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00:00At the start of each day, a profound change happens in the brain of every human being.
00:20As we wake up, an inner world comes to life.
00:24You become conscious.
00:31From the massive nerve cells that have been ticking over while we were sleeping, a strange
00:36new sensation emerges.
00:38The first-hand feeling of being a conscious human being.
00:45Somehow your brain creates the intangible, indescribable experience of being you.
00:51It's not something most of us ever stop to really think about, but the fact that we each
00:57have an inner world of feelings and experiences is, for me, even more extraordinary than the
01:03fact that living things evolved at all.
01:06As a scientist, I cannot accept that consciousness is something mystical, beamed into our heads
01:11from outside.
01:12It has to come from physical processes within the brain.
01:17But the question is, how?
01:19The
01:43ultimate goal of neuroscience is to interpret all our everyday experiences in terms of measurable
01:49changes in brain activity.
01:51So where do we begin with something as elusive as consciousness?
01:55Something so utterly subjective and unique to each individual?
02:01The challenge is to explain how a kilo and a half of neurons and blood vessels inside
02:06our heads, with the consistency of soft butter, can generate the extraordinary, rich range
02:12of conscious feelings that we experience.
02:15From the taste of a good cup of coffee, to the satisfaction of solving a crossword puzzle,
02:20to the warm glow of remembering a summer's holiday on a cold winter's morning.
02:25We take it for granted that the brain makes being alive feel the way it does.
02:29Yet there's no reason why it should.
02:32The brain is made of the same biological ingredients as the rest of the body.
02:36Yet somehow it manages to generate the indescribable phenomenon of consciousness.
02:41Explaining this tantalising paradox is, I think, the ultimate quest for science.
02:52Let's start as simply as possible.
02:55We're always conscious of something.
02:57What determines what it will be?
03:02Take driving.
03:04You're going along a route you do every day.
03:07Changing gear and adjusting your speed and direction, and you're not aware of any of it.
03:13You're effectively somewhere else.
03:22Then suddenly something happens, and it becomes the focus of your consciousness.
03:29Something switches inside the brain, and the actions that were done automatically are now
03:35at centre stage.
03:38So what is happening in the brain when you switch out of autopilot
03:43and become actively aware of driving?
03:48Could there be some kind of higher control centre in the brain
03:53that determines what you're going to be aware of?
03:56Is there some kind of brain HQ which oversees all the activity in the rest of the brain?
04:05If so, this centre for consciousness would direct the different processes going on down below.
04:12Whatever it happened to select at that particular moment
04:15would be the focus of your consciousness.
04:20So is there any evidence that we have a consciousness control centre in our heads?
04:26One man's brain has played an important role in answering this question,
04:31and it can often be found in the gardener's arms in Chester.
04:43Graham Young has a very unusual brain, and scientists are so keen to study it
04:49that he's regularly flown expenses paid all over the world.
04:54It's almost a different life.
04:56I live in Chester, and I work in Chester, and I go away doing all this stuff,
05:01and it's almost like a separate identity.
05:04It's a bit strong, but it's two different existences.
05:11Graham became a hot property for neuroscientists
05:14as a result of being hit by a car when he was a child.
05:20I had a road accident when I was eight, resulting in some brain damage.
05:24So I lost all my vision to the right in both eyes.
05:28As far as he was aware, he was completely blind on the right-hand side.
05:35I mean, I literally used to be walking around town as an eight-, nine-year-old lad,
05:38and I'd walk into a lamppost or into a bin.
05:41I just didn't see it, and we'd just walk straight into it.
05:44I mean, that doesn't happen any more.
05:46I've just got used to just having a half-filled view.
05:5112 years later, while he was having his eyes tested in London,
05:56they discovered something extraordinary.
05:59It turned out Graham's brain could actually process visual information
06:03on both sides, even though he wasn't aware of it.
06:08Graham is a perfect case of a fascinating condition called blindsight.
06:14Now, most people don't get brain damage in such a way as to say
06:18satisfy the research scientist.
06:21Graham, fortunately, has damage largely restricted to the visual cortex
06:27and not to the rest of the brain.
06:31So that makes it...makes it a much more pure case.
06:38Graham's road accident destroyed just a small area at the back of his brain.
06:44If losing this area caused him to lose awareness of seeing,
06:47could this damaged area be the seat of consciousness?
06:53Weisskranz experimented further.
06:56He showed Graham moving lights on his blind side.
07:01Right, unaware.
07:03Left, unaware.
07:05Right, unaware.
07:07Bizarrely, although Graham says he can't see them,
07:11he can guess correctly what direction the dots are moving in.
07:15Right, unaware.
07:17I am completely unaware of an event occurring in my blind field,
07:21and yet, in terms of which way it's moved, I get it right 90% of the time.
07:25That's a bit strange, isn't it?
07:27And I don't know how I do it.
07:29Right, unaware.
07:31Blindsight is a condition in which one can respond to visual events
07:37without being aware of them.
07:39OK?
07:41Now, that means that, as you know what the brain damage is,
07:45you can start to say something about what areas of the brain are necessary,
07:49are critical for awareness.
07:53So what is going on inside Graham's brain?
07:57Scans suggest that when Graham is responding to the dots,
08:01but isn't aware of them, a very primitive visual pathway is active.
08:05But when he is actually seeing them,
08:07a whole new range of brain regions lights up.
08:16We need lots of different areas for consciousness.
08:21Just to receive the information isn't sufficient.
08:24You have to do something with it to become aware.
08:27And the regions of the brain that are important for that
08:31lie quite far removed from the visual cortex, in the frontal lobe,
08:36involving those regions of the brain that allow us to communicate
08:41the fact that we are conscious, that we are aware.
08:50Blindsight has revealed that there's far more to being aware
08:55than a single central control centre.
09:01Instead of some special area devoted to consciousness,
09:05somehow the extraordinary feeling of awareness
09:08emerges from ordinary brain activity.
09:17It may not feel like it, but changing patterns of nerve cells
09:22firing in the brain are the basis of everything we experience.
09:28Everything we imagine, all our thoughts and feelings.
09:39Conscious awareness, then, must somehow arise
09:43from this maelstrom of electrical activity in the brain.
09:49So what could explain which of the many networks of cells
09:52firing away in our heads is heard above the background chatter?
10:09Neuroscientists are now squaring up to the big question.
10:15Which special property or process in the brain might cause consciousness?
10:33If there is no special centre in the brain whose job it is
10:36just to generate consciousness, then somehow it must arise
10:39directly from the activity of ordinary brain cells.
10:42But then we have a problem.
10:44In the brain there are thousands of networks of neurons all firing away.
10:48What special property could a network of neurons suddenly acquire
10:52that's just for a moment made it responsible for consciousness?
11:01Imagine that your brain is like the surface of a lake
11:04in the rain.
11:06Each new event is like a raindrop,
11:09which triggers a spreading wave of nerve cell activity,
11:13which then gradually fades away.
11:20I'm suggesting that we're conscious of whatever happens to have caused
11:24the biggest ripple of activity in our brains at any one time.
11:29I think of consciousness as something that grows,
11:32as a spreading wave grows.
11:34The stronger or more significant the stimulus,
11:37the more extensive the ripples of activity,
11:40the more all your neurons are working together.
11:43So the conscious thoughts and feelings that flit through your head
11:47are a direct reflection of what's going on in your brain.
11:51The more you're aware of what's going on in your brain,
11:54the more conscious thoughts and feelings that flit through your head
11:57are a direct reflection of the ever-changing pattern of activity
12:01in your brain.
12:05One attraction of this idea is that it might help explain
12:09one of the great unsolved medical puzzles.
12:13What happens to the brain when we lose consciousness
12:17through anaesthesia?
12:24Good morning, Dr Artusio. I hope we're on time.
12:26Good morning. Yes, we're a few minutes yet.
12:29Dr Mazeer, would you go ahead and prepare this patient
12:32and I will join you in the induction room in a few moments.
12:36No-one knows how anaesthetics rob the brain of consciousness,
12:40even though they've been used for many years.
12:43Brain scans have shown that there's no obvious single area
12:47that's shut down.
12:49Somehow, anaesthetics must affect the whole brain.
12:53Can you hear my voice?
12:59We have now made the transition into surgical anaesthesia.
13:04Dr Belville...
13:08But the really interesting issue for me is that the effects are gradual.
13:12It's like a sort of dimmer switch.
13:17We usually take the patient through the analgesic stage,
13:21through the loss of consciousness,
13:23and through a delirium phase into surgical anaesthesia.
13:28In some intriguing studies in the 1950s,
13:31Dr Joseph Artusio investigated the semi-conscious state.
13:36Edna, are you comfortable now?
13:39Edna, are you comfortable now?
13:42Nod your head, Edna, if you're comfortable.
13:46You see, Edna nodded that she was comfortable.
13:49We have now entered the true third plane of the first stage.
13:55Artusio was exploring the possibility of conducting major surgery
13:59without the complications of high levels of anaesthetics.
14:04Here, he manages to find a dose
14:06which produces an astonishing semi-aware state,
14:10where the patient feels no pain,
14:12but yet she can still respond to commands.
14:20So what could explain this gradual loss of consciousness?
14:25All anaesthetics dampen down electrical signals between brain cells.
14:30According to my theory,
14:32this would stop the waves of activity from spreading so far.
14:36As the assemblies of cells become smaller,
14:39our consciousness gradually dims.
14:45But anaesthetics also offer a further clue.
14:49At doses too low to rob you of consciousness,
14:52they can nonetheless dramatically distort it,
14:55producing hallucinations.
14:57DRILL WHIRRS
15:16In Zurich, Dr Franz Wollenweider is studying
15:19how low doses of an anaesthetic called ketamine can affect the brain.
15:24Ketamine can enhance your mood.
15:26It can give you feelings like euphoria.
15:30It changes all the sensory modalities.
15:35You can, for instance, hear vision,
15:37or you can visualise things that you can't see.
15:41At first you have illusions, then maybe you have hallucinations.
15:45You can see things that do not exist in the real world.
15:53Phew.
15:57Well, now it's coming.
15:59It's coming now.
16:00Yeah, definitely taking off.
16:03Are you able to close your eyes and focus on your inner experience?
16:08On my what? Inner experience?
16:19The challenge for any theory of consciousness
16:22is to explain how minute doses of an anaesthetic
16:25can produce such distorted experiences.
16:40Yes, everything is very different than usual.
16:46The visual effect and the audio effect, they are connected.
16:51They're melted.
16:52Yeah, they're melted.
16:57Is vision more auditory experience and vice versa?
17:01Yeah, one gives the other food.
17:05That's it.
17:06As I see it, the inputs from his senses would normally dominate his brain,
17:11creating a large spreading wave of nerve cell activity.
17:15The drug might weaken the signals coming from the senses,
17:18leaving a hectic jumble of smaller ripples of activity
17:21spontaneously generated in the brain, producing hallucinations.
17:25Movie in the movie in the movie, or box in the box in the box, or whatever.
17:29I had this experience like I was...
17:34The space was controlling...
17:37No.
17:39My brain was controlling my brain was controlling my brain anyway.
17:44Volunteers have been scanned while they're hallucinating.
17:48Over several minutes, a slight change in activity shows up in the front of the brain.
17:54But this time frame is too long.
17:57Consciousness is too fleeting for the subtle and transient changes in cell activity
18:02to be detected by this kind of approach.
18:09We think that ketamine directly interferes with the communication between nerve cells
18:14and on ketamine this communication is changed.
18:17Some cell communication is blocked even.
18:21And ketamine may lead to new assemblies between the nerve cells
18:27so that a different kind of network gets established on ketamine
18:33that is normally not working in that way.
18:39And according to your experiences, what do you all see?
18:43Oh, what I did today, yeah, I travelled through the galaxy.
18:59Manipulation of conscious experience with drugs is nothing unusual.
19:03We do it all the time with alcohol, nicotine and caffeine.
19:08But drugs don't have to be involved.
19:11I've come to the Palladium in Edinburgh to watch a group of performers
19:14who claim to have a unique ability to control the degree to which they are conscious of pain.
19:21This is not the sort of thing I'd normally go for, but I have to say I'm quite excited at the prospect
19:25because I gather I'm going to see people putting themselves through enormous agonies
19:29but apparently completely unperturbed.
19:31I'm going to be driving around in my car,
19:34but apparently completely unperturbed.
19:36I'm going to be looking for whether I can apply my theory of consciousness
19:40to what I'm actually seeing before my very eyes.
19:59The circus has gained something of a cult following over the last ten years.
20:03It is the extraordinary feats of self-mutilation.
20:11What I want to know is what's going on in their brains.
20:15How can they block out what, to me, would be unbearable pain?
20:19This is not a group of people talking out of sorts.
20:22Who are you?
20:23She doesn't know.
20:24He got it, he got it.
20:25You're walking on a red light.
20:26Walking on a red light.
20:29Jim Rowe Circus is really dealing a lot with how to use your mind and your brain to empower yourself.
20:35We do it as a warped seminar.
20:37It's kind of a comedy.
20:39Bebe the Circus Queen, the amazing Mr. Lifto, and myself,
20:44we basically kind of explain how to circumvent or to overcome what we would call discomfort.
20:53I think you might, a lot of people might call pain.
20:57Bebe's going to lie on this bed of nails, have a glass plate placed onto her stomach,
21:02and a cannonball will come down, crashing and smashing the glass.
21:06A lot of people do the bed of nails, and there is discomfort there.
21:13Measure anything?
21:15Bebe's real fear is the shattering of that plate, because it's random.
21:20And that's something that you can't prepare for.
21:28Yes! Take a look at her back! Take a look!
21:31Watch and register the shock!
21:34Thank you, Bebe, you've got to love it!
21:36It seems that the way they control the pain is by preparing their mind for what's to come.
21:42We all, throughout the circus, use the same way of dealing with discomfort.
21:49For example, if I'm doing the human dartboard,
21:53I put myself, I literally take my mind, which takes its body, into another place.
22:01Now, where I like to go is into a nice, warm, watered pool.
22:06And I like to be right up to my neck, and everything's feeling fine.
22:11Everything's all nice and warm and relaxed.
22:15With just a plank of wood...
22:17Jim deliberately fills his mind with a persistent mental image to block out the pain.
22:23I can take another one Edinburgh! Can you?
22:27My interpretation is that a large assembly of cells in his brain
22:31generates Jim's overwhelming feeling of being in a warm pool.
22:37This assembly is so dominant, it shuts out any rival stimulus, like pain.
22:42I feel nothing! Oh, I just felt something!
22:45I don't feel the pain.
22:47But you see, it's different now, because I'm expecting what's happening.
22:51If I stub my toe on my bed or something at night, I'm going to scream just like you.
22:58Because I didn't expect it, and I didn't put myself in the warm water.
23:02What's your name?
23:03Susan.
23:04I almost really screwed that up.
23:06Susan, from the BBC, give her a big hand.
23:09There you go, Susan. Now then, this is how I shave.
23:16Of course, we don't actually know what the brain cells are doing inside Jim's head.
23:20My idea is still only a theory.
23:23On his head, on his head.
23:25OK.
23:26Come on.
23:27Stand up.
23:28Oh, it's the lowest point of the tube.
23:35Oh, hell no!
23:42Thank you, Susan. Give it up for Susan. She's a star. Thank you.
23:46We may not know the exact brain process which gives rise to consciousness,
23:50but we do know that it must be produced by ordinary brain cells.
23:54In other words, it must arise directly from subconscious mental activity.
23:59And that has profound implications for how we view
24:02what it means to be a human being.
24:04What do you fear?
24:19We know that when we need to, our brains can trigger reflex responses
24:23without any conscious thought at all.
24:25When facing a serve of over 100 miles an hour,
24:28professional tennis players don't have time to mull things over.
24:31Their complex judgements and tactical decisions
24:34are all made automatically in the subconscious.
24:40I can tell you about what happened to me.
24:42I mean, I just take a look at the ball.
24:44I can see where my opponent is and just hit the ball and...
24:47I mean, sometimes you don't even have the time of thinking
24:49and you just have to hit the ball and that's it.
24:52On a hard court or on grass, you won't see many shots.
24:56I mean, that's why you won't ever think.
24:58I mean, you hit the ball and the other side where you see the player,
25:01and that's it.
25:03If they try to become aware of what they're doing, they will fail.
25:08The great players will serve the ball at about 100 miles an hour.
25:12The only thing the opposing player remembers that he can tell you about
25:18is watching the angle of the serve.
25:21So they're unconsciously carrying out that fast function.
25:30Neuroscientist Professor Benjamin Libet
25:33has spent the last 50 years fascinated by the subconscious.
25:47My own belief is that all our thoughts and all our actions
25:51are initiated unconsciously.
25:54Any thought you have proceeds very rapidly unconsciously
25:59and finally you become conscious of some result.
26:05In 1958, Benjamin Libet began a series of experiments
26:09that challenged one of the basic tenets of human existence,
26:13that we are free to think whatever we choose.
26:18Occasionally, brain surgery has to be conducted on patients
26:22while they are awake.
26:24Benjamin Libet realised that this gave him a unique opportunity
26:28to experiment on the conscious human brain.
26:36We did not use general anaesthesia.
26:39We used a local anaesthetic for cutting open the skin
26:43and drilling a hole in the skull.
26:47And the subjects were very cooperative in general.
26:52He began with a simple query.
26:54How long would the patient's brain have to be stimulated
26:57with an electric current before they became aware of it?
27:01We started by stimulating the sensory cortex,
27:04which is known to produce a sensation in a proper part of the body,
27:09usually the hand in our case,
27:11and to ask the subject if they felt anything
27:15and what they felt and so on.
27:18He discovered that the brain had to be stimulated
27:21for at least half a second
27:23before the patient reported that they felt anything.
27:26It seems it takes this long
27:28for the brain to generate a conscious experience.
27:31That means that you do not experience the environment when it happens.
27:36There's a delay of about a half a second before awareness is produced.
27:42This first experiment was proof
27:44that fast reactions must all be carried out subconsciously.
27:48If you're driving a car and somebody steps in front of it suddenly,
27:52you'll slam on the brake in much less than a half a second,
27:56and that's undoubtedly unconsciously performed.
28:00If you had to wait for the half a second, you're liable to hit the person.
28:04The idea of living half a second in the past may seem strange.
28:09But if consciousness depends on large numbers of cells working together,
28:13it makes sense that it takes time to develop.
28:19It was his next set of experiments that caused a real controversy.
28:23This time, he had a different question.
28:27Does the brain start first or do you start the brain?
28:31Because the traditional way of looking at voluntary action or free will
28:37is that you want to do something and you tell the brain to get going.
28:44The results of his work have been debated for years.
28:47Benjamin Libet may now have retired from the fray,
28:50but others are continuing his work.
28:55We all have this very strong belief that we have conscious free will,
28:59and it's a central part of our idea of ourselves as individuals
29:04that we can want to do something, we can have an intention to do something,
29:08and then we can do it.
29:10We can make our intention drive our actions.
29:13And Benjamin Libet's work was one of the few experiments
29:16which made a truly innovative and courageous attempt to address that question.
29:20I can't feel it being cold.
29:22Patrick Haggard's team are going to measure my brain activity
29:25in the run-up to a conscious decision, with electrodes placed on my scalp.
29:30OK, Susan, you're all wired up and ready to go.
29:34Absolutely.
29:35We're going to record from your left motor cortex,
29:38your right motor cortex and from the midline.
29:41I want you to watch the clock hand,
29:44which is rotating in this small clock in the centre of the screen.
29:48And then at any time that you choose, when you intend and will to,
29:54I want you to press either the left or the right button.
29:58I want you to press either this key or this key.
30:02As the urge... As the urge takes you.
30:04Fine, OK.
30:05And then the computer will prompt you to type in the position of the clock hand
30:10at which you first felt the conscious will to press the button.
30:16Good. Any questions? No.
30:18Off we go.
30:22It's very funny waiting for the urge, isn't it?
30:28So watching the clock, I record the exact time that I make the decision to act,
30:33while the electrodes on my head monitor the activity in my brain
30:36leading up to this decision.
30:55As I do this over and over again,
30:57a clear pattern starts to emerge.
31:21So here are our results,
31:23which contain the same basic effect as Libet originally found.
31:27The average time of the intention to move was where this arrow is here.
31:33And you can see that the motor areas of the brain
31:36have begun to build up electrical activity
31:39in preparation for this willed action,
31:422,000 milliseconds at least, before the action actually occurs.
31:49Just as in Libet's original work,
31:51this experiment seems to show that my brain begins to prepare for movement
31:56long before I felt like I had consciously decided to move.
32:00So did I have any real choice about when I moved?
32:04Could the feeling of having made a decision just be an illusion?
32:10So this looks like a real problem for our idea of conscious free will,
32:15because our assumption that we work with every day, I think,
32:18is that we decide what we want to do,
32:21and then, or I should say I decide what I want to do,
32:24and then I am able to get my brain to drive my body to make it happen.
32:34The implications of Libet's findings are far-reaching.
32:38That our conscious mind, our free will, is merely an after-effect.
32:49The actions and decisions we take every day,
32:52which feel like instant conscious choices,
32:55are actually the result of slowly emerging subconscious processes in the brain.
33:02If everything really starts in the subconscious, do we have any freedom?
33:07Or are we sophisticated machines,
33:10our responses determined by the mechanics of our brains?
33:18There's no question that we are all in the same boat.
33:22We're all in the same boat.
33:25We're all in the same boat.
33:29There's no question that we are organic machines.
33:32If we think of a machine as any physical system
33:35capable of performing certain functions,
33:38then, of course, the brain is a machine,
33:40and we are, our whole bodies are biological machines.
33:44But the point I'm making now is that doesn't show that we don't have free will,
33:48because this is a, the peculiarity of these machines
33:51is that they are conscious machines.
33:55Since the 1960s, philosopher John Searle
33:59has been a passionate campaigner for free speech.
34:04He believes that freedom,
34:06whether at the political or the personal level,
34:09is an absolutely fundamental part of what it means to be human.
34:13Now, here's the problem.
34:15There isn't any way we can think away freedom.
34:17That is, when you make a decision, when you undertake any action,
34:20you have to presuppose freedom.
34:22If you go in a restaurant and they give you the menu
34:24and the guy wants to know what you want,
34:26you can't say, oh, well, I'm a determinist,
34:28que sera, sera, I'll just see what I order,
34:31because even that is an exercise of freedom.
34:34The refusal to exercise freedom is already an exercise of freedom.
34:40When you think about the things that some people do,
34:43there's no getting away from the fact
34:45that consciousness seems much more like an active force
34:48than a mere after-effect.
34:53Mr Liftoe is almost the living embodiment of free will at work.
35:06But do our minds really give us total freedom
35:09to control our thoughts and actions?
35:23Ooh!
35:33It feels as though we've got free will.
35:38But how could a brain made of ordinary matter
35:41give rise to a mind
35:43which floated totally free from physical reality?
35:48So here's where we're at.
35:51So here's where we are at this stage of intellectual history.
35:54We've got this awful problem of free will,
35:56and people are refusing to look at it
35:58the way they were refusing to look at consciousness 20 years ago.
36:01But if you're looking at consciousness,
36:03you've got to look at free will,
36:05because it's one and the same set of problems.
36:07There's no way we can think away our own conviction of free will.
36:10We cannot abandon it.
36:12It's a necessary presupposition of just living on a day-to-day basis,
36:15but we can't square it with the rest of the things we believe.
36:18So we've got a straight contradiction
36:20in every intellectual's conception of how the world works.
36:24That we've got to resolve.
36:28In the backwoods of New Hampshire,
36:30Joe, known famously as the case of JW,
36:34has inspired some thought-provoking ideas
36:37about where the illusion of free will comes from.
36:4120 years ago, Joe decided to submit himself
36:44to a drastic operation to control his epilepsy.
36:49Yeah, one day he'd have two or three different seizures.
36:52And why you do that long enough
36:54when you're willing to go through anything?
36:57So what the heck?
36:59They want to crack your head open and have an operation.
37:02What have you got to lose? Everything's going wrong anyway,
37:05so might as well go for it.
37:07So I just went for it anyway.
37:09I thought, well, I'll try and see.
37:11And it turned out it worked good.
37:15The operation was to split his brain in two.
37:21Having exposed the top of the head,
37:23the surgeon works his way into the cleft between the two hemispheres,
37:27revealing the white bundle of nerve fibres
37:29connecting left and right sides of the brain.
37:32OK, Dave, I'm going to start to divide the corpus callosum.
37:35Tearing apart these 50 million fibres in the corpus callosum
37:39prevents epileptic seizures from spreading from one side to the other.
37:43But it also prevents almost all information from the senses
37:47travelling across.
37:52The operation has made Joe a valuable research subject
37:55for neuroscientists.
37:57After years of studying split-brainers,
37:59Professor Kazaniga believes he may have found
38:02the source of the illusion of conscious free will.
38:06Good. OK. You ready?
38:08He started by examining the linguistic abilities
38:11of the left and right sides of the brain.
38:14Storm.
38:16Words on the right of the screen go to his left hemisphere
38:19and he calls them out easily.
38:22Gun. Good.
38:24But when words are flashed to the other hemisphere...
38:28Didn't see.
38:30He says he didn't see anything.
38:32But, remarkably, he then draws a picture of the word.
38:41Joe draws the telephone his right hemisphere saw,
38:44but, strangely, he can't tell what it is.
38:48Shoe. I don't know what it is. I can't tell.
38:51Number. Good. Whatever it is.
38:54I can't exactly tell what it is.
38:57I can't exactly tell what it is.
38:59It looks like a shoe, I guess.
39:02What else?
39:04Coffee. I don't know. I can't tell what it is.
39:07Because he thinks that speech comes from the left hemisphere,
39:10Mike Kazaniga believes that the left
39:12must also be dominant in generating consciousness.
39:16If you think about the consciousness differences
39:18between the left and the right separated hemisphere,
39:21the left hemisphere is an interesting cognitive machine.
39:25It has all these problem-solving capacities,
39:27and talk, and language, and speech, as you saw.
39:29And the right hemisphere basically isn't a very interesting entity.
39:33You would not want to have a date with the right hemisphere.
39:43Despite having his brain split in two,
39:46Joe's life has been remarkably unaffected by the operation.
39:50His personality and his interests have remained the same.
39:56I've had them down there since I was a little boy.
39:59And I've been building them and saving them.
40:02They've kept right with me all the time.
40:06I've been pretty much like the same person like I've always been.
40:09Just chopped up a little different, that's all.
40:12As far as the operation goes,
40:14I don't think it really affected me too bad.
40:16It just helped.
40:18But I don't think as far as making it worse, making me worse,
40:20I think it didn't do anything.
40:22As far as two brains, I only got one brain.
40:24It's just not quite the same design as everybody else's.
40:30The theory goes that if the conscious feeling of who you are
40:33came from both hemispheres,
40:35then Joe would feel changed by his operation.
40:39Since he doesn't, Mike Gazzaniga's bold conclusion
40:42is that Joe's inner voice must come from just one side of his brain.
40:48And since our inner thoughts are all in words,
40:50they must come from the linguistic left.
40:54The inner voice in the left hemisphere has got to be huge, robust.
40:58It's Pavarotti-like.
41:00And this right hemisphere probably has a chirp, a little bird sound,
41:05because the devices that allow for the inner voice
41:09to really expand and express itself
41:12are mostly located in the left hemisphere.
41:16Experiments on Joe have led Mike Gazzaniga to believe
41:19that the left hemisphere may also provide an explanation
41:23for the sensation of free will.
41:31What did you see?
41:32Dial.
41:33Is that a dial?
41:35In this test, Joe is flashed two words simultaneously.
41:39Tell me what you see, OK?
41:41Here we go.
41:49Shown hour and glass, he draws an hourglass.
42:01With his left hemisphere, Joe names it immediately.
42:04What's that?
42:05Hourglass.
42:07Good.
42:09But Joe's left only processed the word glass,
42:12so he goes on to invent a reason why he drew a timepiece.
42:16Did you see it? What did you see?
42:18I just saw a glass.
42:20Why did you draw that?
42:22I don't know.
42:24Huh?
42:25Probably still thinking about the clock on that.
42:28It's as if Joe has been fooled by his own left hemisphere.
42:32And so he basically says,
42:35And so he basically makes up a story
42:37to explain the behaviour that he's carried out,
42:40and he comes to believe that that's the reason
42:43why he did a particular act.
42:45And you see those experiments, that kind of phenomenon,
42:48time and time again in these split studies.
42:51But the importance of it is not that it is unique
42:54to split-brain patients at all.
42:56It is a metaphor for what you and I do,
42:59is we're constantly trying to figure out
43:03and put a spin on what's coming out of our body.
43:11Gazzaniga believes he's discovered
43:13why we think we've got free will.
43:18The feeling of being consciously in control of our lives
43:21is just an illusion created by the left hemisphere.
43:25Our conscious inner voice is merely a fiction
43:28to explain decisions made by the subconscious.
43:33It's got to be true that a huge amount of what we do
43:37in our awake, conscious life
43:39is governed by unconscious processes.
43:42I'm not conscious about the fact
43:44that how that last sentence just came out.
43:46It just came out because it's being said.
43:49I'm not conscious about the fact
43:51that how that last sentence just came out.
43:53It just came out because it's being...
43:55Some guys are down there with framing hammers
43:57putting this stuff together, and bingo, out it comes.
44:00And it's more or less orderly.
44:02So just think about the fact
44:05that the major management of your body
44:09walking through space,
44:11your responding to auditory, visual, tactile events,
44:14all that's being done for you.
44:16It's just absolutely being done for you,
44:18and you're not paying any attention to it at all.
44:20You don't even know about it, but it does a wonderful job.
44:23And it just turns out that more and more of your cognitive acts
44:26are the same.
44:28The work with split-brainers like Joe is fascinating.
44:34But I'm not convinced that the experiments prove
44:37our consciousness emerges from just one half of our brains.
44:46And this research doesn't actually get us any closer
44:49to answering the most important question
44:52of how brain cells can generate consciousness at all.
45:05I think of the conscious thoughts and feelings
45:07that flit through your head
45:09as a direct reflection
45:11of the ever-changing pattern of activity in your brain.
45:15I'm suggesting that we're conscious of whatever happens
45:19to have caused the biggest ripple of activity in our brains
45:23at any one time.
45:32If I'm right, these patterns of activity
45:35would account for how the mass of protein and fat in our heads
45:39can create the richness of thought and feeling we each experience.
45:45We know there's no such thing
45:47as a consciousness centre inside our heads.
45:51Instead, it's a result of the overall state of the whole brain.
45:55And although it may feel special,
45:57consciousness must emerge from exactly the same processes
46:01as the brain's subconscious activity.
46:04We may not yet be able to understand
46:06how consciousness is generated,
46:08but now that it's accepted as a physical reality
46:11and not some mystical phenomenon,
46:13I think we are on the road
46:15towards a scientific understanding of this age-old problem.
46:26This new century will bring great advances
46:29in our understanding of the brain.
46:33As imaging techniques improve,
46:35we'll be able to monitor the brain's activity
46:38in all its complexity as it flits from thought to thought.
46:44And when we can match each of the many physical processes
46:47inside our brain with all our different thoughts, emotions and memories,
46:51the phenomenon of consciousness itself may eventually be laid bare.
47:02As we find out more about what goes on inside this incredible object,
47:06so our lives could be transformed,
47:08if we could discover why, when certain brain cells degenerate,
47:12memory and personality fade along with them,
47:15then we could combat some of the devastating problems of old age.
47:21And as we gain insights into the brain processes
47:24that are necessary for happiness,
47:26then we may have powerful new ways to treat depression.
47:31Whatever we learn about how the brain works,
47:34each one of us will continue to enjoy our own private world
47:38locked away inside our heads.
47:40I don't believe that neuroscience will ever undermine
47:43what it feels like to be a unique, individual human being.
48:04Transcription by ESO. Translation by —
48:34Transcription by ESO. Translation by —