEERING
0:27:53 > 0:27:58Animals might be all moving and interacting in the same environment,
0:27:58 > 0:28:02like the locusts and humans, but their brains are very different,
0:28:02 > 0:28:05and what they're experiencing must be different.
0:28:05 > 0:28:09And even our own experience is often not what it seems.
0:28:09 > 0:28:11So, consider vision again.
0:28:11 > 0:28:15Most of us think that vision is rich and full of detail -
0:28:15 > 0:28:18in fact, a lot of us think it's almost like a camera, but is it really?
0:28:18 > 0:28:22Let's test that idea out. Joe, would you come in here?
0:28:22 > 0:28:26Joe's got a camera on his shoulder and he's taking the image
0:28:26 > 0:28:29and you can see that the image is projected above me
0:28:29 > 0:28:31and it's nice and rich and full of detail.
0:28:31 > 0:28:34This is what we think vision is really like,
0:28:34 > 0:28:37but, actually, human vision isn't like that at all,
0:28:37 > 0:28:40because we know from the studies using these techniques
0:28:40 > 0:28:43you're only ever processing the centre part of your vision,
0:28:43 > 0:28:46and in fact it's about the size of your thumb held at arm's length.
0:28:46 > 0:28:50So, can we make the camera appear like human vision?
0:28:50 > 0:28:52Now you can see it's all blurred at the edge
0:28:52 > 0:28:56and it's only the central part of the field which is clear and detailed.
0:28:56 > 0:29:01That's a bit strange, because that's not the way you experience vision, do you?
0:29:01 > 0:29:03You see it as full and complex.
0:29:03 > 0:29:07So, why is that? Well, let me show you.
0:29:07 > 0:29:09If I move a bit closer...
0:29:09 > 0:29:12the way that it seems more detailed is, of course,
0:29:12 > 0:29:15I simply move my eyes around.
0:29:15 > 0:29:20And I'm moving them quite rapidly, about four or five times per second.
0:29:20 > 0:29:21These are called saccades.
0:29:21 > 0:29:24This is how the brain builds up a picture of complexity,
0:29:24 > 0:29:26because you're sampling the world
0:29:26 > 0:29:30then storing that information, and the brain is remembering it,
0:29:30 > 0:29:33and this is what makes the world seem much more complex.
0:29:33 > 0:29:35There's a problem, though,
0:29:35 > 0:29:38because if a camera was to move like human vision,
0:29:38 > 0:29:41there'd be a real distortion, so let's take that away.
0:29:41 > 0:29:44Joe, can you move your camera like an eye movement?
0:29:44 > 0:29:46Let's see what that looks like.
0:29:55 > 0:29:59Now, what's wrong with that? Any suggestions? Yes.
0:29:59 > 0:30:01- AUDIENCE MEMBER:- It's kind of moving quite fast.
0:30:01 > 0:30:04It's very jerky, isn't it? It's very blurred.
0:30:04 > 0:30:07If that was your normal vision it'd make you very seasick,
0:30:07 > 0:30:10so your brain does a very clever trick.
0:30:10 > 0:30:14Every time you move your eyes it cuts out the visual information,
0:30:14 > 0:30:17so you don't see all those jerky, smeared, blurred images.
0:30:17 > 0:30:21So, Joe, can you simulate that, can you turn off the visual signal
0:30:21 > 0:30:23every time you're moving the camera?
0:30:29 > 0:30:35OK, your brain is literally cutting off all the visual information, in fact you can't see anything.
0:30:35 > 0:30:39We know that's true, I'm going to prove it and I'll need a volunteer.
0:30:39 > 0:30:42Let's see who we can choose. Do we have anyone? Young lady.
0:30:42 > 0:30:44- What's your name?- Amy.
0:30:44 > 0:30:47Amy, OK, would you hold the mirror like this, OK?
0:30:47 > 0:30:49Josh, can you pick up Amy? Good.
0:30:49 > 0:30:52Now, Amy, have a look at your left eye.
0:30:52 > 0:30:54Now look at your right eye.
0:30:54 > 0:30:56Swap backwards and forwards.
0:30:56 > 0:31:00- Can you see your eyes moving?- No.
0:31:01 > 0:31:04Can you see your eyes moving at all?
0:31:04 > 0:31:06- Can anyone else see her eyes moving? - AUDIENCE:- Yes.
0:31:06 > 0:31:10Amy, your eyes are moving, would you like me to prove it to you?
0:31:10 > 0:31:12Have a look up there.
0:31:12 > 0:31:14Ready?
0:31:17 > 0:31:19LAUGHTER
0:31:19 > 0:31:22It would seem like you're surprised, but don't worry,
0:31:22 > 0:31:25you're perfectly normal, you can't see your own eyes moving at all.
0:31:25 > 0:31:28Applause for Amy, please.
0:31:28 > 0:31:31APPLAUSE
0:31:33 > 0:31:36Now, you can try that all at home, actually.
0:31:36 > 0:31:39If you're brushing your teeth, just look in the mirror
0:31:39 > 0:31:42then focus on your left eye and shift to your right eye,
0:31:42 > 0:31:45see if you can see your eyes moving, and you won't be able to,
0:31:45 > 0:31:48because, no matter how you try, your brain is making you blind.
0:31:48 > 0:31:54Effectively, if you add up all the gaps - you're moving your eyes all the time when you're awake -
0:31:54 > 0:31:59you're blind for about two hours of the day, and you never even know that. Isn't that remarkable?
0:31:59 > 0:32:03Clearly the mind has amazing tricks that keep the world looking
0:32:03 > 0:32:06rich and full of detail and information.
0:32:06 > 0:32:09So, what happens to all that information once you've detected it?
0:32:09 > 0:32:12Ice creams! Get your ice creams here! Ice creams!
0:32:12 > 0:32:16Ah, here's some rich information - an ice cream. Thank you very much.
0:32:16 > 0:32:22So, consider an ice cream. It's full of lots of information.
0:32:22 > 0:32:27It looks delicious, it smells delicious, I'm going to do this...
0:32:28 > 0:32:34You can hear the crunch, it's cold, and it tastes very yummy,
0:32:34 > 0:32:38but somehow my brain combines all these different sensations
0:32:38 > 0:32:41into one experience a delicious ice cream.
0:32:41 > 0:32:42How does it do that?
0:32:42 > 0:32:48I'm going to show you by building a very simple brain in this auditorium.
0:32:48 > 0:32:52OK, we had some helmets given out earlier, so pop your helmets on.
0:32:52 > 0:32:56Those with the helmets, would you mind standing up?
0:32:56 > 0:32:58these are our volunteers.
0:32:58 > 0:33:01You're going to represent different groups of neurons.
0:33:01 > 0:33:05Let's say this part of the brain is coding for shapes.
0:33:05 > 0:33:08Sir, at the back, you code for anything which is round.
0:33:08 > 0:33:11And you in the front code for anything which is long, like a pencil.
0:33:11 > 0:33:15This part of the audience will represent the part of the brain
0:33:15 > 0:33:18which codes for colour, so you're going to be green,
0:33:18 > 0:33:21and you're going to respond to anything that's yellow.
0:33:21 > 0:33:24And over here we have a part of the brain which codes for taste,
0:33:24 > 0:33:28so you're getting information from the mouth, and you at the back,
0:33:28 > 0:33:31you're going to be sweet and you're going to be salty.
0:33:31 > 0:33:35Now hold-up these connections, because these are going to stand
0:33:35 > 0:33:40for all the connections between the different regions of the brain.
0:33:40 > 0:33:44Now press your buttons and let's see all the activity in the brain sending signals.
0:33:44 > 0:33:47You can flash them, let's see a lot of random connections.
0:33:47 > 0:33:51So here's our simple brain. How does a simple brain learn about objects?
0:33:51 > 0:33:54Well, we're going to teach it to learn about fruit.
0:33:54 > 0:33:58OK, so pop your lights off for a moment.
0:33:58 > 0:34:01Now, imagine that you've never eaten a banana before.
0:34:01 > 0:34:05So, let's have you responding, if your feature's present, hold down your button.
0:34:05 > 0:34:07Let's see what that looks like.
0:34:07 > 0:34:09So it's long, it's yellow,
0:34:09 > 0:34:12and you pop it in your mouth and what does it taste like? Sweet.
0:34:12 > 0:34:15Sweet. So that's the pattern for a banana.
0:34:15 > 0:34:19All right, now everyone switch your lights on again,
0:34:19 > 0:34:23communicating again, there it's talking to itself, and put them off.
0:34:23 > 0:34:26Let's come across another fruit.
0:34:26 > 0:34:29This time, it's round, hold it down...
0:34:29 > 0:34:31it's green...
0:34:31 > 0:34:34and you pop it into your mouth and it's sweet.
0:34:36 > 0:34:39And every time you eat a banana, or a grape,
0:34:39 > 0:34:41that pattern becomes stronger.
0:34:41 > 0:34:45This is because the neurons that fire together are wiring together.
0:34:45 > 0:34:50Now, you might notice how the banana and the grape
0:34:50 > 0:34:53are activating the same part, which is the sweet centres.
0:34:53 > 0:34:56That shows you the brain can reuse the same regions
0:34:56 > 0:34:57to code for different objects.
0:34:57 > 0:35:01So, what happens when you go to a new part of the world
0:35:01 > 0:35:04and encounter new food you've never had before?
0:35:04 > 0:35:06Turn your lights off for a moment.
0:35:06 > 0:35:08Let's say you go to the Mediterranean
0:35:08 > 0:35:11and you see this small, round, green thing.
0:35:11 > 0:35:15So it's round, it's green, and your brain thinks,
0:35:15 > 0:35:18"Well, it looks like a grape, so it's going to be sweet."
0:35:18 > 0:35:20So, sweet, pop your light on.
0:35:20 > 0:35:23But then when you pop it into your mouth...
0:35:23 > 0:35:26Yuck! It's salty!
0:35:26 > 0:35:28So, this is why you can be very surprised
0:35:28 > 0:35:31when you encounter something new which seems so familiar.
0:35:31 > 0:35:35That's why new foods can surprise you.
0:35:35 > 0:35:38Let's consider our simple brain again.
0:35:38 > 0:35:41If I show you this pattern...
0:35:41 > 0:35:45Tell us, audience, what do you think that stands for, that pattern?
0:35:45 > 0:35:47AUDIENCE: Banana.
0:35:47 > 0:35:51It stands for banana, but it's not really a banana, is it?
0:35:51 > 0:35:54It's just how the brain recreates the sensation of eating bananas.
0:35:54 > 0:35:57It's what we call a representation,
0:35:57 > 0:36:01because the brain is re-presenting the original experience.
0:36:01 > 0:36:04Representations are really the language of the brain.
0:36:04 > 0:36:09Now, I have given you a very simple demonstration with only a few groups of neurons,
0:36:09 > 0:36:11just to give you an idea of different patterns,
0:36:11 > 0:36:13but the brain is much more complex.
0:36:13 > 0:36:17If this were a real brain, there'd be 100 billion neurons,
0:36:17 > 0:36:20and you wouldn't just be holding a couple of connections,
0:36:20 > 0:36:24because the neurons have up to 10,000 connections between them,
0:36:24 > 0:36:26and if you add up all the connections end to end,
0:36:26 > 0:36:30that stretches to 180,000 kilometres,
0:36:30 > 0:36:33and that's long enough to stretch around the world four times.
0:36:33 > 0:36:35That's rather mind blowing, isn't it?
0:36:35 > 0:36:38Because it means your brain has the capacity to encode an almost
0:36:38 > 0:36:42infinite number of patterns, which is why we say the human brain
0:36:42 > 0:36:45is the most complex structure to be found in nature.
0:36:45 > 0:36:49So, let's have a big round of applause for our small brain.
0:36:49 > 0:36:53APPLAUSE
0:36:54 > 0:36:59So, our world is full of rich experiences that are combined into these meaningful patterns,
0:36:59 > 0:37:03and these representations reflect all the structure and order
0:37:03 > 0:37:08that we encounter on a regular basis in our existence, in our lives.
0:37:08 > 0:37:11So, for example, if I have this garbage lid,
0:37:11 > 0:37:14you're processing this in different parts of your brain.
0:37:14 > 0:37:17You have a areas which are processing the vision,
0:37:17 > 0:37:19and if I drop it...
0:37:19 > 0:37:22you have areas of your brain processing the sound.
0:37:22 > 0:37:25So your visual area's active, and so are your sound areas.
0:37:25 > 0:37:30In fact, you've got a set of neurons which combine that experience of sight and sound.
0:37:30 > 0:37:33This representation of sight and sound is usually quite reliable,
0:37:33 > 0:37:36because sights usually go with sounds, but sometimes
0:37:36 > 0:37:40it can lead you to some false and surprising conclusions.
0:37:42 > 0:37:45BELCHING SOUNDS
0:37:45 > 0:37:48Let's try that one more time.
0:37:48 > 0:37:50BELCHING SOUNDS
0:37:50 > 0:37:54So, what you're doing there is you think that the skull is burping,
0:37:54 > 0:37:57but of course he isn't really, what's happening
0:37:57 > 0:38:01is you're seeing the skull move and you're hearing the sound
0:38:01 > 0:38:04and your brain's readily putting those things together.
0:38:04 > 0:38:06This is called the ventriloquist effect.
0:38:06 > 0:38:10And so, when people see ventriloquists they think they're throwing their voice,
0:38:10 > 0:38:13but they're not really throwing their voice,
0:38:13 > 0:38:16they're minimising the movement of their own mouths,
0:38:16 > 0:38:19making a sound, and exaggerating the mouth of the puppet.
0:38:19 > 0:38:22I can do that for a little bit, let's see if I can try
0:38:22 > 0:38:24and convince you this skull is talking,
0:38:24 > 0:38:29So if I go, she sells seashells on the seashore.
0:38:29 > 0:38:30OK.
0:38:30 > 0:38:35Not only does a ventriloquist shape where you think a sound's coming from,
0:38:35 > 0:38:38because sights and sounds usually come from the same place,
0:38:38 > 0:38:42the ventriloquist effect can also influence what you're hearing.
0:38:42 > 0:38:45So, in this next example, I want you to watch very carefully
0:38:45 > 0:38:49this little bit of video and see if you can hear what I'm saying.
0:38:51 > 0:38:55REPEATS EITHER "BA-BA! OR "DA-DA"
0:38:55 > 0:38:57What did you hear?
0:38:57 > 0:39:00AUDIENCE GIVES A MIXED RESPONSE
0:39:00 > 0:39:03Who heard "da-da", put your hand up?
0:39:03 > 0:39:06OK, everybody sitting in the middle. Let's try it again.
0:39:06 > 0:39:10REPEATS EITHER 'BA-BA' OR 'DA-DA'
0:39:10 > 0:39:12What do you hear? "Da-da?"
0:39:12 > 0:39:14Middle section only, what did you hear?
0:39:14 > 0:39:16"Da?" "Ba?"
0:39:16 > 0:39:18MIXED RESPONSE
0:39:18 > 0:39:20All right, let's make this easier.
0:39:20 > 0:39:24I want you to listen again, but close your eyes, OK?
0:39:26 > 0:39:30REPEATS EITHER "BA-BA" OR "DA-DA"
0:39:30 > 0:39:32What did you hear this time?
0:39:32 > 0:39:33AUDIENCE: "Ba".
0:39:33 > 0:39:34Definitely it was "Ba".
0:39:34 > 0:39:39If you heard "da" you were being fooled by an illusion called the McGurk effect,
0:39:39 > 0:39:42because I'm not actually mouthing "ba-ba" or "da-da",
0:39:42 > 0:39:45what I'm mouthing is "ga-ga".
0:39:45 > 0:39:48So the brain gets the signal of "ga", and it's hearing "ba",
0:39:48 > 0:39:51but these are patterns it's never encountered before,
0:39:51 > 0:39:54and it comes up with a solution which is "da".
0:39:54 > 0:39:58So your brain's always trying to interpret experiences
0:39:58 > 0:40:00to come up with the best solution.
0:40:00 > 0:40:03Now, this way when you're watching people speak,
0:40:03 > 0:40:06you watch their mouths moving and the shape of their mouths
0:40:06 > 0:40:08can influence what you think you're hearing.
0:40:08 > 0:40:10Here's a very simple party trick -
0:40:10 > 0:40:13I want you to turn to the person next to you
0:40:13 > 0:40:17and mouth the words "elephant juice". Don't say it, just mouth it.
0:40:17 > 0:40:19Turn to the person next to you.
0:40:23 > 0:40:27What does it sound like? What do you think the person might be saying?
0:40:27 > 0:40:30Why are you laughing?
0:40:30 > 0:40:32OK, OK.
0:40:32 > 0:40:35Does it look like they could be saying "I love you"?
0:40:35 > 0:40:37Do I hear "I love you"?
0:40:37 > 0:40:40I love you all, wouldn't the world be a greater place
0:40:40 > 0:40:45if everyone said "elephant juice" a little more often to each other?
0:40:45 > 0:40:50OK, so your brain is not just forming representations
0:40:50 > 0:40:55of the outside world, it's also storing these representations of your own bodies,
0:40:55 > 0:40:59and so for this next demonstration I'm going to require someone
0:40:59 > 0:41:01who doesn't mind losing their hand.
0:41:02 > 0:41:06Lady on the end here, why don't you come down?
0:41:06 > 0:41:10APPLAUSE
0:41:10 > 0:41:14It's all right, just there. What's your name, first of all?
0:41:14 > 0:41:18- Josie.- Josie, so you're quite prepared to lose your hand
0:41:18 > 0:41:22for medical science, is that correct? You don't mind losing a hand?
0:41:22 > 0:41:24Don't worry, I'm not going to remove your hand,
0:41:24 > 0:41:28I'm going to create the illusion that you're losing your hand.
0:41:28 > 0:41:31So, for this I need you to put on this very strange jacket.
0:41:31 > 0:41:33It's actually got three arms.
0:41:33 > 0:41:37OK, so put your arm through that one, then through the other one.
0:41:37 > 0:41:39That's the regular part of the jacket.
0:41:39 > 0:41:42Is that going to be a bit small for you? Perfect.
0:41:42 > 0:41:46- Now, we're going to torture you. OK, so now, Josie, did you say?- Yes.
0:41:46 > 0:41:49OK, Josie, take a seat. I want you to put your other hand
0:41:49 > 0:41:52up here, your left hand, both hands are there.
0:41:52 > 0:41:55OK, now, that looks a little bit strange,
0:41:55 > 0:41:59but I want you just to focus on this, this is a rubber hand.
0:41:59 > 0:42:02It's about the same size as Josie's hand, and I want you
0:42:02 > 0:42:05not to look at the audience, just concentrate on the hand, OK?
0:42:05 > 0:42:09This illusion takes about a minute or two to form.
0:42:09 > 0:42:13What should happen is that Josie is looking at this hand of hers,
0:42:13 > 0:42:16and it's in the same place her normal hand is.
0:42:16 > 0:42:22So, her brain is a little bit confused, because that hand should belong to her.
0:42:22 > 0:42:25At the same time, to make the illusion even more strong,
0:42:25 > 0:42:28Kate is simultaneously stroking the hands,
0:42:28 > 0:42:32so the brain is now receiving all this touch information.
0:42:32 > 0:42:36Again, it's combining information, trying to make sense of it.
0:42:36 > 0:42:39- How does that feel? - It feels really weird.
0:42:39 > 0:42:42- Does it feel very weird?- Yeah. - OK.
0:42:42 > 0:42:44So, just keep doing that for a moment.
0:42:49 > 0:42:53Now just keep focusing on the hand, OK?
0:42:53 > 0:42:54Ready?
0:42:55 > 0:42:58Did you get a strange... Did that feel a bit odd?
0:42:58 > 0:43:00OK, don't worry, I wasn't going to hurt your hand.
0:43:00 > 0:43:02Round of applause.
0:43:02 > 0:43:06APPLAUSE
0:43:10 > 0:43:12Thank you very much. Well done.
0:43:12 > 0:43:15Now, the reason that happened is because the brain wasn't
0:43:15 > 0:43:18exactly sure whether it was the rubber hand any more,
0:43:18 > 0:43:22and that's why most people you do that experiment with get this surprise.
0:43:22 > 0:43:26I can't bring you all down to try the rubber hand illusion,
0:43:26 > 0:43:28but I can show you a similar experience,
0:43:28 > 0:43:31so I'll need another volunteer, someone from this side.
0:43:31 > 0:43:33Young lady in the blue, why don't you come down?
0:43:35 > 0:43:38APPLAUSE
0:43:38 > 0:43:40- What's your name?- Charlotte.
0:43:40 > 0:43:44OK, Charlotte, here's a very simple way to induce the rubber hand illusion.
0:43:44 > 0:43:46I'm just going to turn you this way for a bit.
0:43:46 > 0:43:49There you go, Charlotte. Now put up your right hand.
0:43:49 > 0:43:51OK.
0:43:51 > 0:43:55Now, with your other hand just grip like this.
0:43:55 > 0:44:00Now, looking at your index finger, just move your fingers up and down whilst you're doing it.
0:44:00 > 0:44:03- Does that feel a little strange? You can all try this.- Yes.
0:44:03 > 0:44:06Just turn to the person next to you.
0:44:06 > 0:44:10With your thumb and forefinger see if you can do this.
0:44:12 > 0:44:15It's strange, isn't it? It is very, very weird.
0:44:15 > 0:44:18You can try it at home as well, if you like.
0:44:24 > 0:44:27All right, guys, let's settle down.
0:44:27 > 0:44:30Let's give a round of applause to Charlotte.
0:44:30 > 0:44:34- APPLAUSE - Thank you, Charlotte.
0:44:38 > 0:44:41So, your brain is always trying to make sense of the world.
0:44:41 > 0:44:46Sometimes, when it gets strange signals, it comes up with strange experiences and illusions.
0:44:46 > 0:44:53We see things all the time. It might be faces in a cloud or animals in ink stains.
0:44:53 > 0:44:55Just simple coffee beans.
0:44:55 > 0:45:01If I scatter them onto here, you can see all sorts of patterns in that.
0:45:01 > 0:45:05Can anyone see a pattern forming there at all?
0:45:05 > 0:45:07Shout if you see anything.
0:45:07 > 0:45:09There's a mouse?
0:45:09 > 0:45:12SHOUTING FROM AUDIENCE
0:45:12 > 0:45:13What else?
0:45:15 > 0:45:16Oh...
0:45:16 > 0:45:19AUDIENCE SHOUTS
0:45:19 > 0:45:20OK.
0:45:22 > 0:45:27So, you're all seeing lots of patterns. That's very good.
0:45:27 > 0:45:31OK. Clearly you're all seeing lots of things. That's very reassuring.
0:45:31 > 0:45:34Your brain always tries to impose structure and order.
0:45:34 > 0:45:38This is most obvious with certain types of illusions
0:45:38 > 0:45:42where you have patterns which can be seen in more than one way.
0:45:42 > 0:45:46Probably one of the most famous examples is called The Necker Cube.
0:45:46 > 0:45:48Here is a Necker Cube.
0:45:48 > 0:45:53It is an outline of a cube. If you look at it long enough, you think it's pointing in one direction
0:45:53 > 0:45:57but then, if you stare at it long enough, your brain switches
0:45:57 > 0:46:01and it appears to be in the opposite direction.
0:46:01 > 0:46:03Is anyone having that experience? Hands up.
0:46:03 > 0:46:05That's great.
0:46:05 > 0:46:07We can make it stronger if we put a bit of movement into it.
0:46:07 > 0:46:11So just watch as it turns.
0:46:11 > 0:46:18It seems to be going in one direction. Then, is anyone getting it turning in the other direction?
0:46:18 > 0:46:23Yeah? Just watch. You know what makes it really good?
0:46:23 > 0:46:26If you blink, while you're watching, you'll see it switch.
0:46:26 > 0:46:30We're not using any computer trickery here.
0:46:30 > 0:46:34It's simply your brain switching from one version versus the other.
0:46:36 > 0:46:38Isn't that remarkable?
0:46:38 > 0:46:40AUDIENCE MURMURS
0:46:40 > 0:46:42Here is another interesting point.
0:46:42 > 0:46:47Your brain doesn't allow you to see all the patterns at once.
0:46:47 > 0:46:50It forces you into one perception versus the other.
0:46:50 > 0:46:56This might explain why some of you sometimes see things like ghosts, for example.
0:46:56 > 0:47:00I am going to conjure up a ghost in front of your very eyes, OK?
0:47:00 > 0:47:06Don't worry, it won't be a headless horseman. It'll be more simple and friendly than that.
0:47:06 > 0:47:07All you need for this,
0:47:07 > 0:47:11and you can try this at home, are just four circles of paper.
0:47:11 > 0:47:14It's such a simple illusion but it's very compelling.
0:47:18 > 0:47:22All I have to do his cut a quarter of the circle.
0:47:29 > 0:47:32If you then align up the circles...
0:47:34 > 0:47:39..you will see something that isn't really there.
0:47:40 > 0:47:43What does anyone see? Hands up. Shout out.
0:47:43 > 0:47:46- AUDIENCE SHOUTS - That's right. A square.
0:47:46 > 0:47:49But, of course, there isn't a square there, is there?
0:47:49 > 0:47:53When I take this away it disappears and back it comes again.
0:47:53 > 0:47:57This is a very simple illusion, but it's also a very powerful one
0:47:57 > 0:48:02because I think it explains one of the most important points about the brain.
0:48:02 > 0:48:08If I went into the back of your brain with a wire, I could measure activity
0:48:08 > 0:48:12of neurons which are firing as if they're really was a square there.
0:48:12 > 0:48:18So this is remarkable - the brain is creating its own experience, isn't it?
0:48:18 > 0:48:23In fact, we can even show that you think this is a solid object.
0:48:23 > 0:48:25They've done this recently in an experiment
0:48:25 > 0:48:30where they've put people in a brain scanner and they've showed them this square.
0:48:30 > 0:48:32It's called the Kanizsa Illusion.
0:48:33 > 0:48:37Here we have the square. Then they made the square move.
0:48:39 > 0:48:43You see, it is travelling across.
0:48:43 > 0:48:47Watch as it moves across the screen.
0:48:50 > 0:48:53There it goes again. Undulating like a real object.
0:48:55 > 0:48:57Isn't that very bizarre?
0:48:59 > 0:49:03AUDIENCE MURMURS
0:49:03 > 0:49:08It's moving across the screen. See if we can move it a bit faster.
0:49:08 > 0:49:10There it goes, moving across the screen.
0:49:15 > 0:49:19What's remarkable is that the movement areas of the brain are being activated
0:49:19 > 0:49:24which are going in the same direction as the illusory ghostly square.
0:49:24 > 0:49:28So, your brain doesn't allow you to have contact with reality.
0:49:28 > 0:49:31It is generating reality the whole time.
0:49:31 > 0:49:33It is quite remarkable.
0:49:33 > 0:49:37Let us come back to Charlie and Iona, at the beginning.
0:49:37 > 0:49:40Let's get them back in for the rest of the show.
0:49:40 > 0:49:42Where are you? Come one down.
0:49:42 > 0:49:44A big round of applause, please.
0:49:44 > 0:49:47APPLAUSE
0:49:50 > 0:49:53- So, guys, how are you enjoying the show so far?- It is great.
0:49:53 > 0:49:55Reality hasn't changed for you. You're still very tall, Charlie,
0:49:55 > 0:50:01- and you're still A bit shorter, aren't you?- Yes.- Would you like to be taller than Charlie?- Yes.
0:50:01 > 0:50:05Well, with the RI Christmas show we can actually make that happen
0:50:05 > 0:50:08so please follow Kate out of the room for a moment.
0:50:08 > 0:50:11We will be seeing them very shortly.
0:50:11 > 0:50:17Throughout the lecture tonight, we've been watching how reality is created by the brain.
0:50:17 > 0:50:21And it uses past experiences to make sense of the world.
0:50:21 > 0:50:25But things are not always as they seem.
0:50:25 > 0:50:28Sometimes we can fool the...
0:50:28 > 0:50:30Oh! Hello, guys.
0:50:30 > 0:50:32There we go! Can you give a wave, Charlie.
0:50:32 > 0:50:36- Charlie, that room seems a bit small, doesn't it?- Yeah.
0:50:36 > 0:50:40Maybe you should try going to the opposite corner.
0:50:40 > 0:50:42- Iona, why don't you switch places? - OK.- OK.
0:50:44 > 0:50:49Oh, my gosh! How did that happen? Switch places again.
0:50:54 > 0:50:57Can you hold hands? Can you reach each other?
0:50:57 > 0:50:59There we go.
0:50:59 > 0:51:02Look, it's a giant and a smaller person.
0:51:03 > 0:51:07OK. You can have the bit of fun in there because I'll explain what's going on.
0:51:07 > 0:51:10To do that, I need a model.
0:51:10 > 0:51:13What you can't see is that's obviously not a normal room.
0:51:13 > 0:51:17In fact, the room has this sort of shape.
0:51:17 > 0:51:20It is just the way we have set the camera angle.
0:51:20 > 0:51:27What week doing is fooling and tricking your brain into thinking that is, in fact, a square room.
0:51:27 > 0:51:30I can illustrate this with the next example over here.
0:51:33 > 0:51:36Do these lines look equally long to you?
0:51:36 > 0:51:38AUDIENCE: Yes.
0:51:38 > 0:51:41The green lines? Who says they look the same?
0:51:41 > 0:51:45That is a very strange brain you have. The rest of you, I hope...
0:51:45 > 0:51:47Who things they look longer?
0:51:48 > 0:51:53That's great! Because, of course, it's an illusion.
0:51:53 > 0:51:55This is the Ponzo Illusion.
0:51:55 > 0:51:58In fact, the lines are exactly the same length.
0:52:00 > 0:52:02I'm going to make that big again.
0:52:02 > 0:52:08What is going on here is your brain has been fooled by what are called perspective cues.
0:52:08 > 0:52:10It's almost like it's on a railway track
0:52:10 > 0:52:15and because railway tracks recede off into the distance, they converge.
0:52:15 > 0:52:18Because this seems to be further away
0:52:18 > 0:52:22and it is stretching over the edge, we assume it must be much larger
0:52:22 > 0:52:25than this block which is sitting inside the tracks.
0:52:25 > 0:52:28Once again, even though your brain tells you that they look different
0:52:28 > 0:52:32in fact they are exactly the same length.
0:52:34 > 0:52:37So, at this is what is going on in the Ames Room.
0:52:37 > 0:52:41It uses these perspective cues of slanted lines to fool your brain
0:52:41 > 0:52:45into thinking that the room is actually the same distance.
0:52:45 > 0:52:47In fact, it is actually longer.
0:52:47 > 0:52:50I suppose the best way to show you how it will work is if I go out there
0:52:50 > 0:52:55and you can see what I am like and what the room is really like. OK?
0:53:00 > 0:53:03- Here we are at the Ames Room. How are you doing?- Fine.
0:53:03 > 0:53:04If you have a look a round,
0:53:04 > 0:53:07you can see that the room the room isn't straight or normal.
0:53:07 > 0:53:11It has slanting lines and the way the team have built it...
0:53:11 > 0:53:15when you shoot it from one angle it looks as if the perspective is correct,
0:53:15 > 0:53:18but in fact it is entirely wrong. Why don't you swap over again?
0:53:18 > 0:53:21In fact, I think I'll join you.
0:53:21 > 0:53:23So you can watch me going into the room
0:53:23 > 0:53:25and look how I transform in size. Here I come!
0:53:25 > 0:53:27So, I'm big.
0:53:30 > 0:53:34And now, Iona, you're bigger than both of us.
0:53:34 > 0:53:37So, that's part of the magic of the Royal Institution.
0:53:37 > 0:53:42Why don't you come back in and give a big round of applause for everyone?
0:53:42 > 0:53:44APPLAUSE
0:53:53 > 0:53:55So, all these illusions demonstrate
0:53:55 > 0:53:58our brains constantly try to make sense of the world
0:53:58 > 0:54:01and understand based on these stored representations.
0:54:01 > 0:54:04The remarkable thing about illusions is, even when you know how they work,
0:54:04 > 0:54:07and I've just demonstrated with the models and shown
0:54:07 > 0:54:11that these are illusions, you can't help but see them one way or the other.
0:54:11 > 0:54:14It's because your brain is creating your mind's experience.
0:54:14 > 0:54:15You can't avoid that.
0:54:15 > 0:54:19So, you remember I promised you we were going to look at Thalia's brain
0:54:19 > 0:54:24and read her mind? Let's go back to Cheltenham and see if we've made that link.
0:54:24 > 0:54:27Hello, Cheltenham, can you hear me at all?
0:54:27 > 0:54:30- It's Cheltenham here. Hi, London. - Is that Iain, is it?
0:54:30 > 0:54:32Yes, hi, Bruce, hi!
0:54:32 > 0:54:36Hi, hi! How's it been going? Have you managed to scan Thalia's brain?
0:54:36 > 0:54:38Yeah, we've got some great pictures. It looks good.
0:54:38 > 0:54:42Good. Can you send through the first image so we can get an idea of what you've got.
0:54:42 > 0:54:45- That's structural image, is that correct?- Yeah.
0:54:45 > 0:54:51So, I'm going to tell the audience, to give them an idea what they're looking at.
0:54:51 > 0:54:55Imagine I'm Thalia and I'm lying inside the scanner. Here I am.
0:54:55 > 0:55:00And so the scan is going from the bottom of my brain up to the top of my head.
0:55:00 > 0:55:05So this side of the screen is the right side of my brain, OK?
0:55:05 > 0:55:10This side of the image on this side of the screen is the left side of my brain.
0:55:10 > 0:55:16So, Iain, am I correct? Did you try showing Thalia a visual image earlier, is that right?
0:55:16 > 0:55:19Yes, we did. We showed her a visual object, yeah.
0:55:19 > 0:55:23Can you show us what the brain activation was like
0:55:23 > 0:55:26when she was looking at a visual object? OK.
0:55:26 > 0:55:30So, tell us, what part of the brain is that that's being activated?
0:55:30 > 0:55:35- The back.- So, if it's the back part of the brain, what's going on?
0:55:35 > 0:55:39- Which area's that?- Vision.- That's right. We showed Thalia a picture.
0:55:39 > 0:55:43When she looked at the picture, the back of her brain was more active.
0:55:43 > 0:55:45This was showing the functions of her brain working.
0:55:45 > 0:55:49Now, Thalia, we asked her to...
0:55:49 > 0:55:52we had a walnut and we asked her to put it in one of her hands.
0:55:52 > 0:55:54Have you been processing that image, Iain?
0:55:54 > 0:55:57Yes, we have. We've been processing the image.
0:55:57 > 0:56:02You say she had a walnut in one hand. We took some pictures while she was squeezing the walnut with her hand.
0:56:02 > 0:56:05Great. Have you got those images ready for us? OK.
0:56:05 > 0:56:10So, if that's the image, which side of the brain is more active? Which side of the image is it?
0:56:10 > 0:56:13- Right.- So, it's on the right side.
0:56:13 > 0:56:16This is the right side of my brain. What you've learned tonight
0:56:16 > 0:56:20about how things cross over, which hand is Thalia holding the walnut in?
0:56:20 > 0:56:26- Left!- Thalia, could you confirm to me which hand you were squeezing the walnut with?
0:56:26 > 0:56:29My left hand.
0:56:29 > 0:56:32Thank you.
0:56:33 > 0:56:36You have just mind read Thalia because you predicted which hand
0:56:36 > 0:56:41she was holding it in. Do you realise that's over 100 miles away?
0:56:41 > 0:56:43A big round of applause, everyone.
0:56:43 > 0:56:45APPLAUSE
0:56:53 > 0:56:57Before we go, can we say thank you and good night to Thalia and Iain? Good night, Cheltenham.
0:56:57 > 0:56:59Good night.
0:56:59 > 0:57:01So, that's what's inside your head.
0:57:01 > 0:57:06Your brain is interpreting the world around you into meaningful patterns
0:57:06 > 0:57:10and storing those patterns of representations. With these technologies
0:57:10 > 0:57:12we can read the activity of the brain.
0:57:12 > 0:57:16Does that mean, to know what's on someone's mind, we have to look at brain activity?
0:57:16 > 0:57:19The technologies are useful if you know what you're looking for
0:57:19 > 0:57:24and the tasks are very simple, like squeezing a walnut in one hand.
0:57:24 > 0:57:27But, the thing about humans is, we're very complicated.
0:57:27 > 0:57:29The tasks we can do are very difficult.
0:57:29 > 0:57:31That's what makes us human in many ways.
0:57:31 > 0:57:34So, that raises the question,
0:57:34 > 0:57:38who was coordinating all these difficult tasks and activities?
0:57:38 > 0:57:43Who is in charge anyway? We'll be addressing that in the next lecture.
0:57:43 > 0:57:46Good night and look after your brains. Good night.
0:57:46 > 0:57:50CHEERING AND APPLAUSE