0:00:02 > 0:00:04Who are we?
0:00:06 > 0:00:08What makes us tick?
0:00:10 > 0:00:12How do our minds work?
0:00:13 > 0:00:17For centuries, these questions were largely left
0:00:17 > 0:00:19to philosophers and theologians.
0:00:21 > 0:00:23Then, around 100 years ago,
0:00:23 > 0:00:28a new science opened a window on the inner workings of the mind.
0:00:28 > 0:00:31It was called experimental psychology.
0:00:36 > 0:00:40In this series, I will explore the history of how this new science
0:00:40 > 0:00:43revealed things about human nature that were surprising,
0:00:43 > 0:00:45and often profoundly shocking.
0:00:45 > 0:00:47ELECTRICAL CRACKLE
0:00:47 > 0:00:50- The experiment requires that we continue...- But he might be dead!
0:00:50 > 0:00:52Ever since I was a medical student,
0:00:52 > 0:00:56I have been fascinated by psychology, by its brutal history,
0:00:56 > 0:01:00and by how far some researchers have been prepared to go
0:01:00 > 0:01:02in the search for answers.
0:01:11 > 0:01:15This time, I'm investigating how studying the abnormal brain
0:01:15 > 0:01:20has shone a bright light on to the workings of the normal brain.
0:01:20 > 0:01:23It got totally out of control,
0:01:23 > 0:01:26he's smacking me and hitting me and pulling my hair out.
0:01:28 > 0:01:31When the brain is damaged by natural causes,
0:01:31 > 0:01:33or by operations that go wrong,
0:01:33 > 0:01:37the bizarre symptoms that sometimes then result
0:01:37 > 0:01:40are often extremely illuminating.
0:01:42 > 0:01:44< Can you tell me that number?
0:01:44 > 0:01:45Five. >
0:01:47 > 0:01:51What we've learnt from experiments done on these unique,
0:01:51 > 0:01:55unfortunate individuals, has implications for us all.
0:01:56 > 0:01:59It's taught us astonishing things,
0:01:59 > 0:02:03not just how the brain works, but its hidden potential.
0:02:03 > 0:02:07I'm actually using it pretty much like I would use vision.
0:02:09 > 0:02:10Excellent.
0:02:23 > 0:02:29Angela, a 45-year-old mother, has been having epileptic fits.
0:02:29 > 0:02:31- NURSE:- One, two, three.
0:02:31 > 0:02:33Her temporal lobe is damaged,
0:02:33 > 0:02:37creating of electrical impulses that spread across her brain
0:02:37 > 0:02:41causing frequent, uncontrollable seizures.
0:02:42 > 0:02:46Drugs haven't worked, so she's opted for a more radical treatment.
0:02:50 > 0:02:54We're going to take out roughly a line like...
0:02:54 > 0:02:56- A line like that.- Right.
0:02:56 > 0:03:02Her surgeon, Paul Eldridge, is about to remove part of her brain.
0:03:02 > 0:03:07The damage lies deep inside the brain, beneath the temporal lobe.
0:03:07 > 0:03:10Paul has to open her skull and navigate
0:03:10 > 0:03:15through critical regions of her brain to reach the area.
0:03:15 > 0:03:18It is an extremely delicate procedure.
0:03:18 > 0:03:23It should end Angela's fits, but there are significant risks.
0:03:28 > 0:03:32The knowledge to make this operation possible has been hard-won.
0:03:32 > 0:03:36Success relies on a detailed understanding
0:03:36 > 0:03:39of what different parts of the brain do.
0:03:39 > 0:03:42We all know that thoughts, ideas, beliefs,
0:03:42 > 0:03:46the things that make us human, are somehow generated
0:03:46 > 0:03:50within this lump of grey porridge up here in our heads.
0:03:50 > 0:03:54But until relatively recently, that wasn't fully understood.
0:03:54 > 0:03:58In fact, up until about 150 years ago,
0:03:58 > 0:04:02we knew very little about what the human brain actually did.
0:04:03 > 0:04:05MECHANICAL WHIRRING
0:04:07 > 0:04:11So, how did doctors begin to put it all together?
0:04:11 > 0:04:15How did they first start to map the brain?
0:04:29 > 0:04:33I've come to Paris to see a very special brain,
0:04:33 > 0:04:36because it kick-started the whole of modern neuroscience
0:04:36 > 0:04:39and it also utterly transformed our understanding
0:04:39 > 0:04:41of how our own brains work.
0:04:45 > 0:04:49The brain I'm looking for should be in this room here.
0:04:49 > 0:04:51Ha! Wow.
0:04:53 > 0:04:54Wow...
0:05:06 > 0:05:11Anatomists in the 19th century made great strides in understanding
0:05:11 > 0:05:14how the key organs in the body work.
0:05:14 > 0:05:17And through studying deformed and diseased specimens,
0:05:17 > 0:05:20such as these at the Dupuytren Museum,
0:05:20 > 0:05:24they were able to learn how our organs develop.
0:05:24 > 0:05:27But by far the hardest organ to study was the brain.
0:05:27 > 0:05:31Unlike other organs, you cannot guess which bits of the brain do
0:05:31 > 0:05:34what simply by looking at them.
0:05:34 > 0:05:40Then, in 1861, a surgeon was called to the bedside of a dying man.
0:05:41 > 0:05:46His name was Leborgne, and we know relatively little about him.
0:05:46 > 0:05:49Legend has it that as a young man he contracted syphilis,
0:05:49 > 0:05:52rather like this unfortunate over here.
0:05:52 > 0:05:55And as a result of that, he lost the power of speech,
0:05:55 > 0:05:58apart from the ability to say one word, "tan".
0:06:01 > 0:06:04Leborgne had gangrene in his right leg,
0:06:04 > 0:06:07and local surgeon Paul Broca was asked to examine him.
0:06:07 > 0:06:13Broca became intrigued by Leborgne's unusual speech impediment.
0:06:13 > 0:06:18His voice box was undamaged, and he clearly understood questions,
0:06:18 > 0:06:21so why could he only say "tan"?
0:06:25 > 0:06:27Broca could do nothing for Leborgne.
0:06:27 > 0:06:30The gangrene spread, and he died two days later.
0:06:30 > 0:06:34The important thing is, Broca knew he had a unique opportunity
0:06:34 > 0:06:36and he seized it with both hands.
0:06:36 > 0:06:40He got out his saw, he cut open Leborgne's head,
0:06:40 > 0:06:44and he extracted his brain, this brain.
0:06:44 > 0:06:48This is the brain that Broca removed.
0:06:48 > 0:06:53It's in pretty manky condition, but then again, it's 150 years old.
0:06:53 > 0:06:57And it is fairly obvious, when you look at it, where the damage lies,
0:06:57 > 0:07:00it's this region over here.
0:07:00 > 0:07:04Broca was able to put two and two together.
0:07:04 > 0:07:08Leborgne had suffered from a severe problem with his speech -
0:07:08 > 0:07:09he could only say, "tan, tan".
0:07:09 > 0:07:12There's a big chunk of his brain missing here.
0:07:12 > 0:07:16Well, that suggested to Broca that this area here
0:07:16 > 0:07:18must be responsible for speech.
0:07:20 > 0:07:26When news of his discovery got out, Broca became extremely famous.
0:07:26 > 0:07:30He modestly lent his own name to the region he'd uncovered.
0:07:30 > 0:07:32It's known as "Broca's area".
0:07:34 > 0:07:39Whatever caused Leborgne's unfortunate brain damage,
0:07:39 > 0:07:40his life and then death
0:07:40 > 0:07:43helped Paul Broca establish a important principle,
0:07:43 > 0:07:46that different parts of the brain have different skills,
0:07:46 > 0:07:48they do different things.
0:07:48 > 0:07:51It's something called localisation.
0:07:53 > 0:07:57Localisation is at the heart of our understanding
0:07:57 > 0:07:58of how the brain works.
0:07:58 > 0:08:03Today, scientists are still trying to work out, in ever finer detail,
0:08:03 > 0:08:07exactly what different parts of the brain do.
0:08:07 > 0:08:11And it is still patients with damaged brains who offer
0:08:11 > 0:08:13the greatest insights.
0:08:13 > 0:08:17An area that continues to fascinate is the area
0:08:17 > 0:08:20that Paul Broca himself studied - language.
0:08:24 > 0:08:27SHE SPEAKS IN GERMAN
0:08:27 > 0:08:32Julia Sedera is fluent in German, Spanish and English.
0:08:32 > 0:08:35She used to work as a management consultant.
0:08:39 > 0:08:43I used to be on the phone all the time. I used to talk, talk, talk.
0:08:43 > 0:08:48But then, three years ago, she had a massive stroke.
0:08:48 > 0:08:51I could say absolutely nothing.
0:08:51 > 0:08:55When I had to say something, I couldn't even say my...
0:08:55 > 0:08:59Um, my husband's man - name, his name, I couldn't even say his name.
0:08:59 > 0:09:01The only thing I knew was Sophia.
0:09:06 > 0:09:09She seems to have recovered well,
0:09:09 > 0:09:13but when her speech is tested at University College, London,
0:09:13 > 0:09:16a very different picture emerges.
0:09:16 > 0:09:20- You're going to look at the picture. - OK.- And tell me what it is.
0:09:20 > 0:09:26Pi, pi, pe, pa, perry, pa, pike, perry, peak.
0:09:26 > 0:09:28That's it.
0:09:28 > 0:09:32- Pi?- Pi, perry, pay,
0:09:32 > 0:09:35pa, no.
0:09:35 > 0:09:37Can you tell me anything about it?
0:09:37 > 0:09:41It's hot, it's very good, in Brazil loads of people eat that a lot.
0:09:43 > 0:09:47Julia is unable to name things.
0:09:47 > 0:09:53You can buy them, they're called, le, be, ah, bet.
0:09:54 > 0:09:56What do you do with it?
0:09:56 > 0:09:59Put it in there, paper.
0:09:59 > 0:10:01Envel?
0:10:01 > 0:10:04- Again.- Envelope.- Elephone?
0:10:04 > 0:10:06Envelope.
0:10:06 > 0:10:08For neurologist Cathy Price,
0:10:08 > 0:10:11rare cases like Julia are an invaluable opportunity
0:10:11 > 0:10:15to learn more about the intricacies of speech.
0:10:15 > 0:10:18It's very clear when you're speaking to her,
0:10:18 > 0:10:23that she understands what is happening, what she's looking at.
0:10:23 > 0:10:26Rum, brum, brum, tummel.
0:10:26 > 0:10:30She's also able to generate a lot of speech that sounds very fluent.
0:10:30 > 0:10:35The problem that she has is linking up.
0:10:35 > 0:10:39Finding the right words to describe the meanings she's thinking of.
0:10:39 > 0:10:41Jur, juri, du, jury,
0:10:41 > 0:10:45jury, ah, jury.
0:10:45 > 0:10:48- Are you talking about Egypt? - Yes, that one.
0:10:48 > 0:10:53- Tell me how you feel when you're doing this.- I just...
0:10:53 > 0:10:58I've no idea how to say it, I can't even think about it.
0:10:58 > 0:11:01I know exactly what it is, but there is no idea what I can say,
0:11:01 > 0:11:04I don't know what I should say, I just can't say it.
0:11:06 > 0:11:10Unlike Broca, who could only study his patients after they died,
0:11:10 > 0:11:12Cathy can look at Julia's brain
0:11:12 > 0:11:16while it's processing language, to see what's gone wrong.
0:11:16 > 0:11:17"Dome".
0:11:18 > 0:11:20"Cow".
0:11:22 > 0:11:23Looking at Julia's scan,
0:11:23 > 0:11:28the first surprise is her Broca's area is completely intact.
0:11:31 > 0:11:34The damage is further back in her brain.
0:11:36 > 0:11:39This is a picture of the structure of Julia's brain.
0:11:39 > 0:11:43We can see a dark area here, in the parietal cortex,
0:11:43 > 0:11:47where the stroke has caused quite a lot of damage.
0:11:49 > 0:11:52This is one of many areas of the brain
0:11:52 > 0:11:56which are now known to be involved in creating speech.
0:11:56 > 0:12:00The scan also shows Cathy which areas light up
0:12:00 > 0:12:04when Julia tries to speak, which she can compare to a healthy brain.
0:12:04 > 0:12:10The red signal shows that the undamaged Broca's area is active.
0:12:10 > 0:12:15The adjacent blue area is where the damage lies.
0:12:15 > 0:12:17What you can see here in the blue area
0:12:17 > 0:12:20is that she's got less activation than normal.
0:12:20 > 0:12:24And this fits in with her symptoms, in so far as this area here
0:12:24 > 0:12:31is important for, for translating visual information into speech.
0:12:31 > 0:12:33It's because this blue area is damaged
0:12:33 > 0:12:38that Julia can't say "pineapple", even though she knows what it is.
0:12:38 > 0:12:42But there's one other fascinating finding.
0:12:42 > 0:12:45What's interesting is that this yellow area here,
0:12:45 > 0:12:48in the anterior part of the temporal lobe,
0:12:48 > 0:12:51and this is an area of the brain that's associated with meaning,
0:12:51 > 0:12:53this area's more activated,
0:12:53 > 0:12:57which suggests that she's relying more on the meaning of the word
0:12:57 > 0:12:59to work out how to say it.
0:12:59 > 0:13:04Julia is one of hundreds of stroke victims who are contributing
0:13:04 > 0:13:08to Cathy's ambitious project to produce a detailed map
0:13:08 > 0:13:11of brain areas we use for language.
0:13:11 > 0:13:14We now know that there are many, many regions of the brain
0:13:14 > 0:13:15that are involved in language.
0:13:15 > 0:13:20We could probably label half the brain "involved in language".
0:13:20 > 0:13:23And the new research is trying to break those areas down
0:13:23 > 0:13:26into smaller and smaller components,
0:13:26 > 0:13:29where we understand how different areas of the brain
0:13:29 > 0:13:31respond in a much more precise way.
0:13:33 > 0:13:35I think that's very good.
0:13:35 > 0:13:39This picture of language ability spread right across the brain
0:13:39 > 0:13:42helps explain Julia's partial recovery.
0:13:46 > 0:13:50Although she's lost a big chunk of brain, Julia communicates
0:13:50 > 0:13:55by using some of the remaining, undamaged language areas.
0:13:56 > 0:14:00I can't say this and that, but I can say, "Can you help me, please?"
0:14:00 > 0:14:04that way or that way, and it, like playing around what I have to say.
0:14:04 > 0:14:06And I'm so much more myself again,
0:14:06 > 0:14:09And I think, "I can't say all these things, so what?"
0:14:09 > 0:14:15I can help with that. I can do what I think I need.
0:14:21 > 0:14:24Taking off the top bit will give me...
0:14:24 > 0:14:26It's an hour into Angela's operation.
0:14:26 > 0:14:29Paul is carefully cutting his way through an area
0:14:29 > 0:14:32called the anterior temporal lobe.
0:14:32 > 0:14:37He's about a centimetre from the area that's triggering her epilepsy.
0:14:37 > 0:14:42Temporal lobe down here, so that's going to be coming out.
0:14:42 > 0:14:46He's picked his way through Angela's brain
0:14:46 > 0:14:48without doing her serious harm, thanks to maps.
0:14:48 > 0:14:52Maps based on years of painstaking experimentation.
0:14:52 > 0:14:56It means Paul knows which areas are safe to pass through.
0:14:56 > 0:14:59What should that bit of brain be doing?
0:14:59 > 0:15:04Not much, so that if you take it out, not much seems to happen.
0:15:04 > 0:15:07It's hard to believe there are bits of brain that don't do anything.
0:15:07 > 0:15:10- They used to be known as the "silent areas".- Right.
0:15:13 > 0:15:18Now Paul really has an excellent idea of where he is,
0:15:18 > 0:15:20he's got all this technology around him.
0:15:20 > 0:15:22But in the early days of neuroscience,
0:15:22 > 0:15:25they had very imprecise maps
0:15:25 > 0:15:30and as a result, mistakes were made and terrible tragedies occurred.
0:15:30 > 0:15:36But from those tragedies, the greatest lessons were learned.
0:15:44 > 0:15:48Perhaps the most notorious example of a surgical intervention
0:15:48 > 0:15:51that went horribly wrong occurred in 1953.
0:15:54 > 0:15:59For a long time, the patient, Henry Molaison,
0:15:59 > 0:16:04was one of psychology's most closely guarded secrets -
0:16:04 > 0:16:08known only by his initials, HM.
0:16:15 > 0:16:18- TAPE:- Do you know what you did yesterday?- No, I don't.
0:16:18 > 0:16:21How about this morning?
0:16:21 > 0:16:23I don't even remember that.
0:16:27 > 0:16:31Can you tell me what day of the week it is?
0:16:31 > 0:16:33No, I can't.
0:16:37 > 0:16:41An accident when he was young triggered a chain of events
0:16:41 > 0:16:43that robbed Henry of a normal life,
0:16:43 > 0:16:48but helped science unravel one of the great mysteries of the mind,
0:16:48 > 0:16:50how our memories work.
0:16:54 > 0:16:59When he was seven years old, Henry was playing in the street.
0:16:59 > 0:17:03Something caught his eye and he ran out onto the road.
0:17:09 > 0:17:13He was knocked to the ground by a passing bicycle.
0:17:13 > 0:17:17A trivial-sounding accident, the sort that happens all the time.
0:17:20 > 0:17:23Young Henry needed a number of stitches in his head,
0:17:23 > 0:17:25but seemed otherwise OK.
0:17:25 > 0:17:30Yet this trivial incident would shape his entire life,
0:17:30 > 0:17:33and would eventually lead to his becoming the most studied person
0:17:33 > 0:17:36in the whole history of psychology.
0:17:38 > 0:17:43At first, things carried on normally, Henry played with friends,
0:17:43 > 0:17:46went on trips with his father.
0:17:46 > 0:17:50But increasingly, he found himself having vacant periods
0:17:50 > 0:17:52that he couldn't account for.
0:17:56 > 0:18:00On his 16th birthday, Henry got into his parents' car
0:18:00 > 0:18:04and prepared to head off to town to celebrate.
0:18:07 > 0:18:10As they crossed the bridge into Hartford,
0:18:10 > 0:18:16Henry's body seized up, his limbs and head jerking violently.
0:18:16 > 0:18:22The childhood head injury had left a terrible legacy - epilepsy.
0:18:22 > 0:18:26From then on, Henry's life was dominated by his illness.
0:18:26 > 0:18:30In the 1940s, attitudes were less enlightened.
0:18:30 > 0:18:32His father turned his back on him,
0:18:32 > 0:18:37saying it was "shameful to have a mental in the family".
0:18:40 > 0:18:45By age 27, he was having massive seizures on a weekly basis.
0:18:45 > 0:18:47Something had to be done.
0:18:51 > 0:18:55He was referred to a local surgeon, William Scoville,
0:18:55 > 0:19:00whose chief specialities were ruptured discs and lobotomies.
0:19:02 > 0:19:06A colleague of Scoville's described him as a free spirit,
0:19:06 > 0:19:08unfettered by rules or regulations.
0:19:08 > 0:19:12Probably not the sort of man you'd want operating on your son.
0:19:14 > 0:19:18Scoville thought an area of the brain called the hippocampus
0:19:18 > 0:19:20might be causing Henry's epilepsy.
0:19:20 > 0:19:23Little was known about this region,
0:19:23 > 0:19:27and surgeons hadn't dared penetrate that deeply into the brain.
0:19:27 > 0:19:29So, on no more than a hunch,
0:19:29 > 0:19:35Scoville decided to remove Henry's hippocampus and see what happened.
0:19:35 > 0:19:39With Henry anaesthetised, but fully awake,
0:19:39 > 0:19:44Scoville drilled into his skull, then pulled out his favourite tool.
0:19:44 > 0:19:48He inserted a silver straw deep into Henry's brain
0:19:48 > 0:19:51and then started to suck.
0:19:51 > 0:19:55Since Henry was awake throughout, you wonder what he made of it.
0:19:55 > 0:19:58By the time Scoville paused for breath,
0:19:58 > 0:20:02he had sucked out the entire structure known as the hippocampus,
0:20:02 > 0:20:03and some of the cells around it.
0:20:10 > 0:20:15Not surprisingly, Henry emerged from the operation a changed man.
0:20:15 > 0:20:18He still had his personality and his IQ,
0:20:18 > 0:20:22but he could no longer form new memories.
0:20:22 > 0:20:24It was like he was lost in a deep fog.
0:20:24 > 0:20:26He could remember his childhood,
0:20:26 > 0:20:30and up to the operation, but nothing after that.
0:20:34 > 0:20:38- TAPE: Well, I possibly had an operation or something.- Uh-huh?
0:20:38 > 0:20:41- Tell me about that. - I don't remember it.
0:20:41 > 0:20:44Do you remember your doctor's name?
0:20:44 > 0:20:46No, I don't.
0:20:46 > 0:20:50- Does the name Doctor Scoville sound familiar?- Yes, that does.
0:20:50 > 0:20:53Tell me about Doctor Scoville.
0:20:53 > 0:20:57Well, he did medical research on people.
0:20:59 > 0:21:05At first, Doctor Scoville seemed unconcerned by his error.
0:21:05 > 0:21:08Apparently, he went home to his wife and said,
0:21:08 > 0:21:12"Guess what? I tried to cut the epilepsy out of a patient,
0:21:12 > 0:21:16"and instead took his memory. What a trade!"
0:21:17 > 0:21:22He admitted that the surgery had been frankly experimental,
0:21:22 > 0:21:26and urged other surgeons not to repeat his dreadful mistake.
0:21:36 > 0:21:40One thing Scoville did get right was he kept meticulous notes
0:21:40 > 0:21:43of exactly what he had removed.
0:21:43 > 0:21:49His clean surgical strike meant he had created the perfect amnesiac.
0:21:49 > 0:21:53Henry's surgically altered brain was a potential gold mine
0:21:53 > 0:21:56for psychologists keen to understand
0:21:56 > 0:21:59exactly how it is we build memories.
0:21:59 > 0:22:02For the next 50 years, Henry was visited almost daily
0:22:02 > 0:22:07by a stream of eager researchers, keen to try out their ideas.
0:22:08 > 0:22:12One of the last academics to come here to Henry's care home
0:22:12 > 0:22:16and investigate his brain was Professor Elizabeth Kensinger,
0:22:16 > 0:22:20from the Massachusetts Institute of Technology.
0:22:20 > 0:22:23- Good morning. Hello.- Good morning.
0:22:23 > 0:22:25- Hello.- Hi, it's very nice to meet you.
0:22:25 > 0:22:29Do you think he minded at all, people coming in and
0:22:29 > 0:22:33probing around inside his head, or asking him questions all the time?
0:22:33 > 0:22:36I don't think so! Of course, he would have no idea
0:22:36 > 0:22:39that people had come with him to this frequency.
0:22:39 > 0:22:43We would have a natural banter and he would know what was going on.
0:22:43 > 0:22:45But if there was a knock at the door,
0:22:45 > 0:22:47and I had to talk to that person,
0:22:47 > 0:22:51when I looked back at Henry, he no longer had any idea
0:22:51 > 0:22:54of what we'd been talking about before.
0:22:54 > 0:22:57Why was there so much interest in Henry?
0:22:57 > 0:23:01We suddenly understood that there was a particular part of the brain,
0:23:01 > 0:23:04the hippocampus and the tissues surrounding the hippocampus,
0:23:04 > 0:23:08that was important, and that if you didn't have that tissue,
0:23:08 > 0:23:11you weren't going to be able to record new memories
0:23:11 > 0:23:13that you would have conscious access to.
0:23:16 > 0:23:20Now they knew that the hippocampus was crucial for creating memories
0:23:20 > 0:23:22from the events of our lives,
0:23:22 > 0:23:27researchers could begin to explore the details of how it did this.
0:23:29 > 0:23:34Memories require a diffuse association between many areas.
0:23:36 > 0:23:40If you think about your conscious memory of having breakfast,
0:23:40 > 0:23:44it'll the sight of the food, the smell, the taste of the food,
0:23:44 > 0:23:48it's going to involve all of these different elements.
0:23:49 > 0:23:53You need some part of the brain that can bind together elements
0:23:53 > 0:23:56and have it be a representation that comes back to you
0:23:56 > 0:23:58and that feels complete.
0:24:02 > 0:24:09It's astonishing how much research was generated from this one man.
0:24:09 > 0:24:11He generated an awful lot of research, didn't he?
0:24:11 > 0:24:15There have been over 100 scientists that have worked with him,
0:24:15 > 0:24:18and more than 10,000 articles that have cited studies
0:24:18 > 0:24:21that have been done with him.
0:24:21 > 0:24:24Everything that we know about memory
0:24:24 > 0:24:26began with the study of Henry.
0:24:27 > 0:24:31Down the years, every aspect of Henry's mind was examined,
0:24:31 > 0:24:36from the content of his dreams to his memory for pain.
0:24:36 > 0:24:40OK, so if you want to come on in here, this is a...
0:24:40 > 0:24:44But a simple experiment, involving nothing more than a mirror,
0:24:44 > 0:24:48was perhaps the most surprising and revealing of them all.
0:24:48 > 0:24:51So what I'd like for you to do in this task
0:24:51 > 0:24:54is to just look at the reflection in the mirror,
0:24:54 > 0:24:57and use that to try to trace along the outline of the star
0:24:57 > 0:24:59that you see there in the mirror.
0:24:59 > 0:25:01OK, so a very simple task.
0:25:01 > 0:25:05I'm going away, therefore I'm coming toward.
0:25:07 > 0:25:10Damn! The opposite doesn't,
0:25:10 > 0:25:12the opposite takes me off in that direction,
0:25:12 > 0:25:14so I need to do the inverse opposite.
0:25:14 > 0:25:18Now I just think, OK, I just go that way!
0:25:18 > 0:25:21But you don't go that way... No, not that way.
0:25:21 > 0:25:23Cor, blimey, I'm done, I'll take my hand out.
0:25:23 > 0:25:26- All right.- How long did that take?
0:25:26 > 0:25:29- Not very impressive, I don't think. - That's it.
0:25:29 > 0:25:32This is pretty typical of a first trial, actually.
0:25:32 > 0:25:37When Henry was given the mirror test to do, over a series of days,
0:25:37 > 0:25:40he quickly became very good at it,
0:25:40 > 0:25:45despite insisting each time that he had never done the test before.
0:25:45 > 0:25:47This revealed that Henry's surgery
0:25:47 > 0:25:50had removed his ability to form new conscious memories,
0:25:50 > 0:25:53or episodic memories, but it hadn't disrupted his ability
0:25:53 > 0:25:56to show learning on these types of motor tasks.
0:25:56 > 0:26:01Since he had no hippocampus, remembering physical skills
0:26:01 > 0:26:04must be processed in a different part of the brain.
0:26:04 > 0:26:06- And this was big?- This was huge.
0:26:06 > 0:26:09Before this time, we didn't really understand
0:26:09 > 0:26:12that there were different forms of memory.
0:26:12 > 0:26:16Henry had unwittingly contributed to a major discovery,
0:26:16 > 0:26:19that there are two types of memory.
0:26:19 > 0:26:23One allows us to unconsciously remember physical skills,
0:26:23 > 0:26:25like riding a bike.
0:26:25 > 0:26:30The other, to consciously recall the moments of our life.
0:26:30 > 0:26:36Henry died in 2008, at the grand old age of 82.
0:26:36 > 0:26:40Many people came to his funeral, mostly academics.
0:26:40 > 0:26:43He had transformed our understanding of memory,
0:26:43 > 0:26:46but he had no idea of the part he'd played.
0:26:46 > 0:26:50- TAPE:- How long have you had trouble remembering things?
0:26:50 > 0:26:52That I don't know myself.
0:26:52 > 0:26:55I can't tell you, because I don't remember.
0:26:57 > 0:27:00What do you think you'll do tomorrow?
0:27:00 > 0:27:06- Whatever's beneficial.- Good answer.
0:27:12 > 0:27:17The story of Henry's brain didn't end with his death.
0:27:17 > 0:27:20His brain was considered so important to neuroscience,
0:27:20 > 0:27:25it was removed within hours of his death, and taken on a long journey.
0:27:29 > 0:27:32Henry's brain ended up here in San Diego,
0:27:32 > 0:27:35at a specially built facility,
0:27:35 > 0:27:39thousands of miles away from where he had lived and died.
0:27:42 > 0:27:45This multi-million pound brain observatory
0:27:45 > 0:27:50was set up specially so scientists could continue to learn from Henry.
0:27:52 > 0:27:56Henry's became the first brain to undergo an experimental procedure,
0:27:56 > 0:27:59devised by Professor Jacopo Annese.
0:28:01 > 0:28:08It's been shaved forensically into 2,401 micro-thin segments
0:28:08 > 0:28:12and put through a chemical process to preserve every detail.
0:28:14 > 0:28:17"Brain Observatory", I think I'm in the right place.
0:28:20 > 0:28:22- Come in.- Hello, there.
0:28:22 > 0:28:26- Michael Mosley, how do you do? - Jacopo.- What a fantastic office!
0:28:26 > 0:28:28- Thank you. - I've come to see Henry's brain.
0:28:28 > 0:28:31OK. It's the only brain that I keep in my office.
0:28:31 > 0:28:36- OK.- So we're going to show you some slides.
0:28:37 > 0:28:40To Jacopo, these slides are not research,
0:28:40 > 0:28:43they are the essence of Henry.
0:28:43 > 0:28:47- It's not just a specimen, it's a person.- Yes, he had a life.
0:28:47 > 0:28:51Even calling them by name, you know, knowing who they were,
0:28:51 > 0:28:55everybody here just feels very...more reverent.
0:28:55 > 0:29:00- We're continuing the biography of HM, based on these images.- Yes.
0:29:03 > 0:29:06The new technique involves taking very high resolution images
0:29:06 > 0:29:12of each slice of brain, which can then be examined in all dimensions.
0:29:12 > 0:29:15It's brain-mapping on a micro level,
0:29:15 > 0:29:18the most precise ever attempted.
0:29:18 > 0:29:21The goal was to be able to navigate everywhere in the brain,
0:29:21 > 0:29:23to look at single neurons.
0:29:23 > 0:29:26Now, this is the resolution that we need to understand
0:29:26 > 0:29:30- exactly what structures were affected by the lesion.- OK.
0:29:30 > 0:29:33This new data can be cross-referenced
0:29:33 > 0:29:38to the psychological research collected on Henry over the years.
0:29:38 > 0:29:42The aim is to build a complete picture of how the memory works,
0:29:42 > 0:29:46right down to the level of the neuron.
0:29:46 > 0:29:50- This is massively detailed.- This is a massive amount of data too.
0:29:50 > 0:29:54But you see, you can recognise individual cells.
0:29:54 > 0:29:56So we're zooming in now.
0:29:56 > 0:30:01You can resolve individual neurons in the cortex, individual fibres.
0:30:01 > 0:30:06- You can go in the little alleyways, not just the big freeways.- Yes.
0:30:07 > 0:30:10The brain observatory is expanding,
0:30:10 > 0:30:14opening its doors to other extraordinary individuals
0:30:14 > 0:30:18who have been studied in life, and will now be studied in death.
0:30:18 > 0:30:21They have a hugely ambitious goal,
0:30:21 > 0:30:26to find physical traces in the brain of all our memories.
0:30:26 > 0:30:30Do you think ultimately we'll be able to make more sense of this?
0:30:30 > 0:30:35We're trying to find out if there is, indeed, like clues left behind.
0:30:35 > 0:30:36Like of this conversation -
0:30:36 > 0:30:42will there be something in these images in our brains.
0:30:42 > 0:30:44That it's a testimony of what happened.
0:30:44 > 0:30:48- That's what is fascinating to me. - Are we getting closer to that?
0:30:48 > 0:30:52It seems to me that you're getting to ever greater complexity.
0:30:52 > 0:30:55We don't know what's relevant, that's the big question mark.
0:30:55 > 0:30:59That's why we're trying to catalogue and to make a registry
0:30:59 > 0:31:02that will catalogue every little detail in the brain.
0:31:02 > 0:31:06Jacopo is carefully preserving unusual brains,
0:31:06 > 0:31:09in the hope that scholars in the future
0:31:09 > 0:31:14will be able to study them using technologies we cannot yet imagine.
0:31:14 > 0:31:18The Latins used to say, "what's in writing stays".
0:31:18 > 0:31:23So, this is what was written in the brain, and you cannot change that.
0:31:27 > 0:31:31So, a story which begins with a boy being hit by a bicycle
0:31:31 > 0:31:35nearly 80 years ago ends with his brain being preserved
0:31:35 > 0:31:39in this building in the form of thousands of slices,
0:31:39 > 0:31:42but also terabytes of data.
0:31:42 > 0:31:43It is a form of immortality
0:31:43 > 0:31:47that I'm sure Henry himself would never have dreamt of.
0:31:56 > 0:31:58I'll check some...
0:31:58 > 0:32:02It's now 90 minutes into Angela's epilepsy operation,
0:32:02 > 0:32:05and Paul has succeeded in exposing the scarred area
0:32:05 > 0:32:08within her temporal lobe that he wants to remove.
0:32:08 > 0:32:11- This is the source of her epilepsy? - Yeah.
0:32:11 > 0:32:13So when you remove that,
0:32:13 > 0:32:17what's the chance that will cure her epilepsy?
0:32:17 > 0:32:21The stated figures are around...
0:32:21 > 0:32:24a 70% seizure-free rate.
0:32:25 > 0:32:27'Angela is fortunate.
0:32:27 > 0:32:30'Paul has identified the focus of her seizures.
0:32:30 > 0:32:34'When that isn't possible, a more drastic form of surgery,
0:32:34 > 0:32:38'pioneered more than 60 years ago, may be called for.'
0:32:38 > 0:32:44Back in the 1940s, surgeons decided to try a radical new approach.
0:32:44 > 0:32:48Instead of, as with Angela, cutting out a small section of the brain,
0:32:48 > 0:32:52they decided it would be a good idea to cut the corpus callosum,
0:32:52 > 0:32:57the highway that connects the two hemispheres of the brain.
0:32:57 > 0:33:01The effect of doing this was utterly unexpected.
0:33:01 > 0:33:04- TV:- 'Put your left hand through the screen. OK.
0:33:04 > 0:33:07'I'm going to put a number in your hand now.
0:33:07 > 0:33:11'He observes what happens when the housewife cannot see her hands.
0:33:11 > 0:33:13'Can you tell me what that number was?
0:33:13 > 0:33:15'Four?'
0:33:19 > 0:33:24The corpus callosum is a band of 55 million nerve fibres
0:33:24 > 0:33:28which connect the two halves of the brain and keep them in contact.
0:33:30 > 0:33:34OK, Dave, I'm going to start to divide the corpus callosum.
0:33:36 > 0:33:40In the new operation, surgeons slice through this superhighway,
0:33:40 > 0:33:42disconnecting the two halves of the brain.
0:33:42 > 0:33:47This halted the electrical activity that caused seizures.
0:33:47 > 0:33:49After they had recovered from their operation,
0:33:49 > 0:33:51they appeared to be normal.
0:33:53 > 0:33:56Which was amazing, given the extent to which
0:33:56 > 0:34:00the whole architecture of their brains had been altered.
0:34:00 > 0:34:06This 12-year-old boy is doing some pretty impressive subdivision,
0:34:06 > 0:34:08and his spelling isn't bad either.
0:34:12 > 0:34:15But in psychology circles, they became legends.
0:34:15 > 0:34:19And that is because these patients would, in time,
0:34:19 > 0:34:23reveal something that to me is truly astonishing.
0:34:23 > 0:34:28The two halves of our brain contain a sort of separate consciousness.
0:34:28 > 0:34:33Each hemisphere is capable of its own independent action.
0:34:33 > 0:34:37This sensational finding came about by accident.
0:34:37 > 0:34:41A group of scientists in California recognised
0:34:41 > 0:34:45the experimental potential of the split-brain patients.
0:34:45 > 0:34:48As their brains had been separated, it was a unique opportunity
0:34:48 > 0:34:53to find out if the different hemispheres had different abilities,
0:34:53 > 0:34:55and if so, what?
0:34:57 > 0:35:01To do this, they had to devise ingenious experiments
0:35:01 > 0:35:04that would test each hemisphere in isolation.
0:35:04 > 0:35:08Neurobiologist Roger Sperry set to work.
0:35:08 > 0:35:12The results were bizarre, for the patients and for the researchers.
0:35:12 > 0:35:16I remember seeing this footage nearly 30 years ago,
0:35:16 > 0:35:19and being completely blown away.
0:35:19 > 0:35:24Sperry's experiments made use of the fact that the right hand
0:35:24 > 0:35:28is controlled by the left hemisphere, and vice versa.
0:35:28 > 0:35:32- RESEARCHER:- Put your left hand through the screen, OK.
0:35:32 > 0:35:35I'm going to put a number in your hand now.
0:35:35 > 0:35:38And what I want you to do is signal the answer.
0:35:38 > 0:35:40So here's the first number.
0:35:45 > 0:35:47So far, no great surprises.
0:35:47 > 0:35:50But then the researcher asks her to name out loud
0:35:50 > 0:35:53the number that she's got in her hand.
0:35:53 > 0:35:56Can you tell me what that number was?
0:35:56 > 0:35:57Four? >
0:35:57 > 0:36:00OK. Now let me give you another number.
0:36:10 > 0:36:13She gestures eight, which is the correct answer.
0:36:13 > 0:36:17- Can you tell me again what the number was?- Six?
0:36:17 > 0:36:21But she says "six", which is of course completely wrong.
0:36:21 > 0:36:23So what's going on?
0:36:23 > 0:36:27What was happening is the numbers were put in her left hand,
0:36:27 > 0:36:30which is controlled by the right hemisphere.
0:36:30 > 0:36:33The right hemisphere can't speak, so the left hand communicated
0:36:33 > 0:36:38with researchers by waving fingers up like that.
0:36:38 > 0:36:41The left hemisphere meanwhile is completely in the dark.
0:36:41 > 0:36:49It cannot see or feel what the left hand is doing, so it guesses.
0:36:49 > 0:36:51Five.
0:36:51 > 0:36:55This was the first proof of what people had previously suspected,
0:36:55 > 0:37:00that language resides solely in the left hemisphere.
0:37:02 > 0:37:07Sperry now decided to find out just what the right hemisphere could do.
0:37:11 > 0:37:13So what's happening here is the left hand,
0:37:13 > 0:37:18controlled by the right hemisphere, is being given a puzzle to solve.
0:37:18 > 0:37:24The puzzle required rearranging blocks so they matched the picture.
0:37:24 > 0:37:29And it's pretty good, it gets the puzzle solved pretty damn fast.
0:37:32 > 0:37:37So now it's the turn of the other hemisphere,
0:37:37 > 0:37:42and I have to say it's making a real pig's ear of it.
0:37:42 > 0:37:48The left hemisphere hasn't got a clue how to solve this puzzle.
0:37:48 > 0:37:51The other hand decides to come in and help.
0:37:53 > 0:37:57No, never going to get there.
0:37:57 > 0:38:00This is pretty convincing evidence that although the left hemisphere
0:38:00 > 0:38:05may have language, the right hemisphere has spatial skills.
0:38:06 > 0:38:08The discovery that the right side
0:38:08 > 0:38:11is responsible for spatial awareness,
0:38:11 > 0:38:13was followed up by other discoveries,
0:38:13 > 0:38:18such as the fact that the right side can recognise faces.
0:38:18 > 0:38:22But more than that, Sperry was convinced that, as he put it,
0:38:22 > 0:38:26each hemisphere is a conscious system in its own right,
0:38:26 > 0:38:30perceiving, thinking, remembering,
0:38:30 > 0:38:34reasoning, willing and emoting.
0:38:36 > 0:38:41In 1981, Sperry received a Nobel Prize for his work,
0:38:41 > 0:38:44but in a cruel twist of fate, by then he was suffering
0:38:44 > 0:38:47from a degenerative brain disease called Kuru,
0:38:47 > 0:38:52probably picked up in the early days of his research splitting brains.
0:39:01 > 0:39:03The split-brain experiments
0:39:03 > 0:39:06had revealed the characteristics of each hemisphere.
0:39:06 > 0:39:12The next question was, how did the two halves interact with each other?
0:39:12 > 0:39:17Most people who have had their corpus callosum cut,
0:39:17 > 0:39:20who've had the split-brain operation, are normal afterwards.
0:39:20 > 0:39:24Cross them in the street and you wouldn't know anything had happened.
0:39:24 > 0:39:29But in some cases, the end results are particularly dramatic.
0:39:31 > 0:39:37From childhood, Karen Byrne suffered from daily epileptic seizures.
0:39:37 > 0:39:41She decided that having her brain surgically split
0:39:41 > 0:39:44was her best chance of a normal life.
0:39:44 > 0:39:46Hello, Karen?
0:39:46 > 0:39:51- Hi, how are you? Nice to meet you. - How do you do? Nice to meet you.
0:39:51 > 0:39:54I did have a little trepidation,
0:39:54 > 0:40:00as to what kind of condition I was going to be in after the surgery.
0:40:00 > 0:40:03I woke up and I'm telling you,
0:40:03 > 0:40:09I was not the same girl I was 48 hours before that day,
0:40:09 > 0:40:11that's for sure.
0:40:11 > 0:40:14I was not the same person.
0:40:14 > 0:40:17And I never would be again.
0:40:19 > 0:40:25Surgery resolved the epilepsy, but created a new problem.
0:40:25 > 0:40:28Dr O'Connor said, "Karen, what are you doing?"
0:40:28 > 0:40:32I just looked at him and I said, "What are you talking about?"
0:40:32 > 0:40:34He said, "Your hand's undressing you."
0:40:34 > 0:40:38- And I had no idea, my hand was opening up the buttons.- Right.
0:40:38 > 0:40:42And so I'm rebuttoning them with the right hand,
0:40:42 > 0:40:44and the left hand's unbuttoning them.
0:40:44 > 0:40:47And he put in an emergency call through to Dr Sprung,
0:40:47 > 0:40:50said, "Mike, you've got to get here right away.
0:40:50 > 0:40:53"You've got to get here, we've got a problem."
0:40:53 > 0:40:56- DOCTOR:- Can you lift your hands up in the air?
0:40:56 > 0:40:59How about the other hand, can you lift your left hand in the air?
0:40:59 > 0:41:01Karen emerged from the operation
0:41:01 > 0:41:04with a left hand that had a mind of its own.
0:41:04 > 0:41:08An extremely rare condition known as alien hand syndrome.
0:41:08 > 0:41:09You look almost possessed there.
0:41:09 > 0:41:15Yep, that's how you do look, yes. It's terrible, it's terrible.
0:41:15 > 0:41:18She was eventually discharged from hospital,
0:41:18 > 0:41:22but she had to live with a wayward, wilful hand.
0:41:22 > 0:41:25This hand would do one thing, and this hand would do the opposite.
0:41:25 > 0:41:27So you're trying to have a cigarette...
0:41:27 > 0:41:29Yes, this hand would put it out.
0:41:29 > 0:41:32The phone would ring and I would answer it,
0:41:32 > 0:41:36and the left hand would hit the clicker.
0:41:36 > 0:41:39The thing on the phone, to hang up the phone.
0:41:39 > 0:41:42It is just like an annoying five-year-old, isn't it?
0:41:42 > 0:41:48Definitely. Definitely, and it got so frustrating.
0:41:48 > 0:41:53And then you couldn't get mad at it, because it was you.
0:41:54 > 0:41:57Karen's alien hand syndrome was caused
0:41:57 > 0:42:01by a power struggle going on in her brain.
0:42:01 > 0:42:03Our brains normally function smoothly,
0:42:03 > 0:42:06because the analytical left hemisphere dominates,
0:42:06 > 0:42:09having the final say in what actions we perform.
0:42:09 > 0:42:14And this was certainly true of the bulk of the split-brain patients.
0:42:14 > 0:42:18Karen was extremely unlucky. After the operation,
0:42:18 > 0:42:21the right side of her brain refused to be dominated by the left,
0:42:21 > 0:42:25leaving her hands in near constant conflict.
0:42:25 > 0:42:29It's very strange, isn't it, the thought that all of us, within us,
0:42:29 > 0:42:31have these two hemispheres,
0:42:31 > 0:42:35and that they are wrestling, to some extent, for dominance.
0:42:35 > 0:42:38- Yes, yes, yes.- And that normally the left is in control,
0:42:38 > 0:42:41but in your case, after the split-brain,
0:42:41 > 0:42:43the right became very powerful.
0:42:43 > 0:42:47Oh, defintely. It's so dominant! Oh, my gosh!
0:42:47 > 0:42:52And, for a short period of time, it frightened me, it really did,
0:42:52 > 0:42:58because I just didn't understand why it was fighting so hard
0:42:58 > 0:43:01to have such power over the other side.
0:43:01 > 0:43:05'Finally, her doctors found a medication that restrained
0:43:05 > 0:43:08'her impulsive right hemisphere,
0:43:08 > 0:43:13'bringing her alien hand back under her conscious control.'
0:43:13 > 0:43:16If you really think about it, a lot of it is just horrific,
0:43:16 > 0:43:19and yet, you know, it's also tremendously funny.
0:43:19 > 0:43:22Yes, it really is. You've got to admit it!
0:43:22 > 0:43:24How could you not think it's funny?
0:43:24 > 0:43:29Psychiatrists are not encouraged to laugh at their patients, are they?
0:43:29 > 0:43:33BOTH LAUGH
0:43:33 > 0:43:36Karen, thank you, it's been an absolute pleasure.
0:43:36 > 0:43:40- I appreciate everything, thank you. - Lovely to see you.- Thank you.
0:43:40 > 0:43:43- Maybe I should shake both hands. - Yes, I think you should!
0:43:43 > 0:43:46Now see, that's the way to do it. That's the way to do it.
0:43:46 > 0:43:49- Thank you, thank you.- Thank you.
0:43:54 > 0:43:58Life with two warring hemispheres would be impossible.
0:43:58 > 0:44:03Scientists now believe it was the evolution of a left hemisphere
0:44:03 > 0:44:07that was dominant with its human attributes of logic and language
0:44:07 > 0:44:10that helped us become what we are today.
0:44:20 > 0:44:23'It's now a couple of hours into Angela's surgery.
0:44:25 > 0:44:29'Paul is about to remove the scarred area of her temporal lobe
0:44:29 > 0:44:31'that has been triggering her seizures.'
0:44:34 > 0:44:35This is the temporal lobe,
0:44:35 > 0:44:38so this is giving us access to it.
0:44:38 > 0:44:40- There it is.- That is quite a big chunk of brain, isn't it?
0:44:45 > 0:44:47Paul's now removed the damaged area,
0:44:47 > 0:44:52and he's hopeful that she'll now make a full recovery.
0:44:57 > 0:45:01The success of an operation like this, the fact that a surgeon
0:45:01 > 0:45:05can take out a big chunk of brain without damaging the patient,
0:45:05 > 0:45:08is dramatic proof of just how far we have come
0:45:08 > 0:45:12in understanding the anatomy of the brain.
0:45:12 > 0:45:16Angela, open your eyes for me? >
0:45:16 > 0:45:21Hopefully, Angela will now be given a new lease of life.
0:45:32 > 0:45:34There was a final discovery
0:45:34 > 0:45:37that sprang from the study of damaged brains.
0:45:37 > 0:45:40It turns out that the map of brain function
0:45:40 > 0:45:43is not as rigid as scientists had always believed,
0:45:43 > 0:45:48and that has some astonishing implications.
0:45:48 > 0:45:52This new way of thinking was triggered by a personal tragedy,
0:45:52 > 0:45:58one that changed our understanding of what the brain is capable of.
0:45:58 > 0:46:02In 1960, a poet called Pedro Bach-y-Rita
0:46:02 > 0:46:06had a massive paralysing stroke.
0:46:06 > 0:46:11At the time, it was widely believed that once brain tissue is dead,
0:46:11 > 0:46:14there is no real scope for recovery.
0:46:14 > 0:46:18The family were told there was nothing more that could be done.
0:46:18 > 0:46:23Pedro's eldest son George decided to ignore the doctor's advice.
0:46:23 > 0:46:27He took his father home and began a series of exercises
0:46:27 > 0:46:30to see how far he could push his recovery.
0:46:30 > 0:46:34Pedro couldn't talk or walk, so George made him crawl.
0:46:34 > 0:46:38The neighbours were horrified with the idea that the son
0:46:38 > 0:46:41was making this elderly man crawl like a dog.
0:46:41 > 0:46:42But, he started to recover,
0:46:42 > 0:46:45and then George made him do tasks all around the house,
0:46:45 > 0:46:48like washing up, and when he broke the plates,
0:46:48 > 0:46:50he simply replaced them with metal ones.
0:46:50 > 0:46:52He kept at it for three long years,
0:46:52 > 0:46:56by the end of which Pedro had made an almost miraculous recovery.
0:46:58 > 0:47:01He went back to work, got remarried and when he eventually died,
0:47:01 > 0:47:05it was not from a stroke but from a heart attack,
0:47:05 > 0:47:07following a climb up a mountain.
0:47:09 > 0:47:14By that time, Pedro's younger son Paul was a neurologist.
0:47:14 > 0:47:17Because his father had made such a good recovery, he assumed
0:47:17 > 0:47:22the stroke must have affected a small area of his brain.
0:47:22 > 0:47:26Paul took the unusual decision to go to his father's autopsy.
0:47:26 > 0:47:29What he saw was a complete surprise.
0:47:29 > 0:47:31Paul was absolutely stunned.
0:47:31 > 0:47:34There were huge areas of damage in his father's brain.
0:47:34 > 0:47:3897% of the nerves connecting the cortex to the spinal cord
0:47:38 > 0:47:44had been destroyed. So how had Pedro learned to walk again?
0:47:44 > 0:47:47Paul decided that his father's brain
0:47:47 > 0:47:50must have learnt to reorganise itself,
0:47:50 > 0:47:55replacing the dead tissue with other sections of living brain.
0:47:58 > 0:48:02Pedro's example showed that with the right support,
0:48:02 > 0:48:06stroke victims can sometimes make amazing recoveries.
0:48:07 > 0:48:11It helped transform how stroke victims are treated.
0:48:14 > 0:48:16Paul decided to dedicate his life
0:48:16 > 0:48:20to trying to understand what had happened to his father's brain.
0:48:20 > 0:48:24It's a concept we now call neuroplasticity.
0:48:24 > 0:48:28The idea is that your brain can, given the right stimulation,
0:48:28 > 0:48:31reconfigure itself, even in late adulthood.
0:48:39 > 0:48:43Paul wondered just how far this concept could be pushed.
0:48:43 > 0:48:46Just how flexible is the adult brain?
0:48:46 > 0:48:50Can it be trained to work in completely new ways?
0:48:52 > 0:48:57Many of his fellow neurologists did not believe this was possible.
0:48:59 > 0:49:02Paul decided that the best way to convince his sceptical colleagues
0:49:02 > 0:49:06was to build a machine that was able to demonstrate
0:49:06 > 0:49:08just what he was talking about.
0:49:10 > 0:49:13Paul was convinced that the blind can be taught
0:49:13 > 0:49:18to harness the part of the brain that is normally devoted to vision.
0:49:18 > 0:49:21They can literally learn to see,
0:49:21 > 0:49:25using a completely different sense, touch.
0:49:25 > 0:49:29The important point here is that the brain is able to use information
0:49:29 > 0:49:33coming from the skin as if it were coming from the eyes.
0:49:35 > 0:49:40He designed a chair containing a series of vibrating pins
0:49:40 > 0:49:43that made contact with the backs of his blind subjects.
0:49:51 > 0:49:59An image picked up by a camera was then translated into a crude outline by the vibrating pins.
0:50:03 > 0:50:05OK, it's a telephone,
0:50:07 > 0:50:09and the receiver is to the right.
0:50:12 > 0:50:14Bach-y-Rita was something of a maverick.
0:50:14 > 0:50:17His supervisor, a Nobel Prize winner,
0:50:17 > 0:50:20told him to stop playing around with toys.
0:50:20 > 0:50:24But Bach-y-Rita was convinced that his research would demonstrate
0:50:24 > 0:50:28that the brain is far more flexible and far more plastic
0:50:28 > 0:50:30than people gave it credit for.
0:50:33 > 0:50:38So he ignored the well-meant advice and carried on his research,
0:50:38 > 0:50:40here at the University of Wisconsin.
0:50:40 > 0:50:42He died four years ago,
0:50:42 > 0:50:47just as the prototype of an even more ambitious device was completed.
0:50:47 > 0:50:51- This is the thing, is it? - Yes, it is.
0:50:51 > 0:50:53That's a Stephen Hawking box.
0:50:53 > 0:50:55'It's called the brain port,
0:50:55 > 0:51:01'and the idea is it will help the blind see using their tongues.
0:51:01 > 0:51:06'I'm having a go under the instruction of Paul's protege, Aimee Arnoldussen.'
0:51:06 > 0:51:08Looking very stylish.
0:51:08 > 0:51:11'The lenses are blackened so I can't see anything,
0:51:11 > 0:51:14'and there's a camera that translates images to a device
0:51:14 > 0:51:15'that goes in my mouth.'
0:51:15 > 0:51:18- This is going to go on my tongue? - You are correct.
0:51:18 > 0:51:20There are 400 electrodes,
0:51:20 > 0:51:23so each of those electrodes will act like a pixel.
0:51:23 > 0:51:26If you were to increase the intensity, as you do,
0:51:26 > 0:51:29you see the pixilation on the tongue.
0:51:29 > 0:51:32And so any pixel that's white is a strong stimulation,
0:51:32 > 0:51:35any pixel that's black is no stimulation,
0:51:35 > 0:51:36and then with training,
0:51:36 > 0:51:39people feel the grey as medium stimulation.
0:51:41 > 0:51:44I'm going to put something in front of you, to set the intensity.
0:51:47 > 0:51:52You can turn the intensity down, or take it out of your mouth.
0:51:52 > 0:51:56Ooh, that's very, very tickly.
0:51:56 > 0:52:01- I am intensely ticklish, I should have warned you.- I didn't know! OK.
0:52:04 > 0:52:09It looks bizarre, but I'm told you can learn how to use it very fast.
0:52:09 > 0:52:12It's going to go to the front of the tongue.
0:52:12 > 0:52:15This is what a horizontal line feels like, OK.
0:52:15 > 0:52:18It's in the field of view of the camera.
0:52:20 > 0:52:23You're no longer laughing. Are you becoming accustomed to it?
0:52:23 > 0:52:26- Now you know what to expect?- Hmm.
0:52:27 > 0:52:33Whatever I'm looking at now, I feel a stimulation on the left hand side,
0:52:33 > 0:52:37and it's sort of going like that. Don't what I'm looking at, but...
0:52:37 > 0:52:40The contrast that you felt at a diagonal
0:52:40 > 0:52:44is where my shirt and my skin intersect.
0:52:44 > 0:52:46So, I'm just looking at your cleavage!
0:52:46 > 0:52:50I know! I was trying to say that a little bit more delicately!
0:52:50 > 0:52:53- Right, OK. - HE LAUGHS
0:52:53 > 0:52:55Oh, dear, yes...
0:52:57 > 0:53:01'Once I immersed myself in the task and really focused,
0:53:01 > 0:53:05'I was surprised by how quickly I made progress.'
0:53:05 > 0:53:08On that side it's rounded, yes, very good.
0:53:08 > 0:53:11What kind of things have that kind of shape?
0:53:11 > 0:53:14- A spoon.- Very good. Why don't you touch it?
0:53:14 > 0:53:17It's long and thin, and more circular at the end.
0:53:22 > 0:53:24Excellent, that was impressive,
0:53:24 > 0:53:28I wasn't sure you'd even get the key features, but you did.
0:53:28 > 0:53:32What's happening is, it's like a torch which I'm using
0:53:32 > 0:53:35to illuminate an object, you know, and feel round an object,
0:53:35 > 0:53:37and then I get a general sense of its shape.
0:53:37 > 0:53:43I'm using it like I would use vision, I suppose in a funny way.
0:53:43 > 0:53:45Yes, that's exactly what I'm doing.
0:53:46 > 0:53:50'Scanning studies have confirmed that the sensations on the tongue
0:53:50 > 0:53:54'are indeed passing through to the visual cortex,
0:53:54 > 0:53:57'something that wasn't previously thought possible.'
0:53:57 > 0:54:01You're getting good at reaching for and grabbing the objects.
0:54:01 > 0:54:03- Very good. Oh! - HE GIGGLES
0:54:05 > 0:54:07Proof of brain plasticity,
0:54:07 > 0:54:13that the brain, even in adulthood, can reconfigure itself,
0:54:13 > 0:54:17is turning the idea that its structure is unchanging on its head.
0:54:18 > 0:54:22There is a map, but it isn't necessarily fixed.
0:54:24 > 0:54:28The original thought of the brain not being plastic,
0:54:28 > 0:54:30or being very fixed is an old notion.
0:54:30 > 0:54:34Now that you also think that maybe the brain has capabilities
0:54:34 > 0:54:36that we haven't been able to measure yet.
0:54:36 > 0:54:38It responds to its environment.
0:54:38 > 0:54:42It changes as a result of the experiences it gets.
0:54:42 > 0:54:45- Which is rather encouraging. - It sure is, it sure is.
0:54:51 > 0:54:55In the last few decades, we have learned so much that is novel
0:54:55 > 0:54:59and surprising about the workings of our own brains.
0:55:03 > 0:55:05And that, in no small part,
0:55:05 > 0:55:09is thanks to those individuals with damaged brains,
0:55:09 > 0:55:13who played such a crucial role in the history of psychology.
0:55:13 > 0:55:17They were operated and experimented on in the name of science,
0:55:17 > 0:55:21and often with little personal gain.
0:55:23 > 0:55:28Unusual individuals will continue to be prised and probed
0:55:28 > 0:55:33but I do hope that in the future they will also benefit
0:55:33 > 0:55:35from the insights they help uncover.
0:55:37 > 0:55:38We owe them so much,
0:55:38 > 0:55:42because it is from them that we have gleaned the knowledge
0:55:42 > 0:55:44of how our own minds work.
0:55:44 > 0:55:48They've opened a window into who we really are.