Brain Story (2000) s01e04 Episode Script

Human beings are the most advanced animal on the planet.
We've invented machines which allow us to leave the earth.
We've designed instruments to study the furthest reaches of the universe.
How did our brains come to have this extraordinary capacity for perpetual innovation? Although we share nearly 99% of our genes with chimpanzees, there is a gulf separating us from the animal most closely related to us.
There's a fundamental difference between humans and chimpanzees.
However clever they may appear, it seems to me that their agenda is still relatively basic - their main concerns are eating, mating and avoiding danger.
But we are different.
Unlike any other animal on the planet there's something special about our brains that gives us a unique ability to look way beyond mere survival.
Chimpanzees may be highly intelligent and they may have complex social lives, but even the rudiments of human civilisation seem to be missing.
Chimpanzees are capable of fine hand movements but they have no interest in making art or clothing They show no ability to invent new technologies, and constantly improve them, the way we do.
So what is the special feature exclusive to our human brains that has lifted us out of the jungle and placed us this side of the glass? The average human brain is roughly three times as big as a chimpanzees.
They look very similar but how different is the inner circuitry? As our mass of cortex expanded what changes might have taken place inside which could transform our lives so completely? One mental skill which seems to lie at the heart of human behaviour is the ability to work towards a goal, to devise a plan of action, to juggle possibilities, to keep track of changing circumstances as we keep the end goal in mind.
These are essential ingredients of modern life.
We're always working to a mental plan.
How might our brains achieve all this? Clues come from looking at people who have lost this fundamental ability.
When I went to Vietnam I got into a recon unit, and I was there two weeks when they promoted me to sergeant I followed the rules, I was not a garrison soldier as the word goes.
I was what they called a blood soldier.
We were on patrol and ran into a bloody nosed ambush and a grenade came in, the man in front of me and the man behind me were both killed.
I just came out with a few holes in me.
X rays revealed that shrapnel from the grenade had penetrated the front of Michael's brain.
Michael has undergone a rather dramatic transformation.
Before his injury he was a bright, and very promising and assertive soldier.
And subsequent to his injury Michael became unemployable, made many mistakes in social behaviours and relations and has to live a much more limited life now.
Demoted and eventually discharged from the army, Michael has been unable to hold down a steady job.
He's now working under supervision as a hospital janitor.
He's a troubled young man, he doesn't know himself what he's doing or where he's going.
He has no rhyme or reason for what he wants to do.
Whereas before he did have A lot of times when you see him or he comes to visit, it's, he's lost he's aimless.
And you ask him, what would you do and what would you like to do, and well it depends on his mood that day, he either shrugs his shoulders and "l don't know", or "I'd like to get a real nice car," which has nothing to do with anything.
I'm going to start out by giving you ten chips.
Each chip is worth five cents.
Dr Jordan Grafman is trying to establish why Michael's life has fallen apart.
What aspects of his mental abilities have suffered because of the damage to his frontal lobe? This gambling task is designed to testhis ability to weigh up the likely consequences of his actions.
The point of the test, is to see at what stage in the game he decides to stop.
Do you want to stop or do you want to continue? Continue.
High cards, Mike wins a chip.
Ten or less and he loses one.
The cards are deliberately arranged to give him a good winning streak.
Followed by a steady run of losses Normally, people stop while they're ahead.
Continue.
should have kept it! Continue That's it, we're at the end.
You gave me back all your chips.
Why didn't you stop earlier? I would have stopped on the third low card normally if it was my own money, since it was your chips I was playing with You felt, take a chance.
I'd risk it all.
Despite coming up with what seemed like a rational explanation for his poor performance on this test we know that in real life Michael has a tendency to give away money, so in fact it doesn't hold up under the strains and responsibilities of his own daily life.
Michael's personal life has also suffered as a result of his brain damage.
He seems unable to sustain relationships.
He now lives alone, after a series of impulsive marriages.
The first girl I got married to was when I was in the army.
My daughter was raised by my parents, because when the wife and I got divorced my mother thought it would be better if she raised her than me because she didn't think I was fit to raise her.
The second girl that I married, she was a runaway and the reason she ran away from home was because her step mother slapped her.
And I don't even remember asking her to get married.
And the third girl, she was a prostitute.
So she was in a hurry to get married, I don't know why.
The damage to Michael's frontal lobe has destroyed his ability to work towards a long term goal, or to think through the consequences of his actions.
If the situation is well structured and he's given instructions as to what to do, Michael can perform quite well particularly if the instructions are laid out in a step wise manner.
However as the situation becomes less structured and Michael's forced to rely on his own internal thinking to develop and then execute activities and plans, that's where he begins to have trouble, that's where his distractibility begins to show and his difficulty in following ideas and his social problems.
Michael's brain damage also seems to prevent him recognising how much his life has been affected.
I believe it did change me, from what everybody else has told me.
Being on one side of the fence I don't see it, but they see me changed So I kind of figure well yeah it changed me, cos I know some things I did I wouldn't have done.
Cases like Michael's strongly suggest that the frontal lobe plays a vital part in allowing us to develop mental action plans for the future, and then to follow them through.
Without this ability, however intelligent Michael may be the opportunities open to him are severely limited OK there, I'm going to move you back into the scanner.
At Cambridge University, researchers have developed a series of tests to pinpoint more precisely what special mental skills might arise from our frontal lobes.
Unlike many other areas in the brain that have been pretty well mapped now, we really know very little about the frontal lobe, it remains something of an enigma.
So for example things like seeing, hearing, our ability to move we understand which parts of the brain enable us to do those things, but the frontal lobe we still know very little about what it actually does.
I volunteered to take part in an experiment designed to probe how we think things through in our heads.
The aim is to reorganise the balls at the bottom to match the top pattern.
You can't move a ball if there's another one covering it.
Well done, are you happy with that? I am yes.
We'll start the first scan then.
As soon as you see the first problem just start creating solutions.
The task is designed to make me plan the whole sequence of moves in my head, before I start.
Then I have to hold that sequence of moves in mind, as I work through the solution.
A second scan, when I don't have to plan the moves, I just follow instructions, helps filter out any brain activity not directly involved in planning.
We're homing in on which areas of the brain are involved in the higher aspects of planning, over and above the areas that are involved in moving and vision, and all the other components of a normal planning task.
The scans reveal increased activity in a surprisingly small area, so it seems there are specialised regions in the frontal lobe.
Precisely what they're doing, at the nuts and bolts level, we can't yet say.
Fundamentally it seems that our frontal lobe allows us to keep an overall goal in mind, while we simultaneously deal with the here and now.
But how different is that from what chimps can manage? For thirty years, scientists at Georgia University outside Atlanta have been studying the mental skills of chimpanzees.
Recently they've been trying to find the limits of their abilities to plan ahead.
OK I'm going to set up the computer right here.
The beauty of the maze task is that it allows us to get a quantitative estimate of the chimpanzee's ability to look ahead in time.
We in our egocentrism have wanted to view that as being a uniquely human characteristic, but indeed there's no reason to believe that the chimpanzee wouldn't have this capability after all they have to forage for food, they have to deal with defence of themselves and their own kind, they have a lot of yearly planning to do.
So just how good are chimpanzees at planning? One of our chimpanzees, Pansy, is essentially a genius at this.
Not only is she excellent in running very complex multiple choice mazes that she's never seen before, but she can do it better than humans in many instances.
This is a remarkable finding.
Not only does Pansy take very few wrong turns, but she can sometimes see the solution to the maze faster than a human.
To be able to look ahead and find that clear way between where she starts and where she ends reflects a very active pre frontal lobe system.
She's a genius.
So the ability to imagine possible solutions, to plan before acting is not a uniquely human skill.
Chimpanzees do plan ahead.
I don't believe that they can plan ahead nearly so far as we can.
I think also that they reflect upon the past, but not to the degree that we do.
I would suggest that chimpanzees are able to plan ahead over the course of several days, whereas we can plan ahead for years or centuries if we wish.
Our modern city life might appear very different to that of any other animals, but it seems in one respect it is very similar.
Our ability to mull over endless possibilities, to deal with distractions and still keep multiple goals in mind, appears mostly to have grown out of a simple expansion in brain size But what about the one human ability which for centuries was seen as an absolute divide between us and other animals - language? It's language that has triggered the awesome complexity of modern civilisation.
By giving us the means of transmitting knowledge to our children, Ianguage short circuits the need for each generation to start from scratch.
In just a few short years of life each human being will possess thousands of years, of experience.
The rapid development of human culture since the Stone Age would have been impossible without a sophisticated language.
So is there some special physical structure lacking in chimpanzee's brains which accounts for our unique linguistic skills? Somewhere in each of our brains the sounds and meanings of thousands of words are stored.
Somewhere there are also mechanisms for stringing words together, to express what we want to say.
A hundred years ago scientists believed that language depended on two key areas in the left hemisphere.
A region behind the ear identified by a German doctor, Carl Wernicke seemed to be responsible for overall meaning.
It handled word selection and sentence construction.
An area further forward, found by a French doctor Paul Brocka was thought to control the last stage of generating the speech sounds.
Since then a far more complex picture has emerged.
"Ladies and gentlemen, I'm pleased to participate in this evening's discussion of health considerations in the development of energy sources "These considerations have been with us for some time" Dr Wilson Talley award winning nuclear physicist, scientific adviser to the American government will never be able to speak like this again, because he suffered a stroke.
Much very nice, it's March 1998, stroke March the 6th sleep here about 2 pm got up, the bathroom was here, I went shum and fell down.
This arm very strange.
Wilson has since tried to write an account of what happened in his hotel room, the night he had his stroke.
But the brain damage has affected his ability to express himself, and even to read what he has written.
One two and toilet right here, and we have right all the way and crawled, not sure six minutes, I'm not sure.
Where were you? Oh sorry, no New York City.
Wilson took a taxi to catch a flight home to San Francisco Only after circling Manhattan did he finally manage to say the name of the airport.
He touched down in San Francisco 1 2 hours after his stroke and was taken to hospital.
You just got your licence again? Yeah And you've been driving here every day.
A year on he's now able to speak and can even drive himself to the hospital, but his language skills have been badly damaged.
Dr Talley has a great deal of difficulty understanding anything that is said to him or even things that he reads.
And he also has a great deal of difficulty in producing language.
Now what happens when he tries to talk is that the words come out very fluently, but what he says doesn't have a lot of content to it.
He has difficulty in finding the words that he wants, and he has a great deal of difficulty also in producing sentences that are coherent, that really reflect what it is he wants to say.
A brain scan revealed that a haemorrhage had destroyed Iarge parts of Wilson's left hemisphere including the whole of Wernicke's area.
But the more stroke patients like Wilson are studied, the more it seems that Wernicke's area cannot be where all comprehension and sentence construction takes place in the brain.
The pattern of brain damage in every stroke patient is different, and measuring precisely how badly someone's linguistic abilities have been affected is also difficult.
Aspirin.
Wilson is constantly trying to use non verbal cues to make sense of things In a conversational setting Dr Talley relies very heavily on lots of other kinds of information.
Forget it, you can do it, I can't do it.
He relies on facial expressions, on people's gestures on the way they use the intonation in their voice, and he picks up on all this information to help him understand the situation.
So he gives the impression of understanding almost everything.
Now when we put him in a more controlled testing situation where we remove all of those kinds of cues we find in fact he has unfortunately a very profound language disorder.
Now I'm going to show you a picture, and I'd like you to tell me what's going on in that picture.
OK, people right here er from here and.
the people right here have come in here very bad and windows right here.
Wilson seems to understand what's going on here, but he's lost the ability to find the right words and then to put them into sentences.
So who do you think broke the window? This one here and that one there Nina Dronkers has assembled a unique collection of brain scans of stroke patients with language disorders.
It turns out that many have indeed damaged the two classic language areas, but the broader picture reveals a network of many different brain areas which handle specific aspects of language.
We've seen that there are certain patients who have a great deal of trouble really just naming things.
We've found patients who have difficulty understanding the grammatical rules of language.
All of those different kinds of patterns tell us first of all that the process of language is incredibly complex, and also that there must be many different brain areas that sub serve each and every one of those different functions.
"Touch the right circle" Patients often seem to recover some of the basic aspects of language.
Like the ability to recognise word sounds, which suggests that these functions don't require their own specialised brain structures.
"Touch the green square" Green square.
Unfortunately we rarely see complete total recovery in our aphasic patients And the fact is that in most of them, a fairly significant amount of brain has been affected by their injuries, and that it is difficult for other brain areas that have for such a long period of time been doing something else to suddenly take on this new function.
And what we think happens is that the remaining brain areas try to take on this task of language, but they do it in their own way.
And unfortunately they're not as good at it as those left hemisphere language mechanisms, because they haven't been doing that all those years.
I'm better, much better but I'm not the same, not here.
But maybe we can do it, maybe.
We're keeping our fingers crossed, and if anybody can do it you can do it.
This one, it's good.
Further evidence that language arises from a network of sites in the brain, comes from the work of Professor George Ojemann.
Here at Washington University in Seattle he has pioneered an impressively direct way to study language in the brain.
His research began as part of a last ditch effort to treat severe epilepsy through surgery.
The challenge is to remove enough of the epileptic brain tissue, without destroying key functions like speech To plan exactly what tissue I want to take out there are two pieces of information I want to have.
One is that I want to know where the local epileptic activity is in the brain, and I get that by recording the brain wave activities directly from the cortical surface.
The other is that I want to know where the functionally important things are so I can stay out of them.
Hi, you're in the operating room, can you wake up a bit so we can talk to you, Dr Ojemann's doing his work In order to test for language, George Ojemann needs his patients fully awake.
It's a fantastic opportunity to probe the workings of the living brain Ojemann stimulates the brain with a tiny electric current The patient feels no pain, since there are no pain sensors in the brain He maps out the exposed surface with paper numbers, then he stimulates each area in turn.
Please don't move your arm I'd like you to count for me now, I'd like you to start at 1 and just keep counting until I tell you to stop.
Start please 1, 2, 3, 4, Ojemann has shown that even a basic language function Iike counting relies on a wide spread network of sites.
If he hits one of these essential speech areas, then the electric current will stop the patient in her tracks.
14, 1 5, 1 6, 1 6, 17, 1 8 He's also found that everyone's network is laid out differently.
Ok, you can stop! In any individual subject the sites involved in language are very focal, very localised ones about the size of the end of my thumb nail.
But if you look across the population and you say how are these distributed there's a lot of variance, they're in somewhat different locations in most people.
The team here have mapped over 200 people, and they've never found exactly the same mosaic of language sites twice.
These are just the essential ones, they probably represent key intersections in an even wider network of areas involved in language.
We're going to go to electrode number one.
This is a barn.
When George Ojemann asks his patients to respond to a slide show, then we can really see the awesome sophistication of the brain's language system.
Chicken Piano.
This one is This remarkable technique reveals separate networks for many different aspects of language What we find is that the cortex is organised in these separate areas for different language functions, so for example in a multilingual patient you'll find one area that's involved in naming in one language, and another that's involved in naming the same items in another language, at least partly separate.
This is a lion The brain mapping has even shown that there are separate areas for different categories of word We seem to have a network dedicated to naming fruits, and another for naming tools.
This is a saw.
This is an Screwdriver In a general sense Wernicke and Brocka got it right but we've certainly learnt that the details are different in the sense that the areas that are crucial for language function are more focal than we thought, there's more individual variability than we thought between them, there's more sub divisions than we thought.
For me, the bonobos at Georgia University provide the strongest evidence that Ianguage doesn't necessarily require special processes unique to the human brain.
They can't speak, so they've been taught to link written symbols with specific words.
Look here it says Panbanisha, that's you.
The cooler, the foot cooler is hiding at the river.
Thank you bunny Panbanisha began with a few simple symbols We had the names of six different foods, a location outdoors, and a specific activity, grooming We added some other things, for example one of the words we added was the word quiet, which is a fairly abstract term.
Panbanisha when she was about three and a half years old she used the word quiet for the first time with me, and it was one night when I was pretty upset with something she was doing, and I was kind of giving her a lecture, in a very loud tone of voice that we should not be doing that right now, and Panbanbisha went to the keyboard and very quietly just looked at me with a very serious expression and she said quiet.
Perrier, Panbanisha That's right Panbanisha, you found Perrier.
Very, very nice.
Oh you're showing me again.
Panbanisha has now learnt the meaning of over 200 symbols.
Panbanisha can you find egg.
-Oh good -Very good -TV Panbanisha -Yes, that's right.
Most impressive of all, she even seems to appreciate the importance of word order.
You want juicy juice, all right, would you give a bite of your hot dog to the doggy please Would you give him some of your hotdog.
You can have more.
Panbanisha, please give the doggy a bite of your hotdog.
One bite Thank you very very much.
Even though you didn't want to do that, that was really nice.
Now if you think about how to teach Panbanisha a sentence like that you find yourself in kind of a quagmire, because dog is used in many different ways - it's used in the word hotdog and it's used in the word dog.
And if you think about the word hot, well the dog could be hot or the hotdog itself could be hot, or the hotdog could be cold but still called a hotdog.
Can you put the toy snake on your hand Sue Savage-Rumbaugh is convinced that bonobos can understand spoken English as well as a human child.
Their comprehension is at least between that of a 5 and 7 year old, maybe higher in some cases.
That's the subjective impression that one has in working with them.
Could you put the gorilla mask on Go ahead put it on your head.
Can you scare Paula.
They can comprehend entire dialogues, they can comprehend extensive narratives, they can understand stories about things that happened elsewhere, or stories about something that happened the previous day, if they're interested.
You're very tired, your eyes The researchers here believe that we and our ape cousins both have brains which can acquire language as part of a natural upbringing.
I think that the idea that our brain is the only brain capable of language on the planet is now something that's completely open to question.
I can accept that chimpanzees are capable of learning the rudiments of language, but there is a difference between us and them.
We humans have a universal ability to use complex language as a way of life.
So where does the difference lie? Are the superior language abilities that we possess purely the result of having bigger brains than chimpanzees? Recently the team here in Georgia have begun a series of experiments which may one day answer that question.
Onion For half an hour Pansy matched symbols to spoken words.
Then she was taken to a brain scanner to measure which areas of her brain had been most active during the simple language task.
Shoe, where's the shoe? Then John was scanned after doing the same thing and the two results were compared.
As expected, in the human, the activity is mainly in the left hemisphere, around the known language regions.
But in the chimpanzee there's a much more symmetric pattern across both halves.
These results are from just one chimp, but there seems to be a fundamental difference in the degree of brain symmetry.
A few miles away, researchers at Yerkees Primate Research Centre have been studying another aspect of brain symmetry in a different colony of chimpanzees.
These food tubes smeared with peanut butter provide a simple way to measure whether a chimp is consistently left or right handed.
The results suggest that our ancestors brains became more and more skewed to favour the right hand.
With humans the most extreme of all.
Offer a human being something to hold and most of us will reach out with our right hand.
In tasks involving manual dexterity we're almost all much better with one hand than the other, and this extreme handedness may reflect something very profound about the organisation of our brains.
Increasingly, we're discovering that many cognitive skills, as well as physical abilities, seem to be handled predominantly by one side of the brain or the other Human handedness is an outward sign that somehow our left and right hemispheres have become specialised.
Effectively we're all walking around with two slightly different half brains inside our heads.
And the benefit that this brings to us might ultimately be much more important that mere brain bulk.
Take the remarkable case of Joe known as JW in the scientific literature.
To control crippling epileptic fits, the main connections between the two sides of his brain were severed.
Joe's split brain allows researchers to explore the workings of the left and right hemispheres which are now almost completely separated.
His party trick is to draw two different objects simultaneously.
Susan why don't you try it.
I was dreading that! OK as long as Joe promises not to laugh at me.
OK, you ready? Draw them simultaneously as fast as you can Oh gracious! Over 30 years work with split brainers has convinced Mike Gazzaniga that asymmetry is the key to understanding our mental abilities.
To him intelligence comes only from the left Take a split brain patient and you measure their pre operative lQ and problem solving skills, and what have you, and then you split the brain, where you've now disconnected the two hemispheres, and you go back and measure the left hemisphere's problem solving, verbal lQ and it doesn't change a wit.
The right hemisphere on the other hand is sort of dumb.
But when he tested Joe's ability to recognise visual patterns, he was surprised how poorly the left performed.
These are called illusory contours The white discs create the illusion of a black shape which either curves inwards or bulges out.
Both sides of the brain can tell the difference.
But add a line inside the disc and the illusion of a shape is harder to see.
Unexpectedly Joe's left hemisphere is totally stumped All of a sudden the right hemisphere could do this test, still judge whether the rectangles were thin or fat, but the left hemisphere just fell apart, could not do the test.
It turned out that a similar test had been tried once before - on mice.
Astonishingly the human's giant left hemisphere failed to distinguish two patterns that the tiny mouse brain could tell apart.
Does this failure shed new light on the evolution of advanced human abilities? Maybe the left hemisphere begins to mutate in order to develop language, and as language requires more cortex and more cortex, perceptual processes that used to be in the left hemisphere sort of get squeezed out.
Gazzaniga's theory, is that as we evolved our left hemisphere acquired more and more advanced cognitive functions.
While our right changed very little.
And he believes that this half is just an evolutionary relic.
In fact if you look at the great skills we have that the chimp doesn't have there's every reason to believe that they're largely in the left hemisphere, that they're an outgrowth of some changes that must have occurred through mutations to the left cortex.
I accept that we're an asymmetric species, but I don't believe that there's a complete division of labour between left and right.
I don't go for the popular cliches about creativity and art coming from the right hemisphere with the left being literal and logical.
Instead I'm sure both our specialised half brains are involved in everything we do.
We're the fusion of two different interpretations of the world inside one head But there's one final missing ingredient to complete the transformation from the chimpanzees' range of skills to our own.
Three hundred thousand years ago the first full grown humans appeared with a full sized human brain.
But these neanderthals were not like us, and if evolution had stopped here human civilisation would still be in the Stone Age.
For many years archaeologist Steve Mithen has been studying the tools our ancestors left behind.
Trying to gain insights into how their minds worked.
So this is a small hand axe, as typically made by neanderthals.
You can see some very fine flake scars where a piece of flint had been removed by striking with a hammer stone.
Which are excellent butchery instruments for cutting through hide and sinews and tendons.
So they really are very skilled? They are, they're tremendously skilful work, there's nothing really modern humans are making which is more skilful in terms of tool making.
But neanderthals appear to have been astonishingly unimaginative, making the same stone tools for hundreds of thousands of years.
It's a rather little odd sort of behaviour looking at it from a modern human perspective, cos we normally think that the ability to make technically demanding things goes hand and hand with the ability to invent new types of tools, and to innovate and to create and continue improvements, technology.
Steve believes that the same tunnel vision that held back the neanderthals tool making might also have restricted their linguistic abilities.
I suspect neanderthals had words for flowers and I expect they had words for their children, but I don't think a neanderthal could ever come up with a phrase like my daughter is as pretty as a flower.
-I think -It's a creative thought.
It is in a way, and what you're doing you're drawing on one type of knowledge about people and children and you're drawing on another type of knowledge about flowers, and somehow you're making a new statement by drawing those two things together.
Suddenly with the arrival of modern humans new kinds of tools appear.
For the first time these humans try using bone and antler, as well as stone.
Neanderthals used bone, but they didn't carve it or manipulate it or change it at all.
Whereas modern humans started working bone and they carved it into harpoons and points and needles, and jewellery, all sorts of things.
And this really shows a big change from that tunnel vision way of thinking.
Because now they're taking technical skills which had been used for working wood and stone alone and applying it to a brand new material So they're changing what was part of an animal into something fundamentally different.
This revolution in tool making marked a crucial change in mental abilities, which launched us on an accelerating journey of technological development.
What seemed to happen is it snowballs, so you go from a very traditional hunter gatherer life to a world in which people are making art and clearly have got religious ideologies, making very complex artefacts, using body decoration, and they go through that in the lce Age and as soon as the lce Age finishes people invent agriculture and we move very rapidly to towns and cities and civilisation So all this was the result of our ability to see one thing in terms of another, to think laterally.
It's a fascinating idea, but we'll never know what actual changes in the brain were required to achieve the modern human mind.
It seems that the gradual evolution of the brain over millions of years merely equipped our ancestors with an array of modular mental abilities, then suddenly these distinct functions merged and our lives were transformed.
There was an explosion of creativity and imagination that put us where we are today.
We humans, unique among animals can gaze at the planet we now dominate.
In the next programme we explore the extraordinary way in which your brain is constantly changing as you go through life, how everything you experience shapes your mind.