0:00:00.000,0:00:04.000
Well, as Chris pointed out, I study the human brain,

0:00:04.000,0:00:06.000
the functions and structure of the human brain.

0:00:06.000,0:00:10.000
And I just want you to think for a minute about what this entails.

0:00:10.000,0:00:14.000
Here is this mass of jelly, three-pound mass of jelly

0:00:14.000,0:00:17.000
you can hold in the palm of your hand,

0:00:17.000,0:00:21.000
and it can contemplate the vastness of interstellar space.

0:00:21.000,0:00:23.000
It can contemplate the meaning of infinity

0:00:23.000,0:00:28.000
and it can contemplate itself contemplating on the meaning of infinity.

0:00:28.000,0:00:33.000
And this peculiar recursive quality that we call self-awareness,

0:00:33.000,0:00:37.000
which I think is the holy grail of neuroscience, of neurology,

0:00:37.000,0:00:39.000
and hopefully, someday, we'll understand how that happens.

0:00:40.000,0:00:43.000
OK, so how do you study this mysterious organ?

0:00:43.000,0:00:47.000
I mean, you have 100 billion nerve cells,

0:00:47.000,0:00:50.000
little wisps of protoplasm, interacting with each other,

0:00:50.000,0:00:54.000
and from this activity emerges the whole spectrum of abilities

0:00:54.000,0:00:57.000
that we call human nature and human consciousness.

0:00:57.000,0:00:58.000
How does this happen?

0:00:58.000,0:01:01.000
Well, there are many ways of approaching the functions of the human brain.

0:01:01.000,0:01:04.000
One approach, the one we use mainly,

0:01:04.000,0:01:09.000
is to look at patients with sustained damage to a small region of the brain,

0:01:09.000,0:01:11.000
where there's been a genetic change in a small region of the brain.

0:01:11.000,0:01:15.000
What then happens is not an across-the-board reduction

0:01:15.000,0:01:17.000
in all your mental capacities,

0:01:17.000,0:01:20.000
a sort of blunting of your cognitive ability.

0:01:20.000,0:01:23.000
What you get is a highly selective loss of one function,

0:01:23.000,0:01:25.000
with other functions being preserved intact,

0:01:25.000,0:01:27.000
and this gives you some confidence in asserting

0:01:27.000,0:01:31.000
that that part of the brain is somehow involved in mediating that function.

0:01:31.000,0:01:33.000
So you can then map function onto structure,

0:01:33.000,0:01:36.000
and then find out what the circuitry's doing

0:01:36.000,0:01:38.000
to generate that particular function.

0:01:38.000,0:01:40.000
So that's what we're trying to do.

0:01:40.000,0:01:43.000
So let me give you a few striking examples of this.

0:01:43.000,0:01:47.000
In fact, I'm giving you three examples, six minutes each, during this talk.

0:01:47.000,0:01:51.000
The first example is an extraordinary syndrome called Capgras syndrome.

0:01:51.000,0:01:53.000
If you look at the first slide there,

0:01:53.000,0:01:58.000
that's the temporal lobes, frontal lobes, parietal lobes, OK --

0:01:58.000,0:02:00.000
the lobes that constitute the brain.

0:02:00.000,0:02:04.000
And if you look, tucked away inside the inner surface of the temporal lobes --

0:02:04.000,0:02:06.000
you can't see it there --

0:02:06.000,0:02:08.000
is a little structure called the fusiform gyrus.

0:02:08.000,0:02:11.000
And that's been called the face area in the brain,

0:02:11.000,0:02:14.000
because when it's damaged, you can no longer recognize people's faces.

0:02:14.000,0:02:16.000
You can still recognize them from their voice

0:02:16.000,0:02:18.000
and say, "Oh yeah, that's Joe,"

0:02:18.000,0:02:21.000
but you can't look at their face and know who it is, right?

0:02:21.000,0:02:23.000
You can't even recognize yourself in the mirror.

0:02:23.000,0:02:26.000
I mean, you know it's you because you wink and it winks,

0:02:26.000,0:02:28.000
and you know it's a mirror,

0:02:28.000,0:02:31.000
but you don't really recognize yourself as yourself.

0:02:31.000,0:02:35.000
OK. Now that syndrome is well known as caused by damage to the fusiform gyrus.

0:02:35.000,0:02:38.000
But there's another rare syndrome, so rare, in fact,

0:02:38.000,0:02:42.000
that very few physicians have heard about it, not even neurologists.

0:02:42.000,0:02:44.000
This is called the Capgras delusion,

0:02:44.000,0:02:47.000
and that is a patient, who's otherwise completely normal,

0:02:47.000,0:02:50.000
has had a head injury, comes out of coma,

0:02:50.000,0:02:53.000
otherwise completely normal, he looks at his mother

0:02:53.000,0:02:56.000
and says, "This looks exactly like my mother, this woman,

0:02:56.000,0:02:58.000
but she's an impostor.

0:02:58.000,0:03:00.000
She's some other woman pretending to be my mother."

0:03:00.000,0:03:02.000
Now, why does this happen?

0:03:02.000,0:03:05.000
Why would somebody -- and this person is perfectly lucid and intelligent

0:03:05.000,0:03:07.000
in all other respects, but when he sees his mother,

0:03:07.000,0:03:10.000
his delusion kicks in and says, it's not mother.

0:03:10.000,0:03:12.000
Now, the most common interpretation of this,

0:03:12.000,0:03:14.000
which you find in all the psychiatry textbooks,

0:03:14.000,0:03:18.000
is a Freudian view, and that is that this chap --

0:03:18.000,0:03:20.000
and the same argument applies to women, by the way,

0:03:20.000,0:03:22.000
but I'll just talk about guys.

0:03:22.000,0:03:25.000
When you're a little baby, a young baby,

0:03:25.000,0:03:27.000
you had a strong sexual attraction to your mother.

0:03:27.000,0:03:29.000
This is the so-called Oedipus complex of Freud.

0:03:29.000,0:03:31.000
I'm not saying I believe this,

0:03:31.000,0:03:33.000
but this is the standard Freudian view.

0:03:33.000,0:03:36.000
And then, as you grow up, the cortex develops,

0:03:36.000,0:03:40.000
and inhibits these latent sexual urges towards your mother.

0:03:40.000,0:03:44.000
Thank God, or you would all be sexually aroused when you saw your mother.

0:03:44.000,0:03:46.000
And then what happens is,

0:03:46.000,0:03:48.000
there's a blow to your head, damaging the cortex,

0:03:48.000,0:03:52.000
allowing these latent sexual urges to emerge,

0:03:52.000,0:03:55.000
flaming to the surface, and suddenly and inexplicably

0:03:55.000,0:03:58.000
you find yourself being sexually aroused by your mother.

0:03:58.000,0:04:00.000
And you say, "My God, if this is my mom,

0:04:00.000,0:04:02.000
how come I'm being sexually turned on?

0:04:02.000,0:04:04.000
She's some other woman. She's an impostor."

0:04:04.000,0:04:08.000
It's the only interpretation that makes sense to your damaged brain.

0:04:08.000,0:04:11.000
This has never made much sense to me, this argument.

0:04:11.000,0:04:14.000
It's very ingenious, as all Freudian arguments are --

0:04:14.000,0:04:16.000
(Laughter)

0:04:16.000,0:04:21.000
-- but didn't make much sense because I have seen the same delusion,

0:04:21.000,0:04:23.000
a patient having the same delusion, about his pet poodle.

0:04:23.000,0:04:24.000
(Laughter)

0:04:24.000,0:04:29.000
He'll say, "Doctor, this is not Fifi. It looks exactly like Fifi,

0:04:29.000,0:04:31.000
but it's some other dog." Right?

0:04:31.000,0:04:33.000
Now, you try using the Freudian explanation there.

0:04:33.000,0:04:34.000
(Laughter)

0:04:34.000,0:04:38.000
You'll start talking about the latent bestiality in all humans,

0:04:38.000,0:04:41.000
or some such thing, which is quite absurd, of course.

0:04:41.000,0:04:43.000
Now, what's really going on?

0:04:43.000,0:04:45.000
So, to explain this curious disorder,

0:04:45.000,0:04:49.000
we look at the structure and functions of the normal visual pathways in the brain.

0:04:49.000,0:04:52.000
Normally, visual signals come in, into the eyeballs,

0:04:52.000,0:04:54.000
go to the visual areas in the brain.

0:04:54.000,0:04:57.000
There are, in fact, 30 areas in the back of your brain concerned with just vision,

0:04:57.000,0:05:00.000
and after processing all that, the message goes to a small structure

0:05:00.000,0:05:05.000
called the fusiform gyrus, where you perceive faces.

0:05:05.000,0:05:07.000
There are neurons there that are sensitive to faces.

0:05:07.000,0:05:10.000
You can call it the face area of the brain, right?

0:05:10.000,0:05:12.000
I talked about that earlier.

0:05:12.000,0:05:16.000
Now, when that area's damaged, you lose the ability to see faces, right?

0:05:16.000,0:05:19.000
But from that area, the message cascades

0:05:19.000,0:05:22.000
into a structure called the amygdala in the limbic system,

0:05:22.000,0:05:24.000
the emotional core of the brain,

0:05:24.000,0:05:26.000
and that structure, called the amygdala,

0:05:26.000,0:05:28.000
gauges the emotional significance of what you're looking at.

0:05:28.000,0:05:32.000
Is it prey? Is it predator? Is it mate?

0:05:32.000,0:05:34.000
Or is it something absolutely trivial, like a piece of lint,

0:05:34.000,0:05:38.000
or a piece of chalk, or a -- I don't want to point to that, but --

0:05:38.000,0:05:40.000
or a shoe, or something like that? OK?

0:05:40.000,0:05:42.000
Which you can completely ignore.

0:05:42.000,0:05:45.000
So if the amygdala is excited, and this is something important,

0:05:45.000,0:05:48.000
the messages then cascade into the autonomic nervous system.

0:05:48.000,0:05:50.000
Your heart starts beating faster.

0:05:50.000,0:05:53.000
You start sweating to dissipate the heat that you're going to

0:05:53.000,0:05:55.000
create from muscular exertion.

0:05:55.000,0:05:59.000
And that's fortunate, because we can put two electrodes on your palm

0:05:59.000,0:06:03.000
and measure the change in skin resistance produced by sweating.

0:06:03.000,0:06:05.000
So I can determine, when you're looking at something,

0:06:05.000,0:06:09.000
whether you're excited or whether you're aroused, or not, OK?

0:06:09.000,0:06:11.000
And I'll get to that in a minute.

0:06:11.000,0:06:15.000
So my idea was, when this chap looks at an object, when he looks at his --

0:06:15.000,0:06:19.000
any object for that matter, it goes to the visual areas and,

0:06:19.000,0:06:22.000
however, and it's processed in the fusiform gyrus,

0:06:22.000,0:06:25.000
and you recognize it as a pea plant, or a table,

0:06:25.000,0:06:27.000
or your mother, for that matter, OK?

0:06:27.000,0:06:30.000
And then the message cascades into the amygdala,

0:06:30.000,0:06:32.000
and then goes down the autonomic nervous system.

0:06:32.000,0:06:37.000
But maybe, in this chap, that wire that goes from the amygdala to the limbic system,

0:06:37.000,0:06:40.000
the emotional core of the brain, is cut by the accident.

0:06:40.000,0:06:42.000
So because the fusiform is intact,

0:06:42.000,0:06:45.000
the chap can still recognize his mother,

0:06:45.000,0:06:47.000
and says, "Oh yeah, this looks like my mother."

0:06:47.000,0:06:50.000
But because the wire is cut to the emotional centers,

0:06:50.000,0:06:54.000
he says, "But how come, if it's my mother, I don't experience a warmth?"

0:06:54.000,0:06:56.000
Or terror, as the case may be? Right?

0:06:56.000,0:06:57.000
(Laughter)

0:06:57.000,0:07:03.000
And therefore, he says, "How do I account for this inexplicable lack of emotions?

0:07:03.000,0:07:05.000
This can't be my mother.

0:07:05.000,0:07:07.000
It's some strange woman pretending to be my mother."

0:07:07.000,0:07:09.000
How do you test this?

0:07:09.000,0:07:11.000
Well, what you do is, if you take any one of you here, and put you in front of a screen,

0:07:11.000,0:07:14.000
and measure your galvanic skin response,

0:07:14.000,0:07:16.000
and show pictures on the screen,

0:07:16.000,0:07:19.000
I can measure how you sweat when you see an object,

0:07:19.000,0:07:22.000
like a table or an umbrella. Of course, you don't sweat.

0:07:22.000,0:07:27.000
If I show you a picture of a lion, or a tiger, or a pinup, you start sweating, right?

0:07:27.000,0:07:30.000
And, believe it or not, if I show you a picture of your mother --

0:07:30.000,0:07:32.000
I'm talking about normal people -- you start sweating.

0:07:32.000,0:07:34.000
You don't even have to be Jewish.

0:07:34.000,0:07:36.000
(Laughter)

0:07:36.000,0:07:40.000
Now, what happens if you show this patient?

0:07:40.000,0:07:44.000
You take the patient and show him pictures on the screen

0:07:44.000,0:07:46.000
and measure his galvanic skin response.

0:07:46.000,0:07:51.000
Tables and chairs and lint, nothing happens, as in normal people,

0:07:51.000,0:07:53.000
but when you show him a picture of his mother,

0:07:53.000,0:07:55.000
the galvanic skin response is flat.

0:07:55.000,0:07:57.000
There's no emotional reaction to his mother,

0:07:57.000,0:08:02.000
because that wire going from the visual areas to the emotional centers is cut.

0:08:02.000,0:08:05.000
So his vision is normal because the visual areas are normal,

0:08:05.000,0:08:08.000
his emotions are normal -- he'll laugh, he'll cry, so on and so forth --

0:08:08.000,0:08:11.000
but the wire from vision to emotions is cut

0:08:11.000,0:08:14.000
and therefore he has this delusion that his mother is an impostor.

0:08:14.000,0:08:17.000
It's a lovely example of the sort of thing we do:

0:08:17.000,0:08:21.000
take a bizarre, seemingly incomprehensible, neural psychiatric syndrome

0:08:21.000,0:08:23.000
and say that the standard Freudian view is wrong,

0:08:23.000,0:08:27.000
that, in fact, you can come up with a precise explanation

0:08:27.000,0:08:29.000
in terms of the known neural anatomy of the brain.

0:08:29.000,0:08:31.000
By the way, if this patient then goes,

0:08:31.000,0:08:36.000
and mother phones from an adjacent room -- phones him --

0:08:36.000,0:08:40.000
and he picks up the phone, and he says, "Wow, mom, how are you? Where are you?"

0:08:40.000,0:08:42.000
There's no delusion through the phone.

0:08:42.000,0:08:44.000
Then, she approaches him after an hour, he says, "Who are you?

0:08:44.000,0:08:46.000
You look just like my mother." OK?

0:08:46.000,0:08:48.000
The reason is there's a separate pathway

0:08:48.000,0:08:52.000
going from the hearing centers in the brain to the emotional centers,

0:08:52.000,0:08:54.000
and that's not been cut by the accident.

0:08:54.000,0:08:59.000
So this explains why through the phone he recognizes his mother, no problem.

0:08:59.000,0:09:02.000
When he sees her in person, he says it's an impostor.

0:09:02.000,0:09:06.000
OK, how is all this complex circuitry set up in the brain?

0:09:06.000,0:09:09.000
Is it nature, genes, or is it nurture?

0:09:09.000,0:09:11.000
And we approach this problem

0:09:11.000,0:09:15.000
by considering another curious syndrome called phantom limb.

0:09:15.000,0:09:17.000
And you all know what a phantom limb is.

0:09:17.000,0:09:20.000
When an arm is amputated, or a leg is amputated, for gangrene,

0:09:20.000,0:09:22.000
or you lose it in war -- for example, in the Iraq war,

0:09:22.000,0:09:24.000
it's now a serious problem --

0:09:24.000,0:09:28.000
you continue to vividly feel the presence of that missing arm,

0:09:28.000,0:09:31.000
and that's called a phantom arm or a phantom leg.

0:09:31.000,0:09:33.000
In fact, you can get a phantom with almost any part of the body.

0:09:33.000,0:09:36.000
Believe it or not, even with internal viscera.

0:09:36.000,0:09:40.000
I've had patients with the uterus removed -- hysterectomy --

0:09:40.000,0:09:45.000
who have a phantom uterus, including phantom menstrual cramps

0:09:45.000,0:09:47.000
at the appropriate time of the month.

0:09:47.000,0:09:49.000
And in fact, one student asked me the other day,

0:09:49.000,0:09:51.000
"Do they get phantom PMS?"

0:09:51.000,0:09:52.000
(Laughter)

0:09:52.000,0:09:56.000
A subject ripe for scientific enquiry, but we haven't pursued that.

0:09:56.000,0:09:59.000
OK, now the next question is,

0:09:59.000,0:10:02.000
what can you learn about phantom limbs by doing experiments?

0:10:02.000,0:10:04.000
One of the things we've found was,

0:10:04.000,0:10:06.000
about half the patients with phantom limbs

0:10:06.000,0:10:08.000
claim that they can move the phantom.

0:10:08.000,0:10:10.000
It'll pat his brother on the shoulder,

0:10:10.000,0:10:12.000
it'll answer the phone when it rings, it'll wave goodbye.

0:10:12.000,0:10:15.000
These are very compelling, vivid sensations.

0:10:15.000,0:10:17.000
The patient's not delusional.

0:10:17.000,0:10:19.000
He knows that the arm is not there,

0:10:19.000,0:10:22.000
but, nevertheless, it's a compelling sensory experience for the patient.

0:10:22.000,0:10:25.000
But however, about half the patients, this doesn't happen.

0:10:25.000,0:10:29.000
The phantom limb -- they'll say, "But doctor, the phantom limb is paralyzed.

0:10:29.000,0:10:32.000
It's fixed in a clenched spasm and it's excruciatingly painful.

0:10:32.000,0:10:35.000
If only I could move it, maybe the pain will be relieved."

0:10:35.000,0:10:38.000
Now, why would a phantom limb be paralyzed?

0:10:38.000,0:10:40.000
It sounds like an oxymoron.

0:10:40.000,0:10:43.000
But when we were looking at the case sheets, what we found was,

0:10:43.000,0:10:45.000
these people with the paralyzed phantom limbs,

0:10:45.000,0:10:49.000
the original arm was paralyzed because of the peripheral nerve injury.

0:10:49.000,0:10:52.000
The actual nerve supplying the arm was severed,

0:10:52.000,0:10:54.000
was cut, by say, a motorcycle accident.

0:10:54.000,0:10:57.000
So the patient had an actual arm, which is painful,

0:10:57.000,0:11:01.000
in a sling for a few months or a year, and then,

0:11:01.000,0:11:04.000
in a misguided attempt to get rid of the pain in the arm,

0:11:04.000,0:11:06.000
the surgeon amputates the arm,

0:11:06.000,0:11:10.000
and then you get a phantom arm with the same pains, right?

0:11:10.000,0:11:12.000
And this is a serious clinical problem.

0:11:12.000,0:11:14.000
Patients become depressed.

0:11:14.000,0:11:16.000
Some of them are driven to suicide, OK?

0:11:16.000,0:11:18.000
So, how do you treat this syndrome?

0:11:18.000,0:11:20.000
Now, why do you get a paralyzed phantom limb?

0:11:20.000,0:11:24.000
When I looked at the case sheet, I found that they had an actual arm,

0:11:24.000,0:11:27.000
and the nerves supplying the arm had been cut,

0:11:27.000,0:11:30.000
and the actual arm had been paralyzed,

0:11:30.000,0:11:34.000
and lying in a sling for several months before the amputation,

0:11:34.000,0:11:40.000
and this pain then gets carried over into the phantom itself.

0:11:40.000,0:11:42.000
Why does this happen?

0:11:42.000,0:11:44.000
When the arm was intact, but paralyzed,

0:11:44.000,0:11:47.000
the brain sends commands to the arm, the front of the brain, saying, "Move,"

0:11:47.000,0:11:49.000
but it's getting visual feedback saying, "No."

0:11:49.000,0:11:53.000
Move. No. Move. No. Move. No.

0:11:53.000,0:11:56.000
And this gets wired into the circuitry of the brain,

0:11:56.000,0:11:59.000
and we call this learned paralysis, OK?

0:11:59.000,0:12:03.000
The brain learns, because of this Hebbian, associative link,

0:12:03.000,0:12:06.000
that the mere command to move the arm

0:12:06.000,0:12:08.000
creates a sensation of a paralyzed arm.

0:12:08.000,0:12:10.000
And then, when you've amputated the arm,

0:12:10.000,0:12:14.000
this learned paralysis carries over into your body image

0:12:14.000,0:12:17.000
and into your phantom, OK?

0:12:17.000,0:12:19.000
Now, how do you help these patients?

0:12:19.000,0:12:21.000
How do you unlearn the learned paralysis,

0:12:21.000,0:12:25.000
so you can relieve him of this excruciating, clenching spasm

0:12:25.000,0:12:27.000
of the phantom arm?

0:12:27.000,0:12:32.000
Well, we said, what if you now send the command to the phantom,

0:12:32.000,0:12:36.000
but give him visual feedback that it's obeying his command, right?

0:12:36.000,0:12:39.000
Maybe you can relieve the phantom pain, the phantom cramp.

0:12:39.000,0:12:41.000
How do you do that? Well, virtual reality.

0:12:41.000,0:12:43.000
But that costs millions of dollars.

0:12:43.000,0:12:46.000
So, I hit on a way of doing this for three dollars,

0:12:46.000,0:12:48.000
but don't tell my funding agencies.

0:12:48.000,0:12:49.000
(Laughter)

0:12:49.000,0:12:53.000
OK? What you do is you create what I call a mirror box.

0:12:53.000,0:12:55.000
You have a cardboard box with a mirror in the middle,

0:12:55.000,0:12:59.000
and then you put the phantom -- so my first patient, Derek, came in.

0:12:59.000,0:13:02.000
He had his arm amputated 10 years ago.

0:13:02.000,0:13:05.000
He had a brachial avulsion, so the nerves were cut

0:13:05.000,0:13:09.000
and the arm was paralyzed, lying in a sling for a year, and then the arm was amputated.

0:13:09.000,0:13:11.000
He had a phantom arm, excruciatingly painful, and he couldn't move it.

0:13:11.000,0:13:13.000
It was a paralyzed phantom arm.

0:13:13.000,0:13:17.000
So he came there, and I gave him a mirror like that, in a box,

0:13:17.000,0:13:20.000
which I call a mirror box, right?

0:13:20.000,0:13:23.000
And the patient puts his phantom left arm,

0:13:23.000,0:13:25.000
which is clenched and in spasm, on the left side of the mirror,

0:13:25.000,0:13:27.000
and the normal hand on the right side of the mirror,

0:13:27.000,0:13:31.000
and makes the same posture, the clenched posture,

0:13:31.000,0:13:34.000
and looks inside the mirror. And what does he experience?

0:13:34.000,0:13:37.000
He looks at the phantom being resurrected,

0:13:37.000,0:13:41.000
because he's looking at the reflection of the normal arm in the mirror,

0:13:41.000,0:13:43.000
and it looks like this phantom has been resurrected.

0:13:43.000,0:13:46.000
"Now," I said, "now, look, wiggle your phantom --

0:13:46.000,0:13:50.000
your real fingers, or move your real fingers while looking in the mirror."

0:13:50.000,0:13:54.000
He's going to get the visual impression that the phantom is moving, right?

0:13:54.000,0:13:56.000
That's obvious, but the astonishing thing is,

0:13:56.000,0:13:59.000
the patient then says, "Oh my God, my phantom is moving again,

0:13:59.000,0:14:01.000
and the pain, the clenching spasm, is relieved."

0:14:01.000,0:14:04.000
And remember, my first patient who came in --

0:14:04.000,0:14:05.000
(Applause)

0:14:05.000,0:14:09.000
-- thank you. (Applause)

0:14:09.000,0:14:12.000
My first patient came in, and he looked in the mirror,

0:14:12.000,0:14:15.000
and I said, "Look at your reflection of your phantom."

0:14:15.000,0:14:17.000
And he started giggling, he says, "I can see my phantom."

0:14:17.000,0:14:19.000
But he's not stupid. He knows it's not real.

0:14:19.000,0:14:21.000
He knows it's a mirror reflection,

0:14:21.000,0:14:23.000
but it's a vivid sensory experience.

0:14:23.000,0:14:26.000
Now, I said, "Move your normal hand and phantom."

0:14:26.000,0:14:28.000
He said, "Oh, I can't move my phantom. You know that. It's painful."

0:14:28.000,0:14:30.000
I said, "Move your normal hand."

0:14:30.000,0:14:32.000
And he says, "Oh my God, my phantom is moving again. I don't believe this!

0:14:32.000,0:14:35.000
And my pain is being relieved." OK?

0:14:35.000,0:14:36.000
And then I said, "Close your eyes."

0:14:36.000,0:14:38.000
He closes his eyes.

0:14:38.000,0:14:39.000
"And move your normal hand."

0:14:39.000,0:14:40.000
"Oh, nothing. It's clenched again."

0:14:40.000,0:14:42.000
"OK, open your eyes."

0:14:42.000,0:14:43.000
"Oh my God, oh my God, it's moving again!"

0:14:43.000,0:14:45.000
So, he was like a kid in a candy store.

0:14:45.000,0:14:50.000
So, I said, OK, this proves my theory about learned paralysis

0:14:50.000,0:14:52.000
and the critical role of visual input,

0:14:52.000,0:14:54.000
but I'm not going to get a Nobel Prize

0:14:54.000,0:14:56.000
for getting somebody to move his phantom limb.

0:14:56.000,0:14:57.000
(Laughter)

0:14:57.000,0:14:58.000
(Applause)

0:14:58.000,0:15:01.000
It's a completely useless ability, if you think about it.

0:15:01.000,0:15:02.000
(Laughter)

0:15:02.000,0:15:06.000
But then I started realizing, maybe other kinds of paralysis

0:15:06.000,0:15:11.000
that you see in neurology, like stroke, focal dystonias --

0:15:11.000,0:15:13.000
there may be a learned component to this,

0:15:13.000,0:15:16.000
which you can overcome with the simple device of using a mirror.

0:15:16.000,0:15:18.000
So, I said, "Look, Derek" --

0:15:18.000,0:15:21.000
well, first of all, the guy can't just go around carrying a mirror to alleviate his pain --

0:15:21.000,0:15:25.000
I said, "Look, Derek, take it home and practice with it for a week or two.

0:15:25.000,0:15:27.000
Maybe, after a period of practice,

0:15:27.000,0:15:29.000
you can dispense with the mirror, unlearn the paralysis,

0:15:29.000,0:15:31.000
and start moving your paralyzed arm,

0:15:31.000,0:15:33.000
and then, relieve yourself of pain."

0:15:33.000,0:15:35.000
So he said OK, and he took it home.

0:15:35.000,0:15:37.000
I said, "Look, it's, after all, two dollars. Take it home."

0:15:37.000,0:15:40.000
So, he took it home, and after two weeks, he phones me,

0:15:40.000,0:15:42.000
and he said, "Doctor, you're not going to believe this."

0:15:42.000,0:15:43.000
I said, "What?"

0:15:43.000,0:15:45.000
He said, "It's gone."

0:15:45.000,0:15:46.000
I said, "What's gone?"

0:15:46.000,0:15:48.000
I thought maybe the mirror box was gone.

0:15:48.000,0:15:49.000
(Laughter)

0:15:49.000,0:15:52.000
He said, "No, no, no, you know this phantom I've had for the last 10 years?

0:15:52.000,0:15:54.000
It's disappeared."

0:15:54.000,0:15:56.000
And I said -- I got worried, I said, my God,

0:15:56.000,0:15:58.000
I mean I've changed this guy's body image,

0:15:58.000,0:16:01.000
what about human subjects, ethics and all of that?

0:16:01.000,0:16:03.000
And I said, "Derek, does this bother you?"

0:16:03.000,0:16:06.000
He said, "No, last three days, I've not had a phantom arm

0:16:06.000,0:16:09.000
and therefore no phantom elbow pain, no clenching,

0:16:09.000,0:16:12.000
no phantom forearm pain, all those pains are gone away.

0:16:12.000,0:16:16.000
But the problem is I still have my phantom fingers dangling from the shoulder,

0:16:16.000,0:16:18.000
and your box doesn't reach."

0:16:18.000,0:16:19.000
(Laughter)

0:16:19.000,0:16:22.000
"So, can you change the design and put it on my forehead,

0:16:22.000,0:16:25.000
so I can, you know, do this and eliminate my phantom fingers?"

0:16:25.000,0:16:27.000
He thought I was some kind of magician.

0:16:27.000,0:16:28.000
Now, why does this happen?

0:16:28.000,0:16:31.000
It's because the brain is faced with tremendous sensory conflict.

0:16:31.000,0:16:34.000
It's getting messages from vision saying the phantom is back.

0:16:34.000,0:16:36.000
On the other hand, there's no proprioception,

0:16:36.000,0:16:40.000
muscle signals saying that there is no arm, right?

0:16:40.000,0:16:42.000
And your motor command saying there is an arm,

0:16:42.000,0:16:45.000
and, because of this conflict, the brain says, to hell with it,

0:16:45.000,0:16:48.000
there is no phantom, there is no arm, right?

0:16:48.000,0:16:50.000
It goes into a sort of denial -- it gates the signals.

0:16:50.000,0:16:54.000
And when the arm disappears, the bonus is, the pain disappears

0:16:54.000,0:16:58.000
because you can't have disembodied pain floating out there, in space.

0:16:58.000,0:17:00.000
So, that's the bonus.

0:17:00.000,0:17:02.000
Now, this technique has been tried on dozens of patients

0:17:02.000,0:17:04.000
by other groups in Helsinki,

0:17:04.000,0:17:07.000
so it may prove to be valuable as a treatment for phantom pain,

0:17:07.000,0:17:09.000
and indeed, people have tried it for stroke rehabilitation.

0:17:09.000,0:17:12.000
Stroke you normally think of as damage to the fibers,

0:17:12.000,0:17:14.000
nothing you can do about it.

0:17:14.000,0:17:19.000
But, it turns out some component of stroke paralysis is also learned paralysis,

0:17:19.000,0:17:22.000
and maybe that component can be overcome using mirrors.

0:17:22.000,0:17:24.000
This has also gone through clinical trials,

0:17:24.000,0:17:26.000
helping lots and lots of patients.

0:17:26.000,0:17:30.000
OK, let me switch gears now to the third part of my talk,

0:17:30.000,0:17:34.000
which is about another curious phenomenon called synesthesia.

0:17:34.000,0:17:37.000
This was discovered by Francis Galton in the nineteenth century.

0:17:37.000,0:17:39.000
He was a cousin of Charles Darwin.

0:17:39.000,0:17:41.000
He pointed out that certain people in the population,

0:17:41.000,0:17:45.000
who are otherwise completely normal, had the following peculiarity:

0:17:45.000,0:17:48.000
every time they see a number, it's colored.

0:17:48.000,0:17:52.000
Five is blue, seven is yellow, eight is chartreuse,

0:17:52.000,0:17:54.000
nine is indigo, OK?

0:17:54.000,0:17:57.000
Bear in mind, these people are completely normal in other respects.

0:17:57.000,0:18:00.000
Or C sharp -- sometimes, tones evoke color.

0:18:00.000,0:18:03.000
C sharp is blue, F sharp is green,

0:18:03.000,0:18:06.000
another tone might be yellow, right?

0:18:06.000,0:18:08.000
Why does this happen?

0:18:08.000,0:18:10.000
This is called synesthesia. Galton called it synesthesia,

0:18:10.000,0:18:12.000
a mingling of the senses.

0:18:12.000,0:18:14.000
In us, all the senses are distinct.

0:18:14.000,0:18:16.000
These people muddle up their senses.

0:18:16.000,0:18:17.000
Why does this happen?

0:18:17.000,0:18:19.000
One of the two aspects of this problem are very intriguing.

0:18:19.000,0:18:21.000
Synesthesia runs in families,

0:18:21.000,0:18:24.000
so Galton said this is a hereditary basis, a genetic basis.

0:18:24.000,0:18:28.000
Secondly, synesthesia is about -- and this is what gets me to my point

0:18:28.000,0:18:31.000
about the main theme of this lecture, which is about creativity --

0:18:31.000,0:18:36.000
synesthesia is eight times more common among artists, poets, novelists

0:18:36.000,0:18:39.000
and other creative people than in the general population.

0:18:39.000,0:18:40.000
Why would that be?

0:18:40.000,0:18:42.000
I'm going to answer that question.

0:18:42.000,0:18:44.000
It's never been answered before.

0:18:44.000,0:18:45.000
OK, what is synesthesia? What causes it?

0:18:45.000,0:18:46.000
Well, there are many theories.

0:18:46.000,0:18:48.000
One theory is they're just crazy.

0:18:48.000,0:18:51.000
Now, that's not really a scientific theory, so we can forget about it.

0:18:51.000,0:18:55.000
Another theory is they are acid junkies and potheads, right?

0:18:55.000,0:18:57.000
Now, there may be some truth to this,

0:18:57.000,0:18:59.000
because it's much more common here in the Bay Area than in San Diego.

0:18:59.000,0:19:00.000
(Laughter)

0:19:00.000,0:19:03.000
OK. Now, the third theory is that --

0:19:03.000,0:19:08.000
well, let's ask ourselves what's really going on in synesthesia. All right?

0:19:08.000,0:19:11.000
So, we found that the color area and the number area

0:19:11.000,0:19:14.000
are right next to each other in the brain, in the fusiform gyrus.

0:19:14.000,0:19:16.000
So we said, there's some accidental cross wiring

0:19:16.000,0:19:19.000
between color and numbers in the brain.

0:19:19.000,0:19:22.000
So, every time you see a number, you see a corresponding color,

0:19:22.000,0:19:24.000
and that's why you get synesthesia.

0:19:24.000,0:19:26.000
Now remember -- why does this happen?

0:19:26.000,0:19:28.000
Why would there be crossed wires in some people?

0:19:28.000,0:19:30.000
Remember I said it runs in families?

0:19:30.000,0:19:32.000
That gives you the clue.

0:19:32.000,0:19:34.000
And that is, there is an abnormal gene,

0:19:34.000,0:19:37.000
a mutation in the gene that causes this abnormal cross wiring.

0:19:37.000,0:19:39.000
In all of us, it turns out

0:19:39.000,0:19:43.000
we are born with everything wired to everything else.

0:19:43.000,0:19:46.000
So, every brain region is wired to every other region,

0:19:46.000,0:19:48.000
and these are trimmed down to create

0:19:48.000,0:19:51.000
the characteristic modular architecture of the adult brain.

0:19:51.000,0:19:53.000
So, if there's a gene causing this trimming

0:19:53.000,0:19:55.000
and if that gene mutates,

0:19:55.000,0:19:58.000
then you get deficient trimming between adjacent brain areas.

0:19:58.000,0:20:01.000
And if it's between number and color, you get number-color synesthesia.

0:20:01.000,0:20:04.000
If it's between tone and color, you get tone-color synesthesia.

0:20:04.000,0:20:06.000
So far, so good.

0:20:06.000,0:20:08.000
Now, what if this gene is expressed everywhere in the brain,

0:20:08.000,0:20:09.000
so everything is cross-connected?

0:20:09.000,0:20:15.000
Well, think about what artists, novelists and poets have in common,

0:20:15.000,0:20:18.000
the ability to engage in metaphorical thinking,

0:20:18.000,0:20:20.000
linking seemingly unrelated ideas,

0:20:20.000,0:20:23.000
such as, "It is the east, and Juliet is the Sun."

0:20:23.000,0:20:25.000
Well, you don't say, Juliet is the sun,

0:20:25.000,0:20:27.000
does that mean she's a glowing ball of fire?

0:20:27.000,0:20:30.000
I mean, schizophrenics do that, but it's a different story, right?

0:20:30.000,0:20:33.000
Normal people say, she's warm like the sun,

0:20:33.000,0:20:35.000
she's radiant like the sun, she's nurturing like the sun.

0:20:35.000,0:20:37.000
Instantly, you've found the links.

0:20:37.000,0:20:40.000
Now, if you assume that this greater cross wiring

0:20:40.000,0:20:43.000
and concepts are also in different parts of the brain,

0:20:43.000,0:20:46.000
then it's going to create a greater propensity

0:20:46.000,0:20:49.000
towards metaphorical thinking and creativity

0:20:49.000,0:20:51.000
in people with synesthesia.

0:20:51.000,0:20:54.000
And, hence, the eight times more common incidence of synesthesia

0:20:54.000,0:20:56.000
among poets, artists and novelists.

0:20:56.000,0:20:59.000
OK, it's a very phrenological view of synesthesia.

0:20:59.000,0:21:01.000
The last demonstration -- can I take one minute?

0:21:01.000,0:21:03.000
(Applause)

0:21:03.000,0:21:08.000
OK. I'm going to show you that you're all synesthetes, but you're in denial about it.

0:21:08.000,0:21:12.000
Here's what I call Martian alphabet. Just like your alphabet,

0:21:12.000,0:21:15.000
A is A, B is B, C is C.

0:21:15.000,0:21:18.000
Different shapes for different phonemes, right?

0:21:18.000,0:21:20.000
Here, you've got Martian alphabet.

0:21:20.000,0:21:22.000
One of them is Kiki, one of them is Bouba.

0:21:22.000,0:21:24.000
Which one is Kiki and which one is Bouba?

0:21:24.000,0:21:26.000
How many of you think that's Kiki and that's Bouba? Raise your hands.

0:21:26.000,0:21:28.000
Well, it's one or two mutants.

0:21:28.000,0:21:29.000
(Laughter)

0:21:29.000,0:21:31.000
How many of you think that's Bouba, that's Kiki? Raise your hands.

0:21:31.000,0:21:33.000
Ninety-nine percent of you.

0:21:33.000,0:21:35.000
Now, none of you is a Martian. How did you do that?

0:21:35.000,0:21:40.000
It's because you're all doing a cross-model synesthetic abstraction,

0:21:40.000,0:21:44.000
meaning you're saying that that sharp inflection -- ki-ki,

0:21:44.000,0:21:49.000
in your auditory cortex, the hair cells being excited -- Kiki,

0:21:49.000,0:21:52.000
mimics the visual inflection, sudden inflection of that jagged shape.

0:21:52.000,0:21:55.000
Now, this is very important, because what it's telling you

0:21:55.000,0:21:57.000
is your brain is engaging in a primitive --

0:21:57.000,0:21:59.000
it's just -- it looks like a silly illusion,

0:21:59.000,0:22:03.000
but these photons in your eye are doing this shape,

0:22:03.000,0:22:06.000
and hair cells in your ear are exciting the auditory pattern,

0:22:06.000,0:22:11.000
but the brain is able to extract the common denominator.

0:22:11.000,0:22:13.000
It's a primitive form of abstraction,

0:22:13.000,0:22:18.000
and we now know this happens in the fusiform gyrus of the brain,

0:22:18.000,0:22:19.000
because when that's damaged,

0:22:19.000,0:22:23.000
these people lose the ability to engage in Bouba Kiki,

0:22:23.000,0:22:25.000
but they also lose the ability to engage in metaphor.

0:22:25.000,0:22:29.000
If you ask this guy, what -- "all that glitters is not gold,"

0:22:29.000,0:22:31.000
what does that mean?"

0:22:31.000,0:22:33.000
The patient says, "Well, if it's metallic and shiny, it doesn't mean it's gold.

0:22:33.000,0:22:36.000
You have to measure its specific gravity, OK?"

0:22:36.000,0:22:39.000
So, they completely miss the metaphorical meaning.

0:22:39.000,0:22:42.000
So, this area is about eight times the size in higher --

0:22:42.000,0:22:45.000
especially in humans -- as in lower primates.

0:22:45.000,0:22:48.000
Something very interesting is going on here in the angular gyrus,

0:22:48.000,0:22:51.000
because it's the crossroads between hearing, vision and touch,

0:22:51.000,0:22:55.000
and it became enormous in humans. And something very interesting is going on.

0:22:55.000,0:22:58.000
And I think it's a basis of many uniquely human abilities

0:22:58.000,0:23:01.000
like abstraction, metaphor and creativity.

0:23:01.000,0:23:04.000
All of these questions that philosophers have been studying for millennia,

0:23:04.000,0:23:08.000
we scientists can begin to explore by doing brain imaging,

0:23:08.000,0:23:10.000
and by studying patients and asking the right questions.

0:23:10.000,0:23:12.000
Thank you.

0:23:12.000,0:23:13.000
(Applause)

0:23:13.000,0:23:14.000
Sorry about that.

0:23:14.000,0:23:15.000
(Laughter)