0:00:00.825,0:00:02.785
We see with the eyes,

0:00:02.809,0:00:05.254
but we see with the brain as well.

0:00:06.000,0:00:09.839
And seeing with the brain[br]is often called imagination.

0:00:10.982,0:00:15.165
And we are familiar with[br]the landscapes of our own imagination,

0:00:15.189,0:00:16.559
our inscapes.

0:00:16.583,0:00:18.583
We've lived with them all our lives.

0:00:19.306,0:00:22.799
But there are also hallucinations as well.

0:00:23.332,0:00:25.976
And hallucinations[br]are completely different.

0:00:26.000,0:00:28.110
They don't seem to be of our creation.

0:00:28.134,0:00:30.174
They don't seem to be under our control.

0:00:30.198,0:00:34.488
They seem to come from the outside[br]and to mimic perception.

0:00:34.960,0:00:39.031
So I am going to be talking[br]about hallucinations

0:00:39.055,0:00:42.166
and a particular sort[br]of visual hallucination,

0:00:43.658,0:00:46.705
which I see among my patients.

0:00:48.594,0:00:54.006
A few months ago, I got a phone call[br]from a nursing home where I work.

0:00:54.496,0:00:59.229
They told me that one of their residents,[br]an old lady in her 90s,

0:00:59.253,0:01:00.743
was seeing things,

0:01:01.602,0:01:04.288
and they wondered if she'd gone bonkers

0:01:04.312,0:01:05.858
or, because she was an old lady,

0:01:05.882,0:01:09.170
whether she'd had a stroke,[br]or whether she had Alzheimer's.

0:01:09.194,0:01:13.375
And so they asked me[br]if I would come and see Rosalie,

0:01:14.478,0:01:15.700
the old lady.

0:01:16.327,0:01:17.976
I went in to see her.

0:01:18.358,0:01:22.948
It was evident straightaway[br]that she was perfectly sane

0:01:22.972,0:01:26.764
and lucid and of good intelligence,

0:01:26.788,0:01:30.153
but she'd been very startled[br]and very bewildered,

0:01:30.177,0:01:32.187
because she'd been seeing things.

0:01:33.672,0:01:37.976
And she told me --[br]the nurses hadn't mentioned this --

0:01:38.000,0:01:40.276
that she was blind,

0:01:40.300,0:01:45.121
that she had been completely blind[br]from macular degeneration for five years.

0:01:45.145,0:01:48.695
But now, for the last few days,[br]she'd been seeing things.

0:01:48.719,0:01:50.716
So I said, "What sort of things?"

0:01:50.740,0:01:54.457
And she said, "People in Eastern dress,

0:01:54.481,0:01:57.475
in drapes, walking up and down stairs.

0:01:58.290,0:02:01.449
A man who turns towards me and smiles,

0:02:01.473,0:02:04.812
but he has huge teeth[br]on the one side of his mouth.

0:02:05.510,0:02:06.845
Animals, too.

0:02:07.597,0:02:10.605
I see a white building.[br]It's snowing, a soft snow.

0:02:10.629,0:02:14.614
I see this horse with a harness,[br]dragging the snow away.

0:02:15.527,0:02:18.802
Then, one night, the scene changes.

0:02:18.826,0:02:21.380
I see cats and dogs walking towards me.

0:02:21.404,0:02:24.038
They come to a certain point[br]and then stop.

0:02:24.570,0:02:26.133
Then it changes again.

0:02:26.157,0:02:29.279
I see a lot of children.[br]They're walking up and down stairs.

0:02:29.303,0:02:32.240
They wear bright colors, rose and blue,

0:02:32.264,0:02:33.854
like Eastern dress."

0:02:34.857,0:02:38.434
Sometimes, she said,[br]before the people come on,

0:02:38.458,0:02:41.976
she may hallucinate[br]pink and blue squares on the floor,

0:02:42.000,0:02:43.888
which seem to go up to the ceiling.

0:02:44.856,0:02:49.454
I said, "Is this like a dream?"

0:02:49.478,0:02:52.837
And she said, "No, it's not[br]like a dream. It's like a movie."

0:02:52.861,0:02:55.500
She said, "It's got color.[br]It's got motion.

0:02:55.524,0:02:58.976
But it's completely silent,[br]like a silent movie."

0:02:59.000,0:03:01.157
And she said that[br]it's a rather boring movie.

0:03:01.181,0:03:03.856
She said, "All these people[br]with Eastern dress,

0:03:03.880,0:03:08.526
walking up and down,[br]very repetitive, very limited."

0:03:08.550,0:03:09.952
(Laughter)

0:03:09.976,0:03:12.747
And she has a sense of humor.

0:03:12.771,0:03:16.073
She knew it was a hallucination,[br]but she was frightened.

0:03:16.097,0:03:17.461
She had lived 95 years,

0:03:17.485,0:03:19.762
and she'd never had[br]a hallucination before.

0:03:20.247,0:03:25.303
She said that the hallucinations were[br]unrelated to anything she was thinking

0:03:25.327,0:03:27.342
or feeling or doing,

0:03:27.366,0:03:30.976
that they seemed to come on[br]by themselves, or disappear.

0:03:31.437,0:03:33.936
She had no control over them.

0:03:33.960,0:03:37.478
She said she didn't recognize[br]any of the people or places

0:03:37.502,0:03:39.248
in the hallucinations,

0:03:39.272,0:03:41.521
and none of the people or the animals --

0:03:41.545,0:03:44.350
well, they all seemed oblivious of her.

0:03:45.223,0:03:47.240
And she didn't know what was going on.

0:03:47.264,0:03:51.196
She wondered if she was going mad[br]or losing her mind.

0:03:51.220,0:03:53.729
Well, I examined her carefully.

0:03:53.753,0:03:55.672
She was a bright old lady,

0:03:55.696,0:03:57.507
perfectly sane.

0:03:57.531,0:03:59.441
She had no medical problems.

0:03:59.465,0:04:03.061
She wasn't on any medications[br]which could produce hallucinations.

0:04:03.085,0:04:04.566
But she was blind.

0:04:05.657,0:04:09.460
And I then said to her,[br]"I think I know what you have."

0:04:09.484,0:04:12.976
I said, "There is a special form[br]of visual hallucination

0:04:13.000,0:04:17.077
which may go with deteriorating[br]vision or blindness.

0:04:17.640,0:04:19.857
This was originally described," I said,

0:04:19.881,0:04:22.103
"right back in the 18th century,

0:04:22.127,0:04:25.082
by a man called Charles Bonnet.

0:04:25.106,0:04:27.797
And you have Charles Bonnet syndrome.

0:04:27.821,0:04:31.437
There's nothing wrong with your brain.[br]There's nothing wrong with your mind.

0:04:31.461,0:04:33.493
You have Charles Bonnet syndrome."

0:04:33.517,0:04:36.342
And she was very relieved at this,

0:04:36.366,0:04:39.112
that there was nothing[br]seriously the matter,

0:04:39.136,0:04:42.603
and also rather curious.

0:04:42.627,0:04:45.610
She said, "Who is this Charles Bonnet?"

0:04:45.634,0:04:47.607
She said, "Did he have them himself?"

0:04:48.107,0:04:51.587
And she said, "Tell all the nurses

0:04:51.611,0:04:53.579
that I have Charles Bonnet syndrome."

0:04:53.603,0:04:55.103
(Laughter)

0:04:55.127,0:04:59.164
"I'm not crazy. I'm not demented.[br]I have Charles Bonnet syndrome."

0:05:00.000,0:05:02.101
Well, so, I did tell the nurses.

0:05:02.125,0:05:04.976
Now this, for me, is a common situation.

0:05:05.000,0:05:07.746
I work in old-age homes, largely.

0:05:07.770,0:05:09.937
I see a lot of elderly people

0:05:09.961,0:05:12.918
who are hearing impaired[br]or visually impaired.

0:05:12.942,0:05:15.594
About 10 percent[br]of the hearing-impaired people

0:05:15.618,0:05:18.188
get musical hallucinations.

0:05:18.212,0:05:21.193
And about 10 percent[br]of the visually impaired people

0:05:21.217,0:05:23.114
get visual hallucinations.

0:05:23.138,0:05:25.399
You don't have to be completely blind,

0:05:25.423,0:05:27.693
only sufficiently impaired.

0:05:27.717,0:05:31.604
Now, with the original description[br]in the 18th century,

0:05:31.628,0:05:33.443
Charles Bonnet did not have them.

0:05:33.467,0:05:36.209
His grandfather had these hallucinations.

0:05:36.233,0:05:39.573
His grandfather was[br]a magistrate, an elderly man.

0:05:39.597,0:05:41.830
He'd had cataract surgery.

0:05:41.854,0:05:44.105
His vision was pretty poor.

0:05:44.129,0:05:49.294
And in 1759, he described to his grandson

0:05:49.318,0:05:51.635
various things he was seeing.

0:05:51.659,0:05:55.107
The first thing he said was[br]he saw a handkerchief in midair.

0:05:55.131,0:05:58.976
It was a large blue handkerchief[br]with four orange circles.

0:05:59.456,0:06:01.827
And he knew it was a hallucination.

0:06:01.851,0:06:04.214
You don't have handkerchiefs in midair.

0:06:04.238,0:06:07.525
And then he saw a big wheel in midair.

0:06:08.327,0:06:13.277
But sometimes he wasn't sure[br]whether he was hallucinating or not,

0:06:13.301,0:06:16.976
because the hallucinations would fit[br]in the context of the visions.

0:06:17.000,0:06:20.821
So on one occasion, when[br]his granddaughters were visiting them,

0:06:20.845,0:06:23.934
he said, "And who are these[br]handsome young men with you?"

0:06:24.880,0:06:29.685
And they said, "Alas, Grandpapa,[br]there are no handsome young men."

0:06:29.709,0:06:32.102
And then the handsome[br]young men disappeared.

0:06:33.459,0:06:35.976
It's typical of these hallucinations

0:06:36.000,0:06:38.976
that they may come in a flash[br]and disappear in a flash.

0:06:39.000,0:06:41.568
They don't usually fade in and out.

0:06:41.592,0:06:44.935
They are rather sudden,[br]and they change suddenly.

0:06:44.959,0:06:46.976
Charles Lullin, the grandfather,

0:06:47.000,0:06:49.976
saw hundreds of different figures,

0:06:50.000,0:06:52.611
different landscapes of all sorts.

0:06:52.635,0:06:56.448
On one occasion, he saw a man[br]in a bathrobe smoking a pipe

0:06:56.472,0:06:58.544
and realized it was himself.

0:06:59.306,0:07:01.976
That was the only figure he recognized.

0:07:02.694,0:07:05.976
On one occasion, when he was walking[br]in the streets of Paris,

0:07:06.000,0:07:09.039
he saw -- this was real -- a scaffolding.

0:07:09.063,0:07:12.577
But when he got back home,[br]he saw a miniature of the scaffolding,

0:07:12.601,0:07:14.327
six inches high,

0:07:14.351,0:07:16.119
on his study table.

0:07:16.143,0:07:20.975
This repetition of perception[br]is sometimes called "palinopsia."

0:07:22.445,0:07:26.372
With him and with Rosalie,

0:07:26.396,0:07:27.976
what seems to be going on --

0:07:28.000,0:07:30.148
and Rosalie said, "What's going on?" --

0:07:30.172,0:07:32.976
and I said that as you lose vision,

0:07:33.000,0:07:36.048
as the visual parts of the brain[br]are no longer getting any input,

0:07:36.072,0:07:39.154
they become hyperactive and excitable,

0:07:39.178,0:07:41.879
and they start to fire spontaneously.

0:07:41.903,0:07:44.053
And you start to see things.

0:07:44.077,0:07:48.007
The things you see[br]can be very complicated indeed.

0:07:48.031,0:07:53.496
With another patient of mine[br]who also had some vision,

0:07:54.829,0:07:57.365
the visions she had could be disturbing.

0:07:57.389,0:08:02.976
On one occasion, she said she saw[br]a man in a striped shirt in a restaurant.

0:08:03.000,0:08:04.296
And he turned round,

0:08:04.320,0:08:08.423
and then he divided into[br]six figures in striped shirts,

0:08:08.447,0:08:10.857
who started walking towards her.

0:08:10.881,0:08:14.290
And then the six figures came[br]together, like a concertina.

0:08:14.314,0:08:16.036
Once, when she was driving,

0:08:16.060,0:08:17.976
or rather, her husband was driving,

0:08:18.000,0:08:20.292
the road divided into four

0:08:20.316,0:08:24.192
and she felt herself going[br]simultaneously up four roads.

0:08:24.859,0:08:29.650
She had very mobile[br]hallucinations as well.

0:08:29.674,0:08:31.844
A lot of them had to do with a car.

0:08:31.868,0:08:36.698
Sometimes she would see a teenage boy[br]sitting on the hood of the car.

0:08:36.722,0:08:38.219
He was very tenacious,

0:08:38.243,0:08:41.543
and he moved rather gracefully[br]when the car turned.

0:08:41.567,0:08:43.976
And then when they came to a stop,

0:08:44.000,0:08:47.537
the boy would do a sudden vertical[br]takeoff, 100 foot in the air,

0:08:47.561,0:08:48.973
and then disappear.

0:08:50.377,0:08:54.976
Another patient of mine[br]had a different sort of hallucination.

0:08:55.000,0:08:57.887
This was a woman who didn't have[br]trouble with her eyes

0:08:57.911,0:08:59.976
but the visual parts of her brain,

0:09:00.000,0:09:03.658
a little tumor in the occipital cortex.

0:09:03.682,0:09:07.463
And, above all, she would see cartoons.

0:09:08.288,0:09:12.795
These cartoons would be transparent

0:09:12.819,0:09:16.782
and would cover[br]half the visual field, like a screen.

0:09:16.806,0:09:21.585
And especially, she saw[br]cartoons of Kermit the Frog.

0:09:21.609,0:09:23.061
(Laughter)

0:09:23.085,0:09:27.107
Now, I don't watch Sesame Street,

0:09:27.131,0:09:29.586
but she made a point of saying,

0:09:29.610,0:09:32.976
"Why Kermit?" she said,[br]"Kermit the Frog means nothing to me."

0:09:33.000,0:09:38.111
You know, I was wondering about[br]Freudian determinants: Why Kermit?

0:09:38.135,0:09:40.500
"Kermit the Frog means nothing to me."

0:09:40.524,0:09:42.706
She didn't mind the cartoons too much.

0:09:42.730,0:09:44.469
But what did disturb her was,

0:09:44.493,0:09:48.912
she got very persistent images[br]or hallucinations of faces,

0:09:48.936,0:09:52.423
and as with Rosalie,[br]the faces were often deformed,

0:09:52.447,0:09:55.585
with very large teeth or very large eyes.

0:09:56.000,0:09:58.254
And these frightened her.

0:09:59.262,0:10:03.040
Well, what is going on with these people?

0:10:03.064,0:10:06.678
As a physician, I have to try[br]and define what's going on

0:10:06.702,0:10:08.408
and to reassure people,

0:10:08.432,0:10:11.976
especially to reassure them[br]that they're not going insane.

0:10:12.395,0:10:15.244
Something like 10 percent, as I said,

0:10:15.268,0:10:18.221
of visually impaired people get these.

0:10:18.245,0:10:21.976
But no more than one percent[br]of the people acknowledge them,

0:10:22.000,0:10:25.356
because they are afraid[br]they will be seen as insane or something.

0:10:25.380,0:10:27.828
And if they do mention them[br]to their own doctors,

0:10:27.852,0:10:29.707
they may be misdiagnosed.

0:10:30.080,0:10:33.596
In particular, the notion is that if you[br]see things or hear things,

0:10:33.620,0:10:34.846
you're going mad.

0:10:34.870,0:10:37.895
But the psychotic hallucinations[br]are quite different.

0:10:37.919,0:10:41.118
Psychotic hallucinations,[br]whether they are visual or vocal,

0:10:41.142,0:10:42.318
they address you.

0:10:42.342,0:10:47.052
They accuse you, they seduce you,[br]they humiliate you, they jeer at you.

0:10:47.960,0:10:49.657
You interact with them.

0:10:50.086,0:10:53.614
There is none of this quality[br]of being addressed

0:10:53.638,0:10:56.099
with these Charles Bonnet hallucinations.

0:10:56.123,0:11:00.726
There is a film. You're seeing a film[br]which has nothing to do with you,

0:11:00.750,0:11:03.292
or that's how people think about it.

0:11:03.728,0:11:07.537
There is also a rare thing[br]called temporal lobe epilepsy,

0:11:07.561,0:11:09.976
and sometimes, if one has this,

0:11:10.000,0:11:12.597
one may feel oneself transported back

0:11:12.621,0:11:15.025
to a time and place in the past.

0:11:15.049,0:11:17.518
You're at a particular road junction.

0:11:17.542,0:11:19.569
You smell chestnuts roasting.

0:11:19.593,0:11:22.839
You hear the traffic.[br]All the senses are involved.

0:11:22.863,0:11:24.573
And you're waiting for your girl.

0:11:24.597,0:11:28.786
And it's that Tuesday[br]evening back in 1982.

0:11:28.810,0:11:32.708
The temporal lobe hallucinations[br]are all sense hallucinations,

0:11:32.732,0:11:35.269
full of feeling, full of familiarity,

0:11:35.293,0:11:37.360
located in space and time,

0:11:37.384,0:11:39.088
coherent, dramatic.

0:11:39.614,0:11:41.976
The Charles Bonnet[br]ones are quite different.

0:11:42.398,0:11:47.847
In the Charles Bonnet hallucinations,[br]you have all sorts of level,

0:11:47.871,0:11:49.976
from the geometrical hallucinations --

0:11:50.000,0:11:53.264
the pink and blue squares the woman had --

0:11:53.288,0:11:57.735
up to quite elaborate hallucinations

0:11:57.759,0:12:00.440
with figures and especially faces.

0:12:00.464,0:12:03.576
Faces, and sometimes deformed faces,

0:12:03.600,0:12:06.291
are the single commonest thing

0:12:06.315,0:12:08.038
in these hallucinations.

0:12:08.062,0:12:10.976
And one of the second[br]commonest is cartoons.

0:12:11.404,0:12:14.240
So, what is going on?

0:12:14.264,0:12:16.255
Fascinatingly, in the last few years,

0:12:16.279,0:12:20.198
it's been possible to do[br]functional brain imagery,

0:12:20.222,0:12:24.975
to do fMRI on people[br]as they are hallucinating,

0:12:24.999,0:12:31.164
and, in fact, to find that different parts[br]of the visual brain are activated

0:12:31.188,0:12:33.024
as they are hallucinating.

0:12:33.048,0:12:36.398
When people have these[br]simple geometrical hallucinations,

0:12:36.422,0:12:39.976
the primary visual cortex is activated.

0:12:40.000,0:12:43.736
This is the part of the brain[br]which perceives edges and patterns.

0:12:43.760,0:12:47.768
You don't form images[br]with your primary visual cortex.

0:12:47.792,0:12:49.289
When images are formed,

0:12:50.138,0:12:54.811
a higher part of the visual cortex[br]is involved in the temporal lobe.

0:12:54.835,0:12:58.818
And in particular,[br]one area of the temporal lobe

0:12:58.842,0:13:01.691
is called the fusiform gyrus.

0:13:01.715,0:13:05.362
And it's known that if people[br]have damage in the fusiform gyrus,

0:13:05.386,0:13:08.795
they may lose the ability[br]to recognize faces.

0:13:09.533,0:13:13.105
But if there's an abnormal activity[br]in the fusiform gyrus,

0:13:13.129,0:13:15.287
they may hallucinate faces,

0:13:15.311,0:13:18.513
and this is exactly what you find[br]in some of these people.

0:13:18.537,0:13:22.720
There is an area[br]in the anterior part of this gyrus

0:13:22.744,0:13:26.976
where teeth and eyes are represented,

0:13:27.000,0:13:30.093
and that part of the gyrus is activated

0:13:30.117,0:13:34.405
when people get[br]the deformed hallucinations.

0:13:34.429,0:13:38.226
There is another part of the brain[br]which is especially activated

0:13:38.250,0:13:40.226
when one sees cartoons.

0:13:40.713,0:13:43.598
It's activated when[br]one recognizes cartoons,

0:13:43.622,0:13:46.852
when one draws cartoons[br]and when one hallucinates them.

0:13:46.876,0:13:50.132
It's very interesting[br]that that should be specific.

0:13:50.156,0:13:53.284
There are other parts of the brain[br]which are specifically involved

0:13:53.308,0:13:57.795
with the recognition and hallucination[br]of buildings and landscapes.

0:13:57.819,0:14:01.757
Around 1970, it was found that there were[br]not only parts of the brain,

0:14:01.781,0:14:03.661
but particular cells.

0:14:03.685,0:14:07.869
"Face cells" were discovered around 1970.

0:14:07.893,0:14:11.979
And now we know that there are[br]hundreds of other sorts of cells,

0:14:12.003,0:14:14.257
which can be very, very specific.

0:14:14.281,0:14:21.253
So you may not only have "car" cells,[br]you may have "Aston Martin" cells.

0:14:21.277,0:14:23.551
(Laughter)

0:14:23.575,0:14:26.797
I saw an Aston Martin this morning.[br]I had to bring it in.

0:14:26.821,0:14:27.844
(Laughter)

0:14:27.868,0:14:30.684
And now it's in there somewhere.

0:14:30.708,0:14:31.866
So --

0:14:31.890,0:14:33.354
(Laughter)

0:14:33.378,0:14:37.885
now, at this level, in what's called[br]the inferotemporal cortex,

0:14:37.909,0:14:40.417
there are only visual images,

0:14:40.441,0:14:43.013
or figments or fragments.

0:14:43.037,0:14:48.226
It's only at higher levels[br]that the other senses join in

0:14:48.250,0:14:51.023
and there are connections[br]with memory and emotion.

0:14:51.047,0:14:52.748
And in the Charles Bonnet syndrome,

0:14:52.772,0:14:55.142
you don't go to those higher levels.

0:14:55.166,0:14:58.022
You're in these levels[br]of inferior visual cortex,

0:14:58.046,0:15:00.722
where you have thousands[br]and tens of thousands

0:15:00.746,0:15:03.063
and millions of images,

0:15:03.087,0:15:05.493
or figments or fragmentary figments,

0:15:05.517,0:15:11.314
all neurally encoded in particular cells[br]or small clusters of cells.

0:15:11.687,0:15:17.076
Normally, these are all part[br]of the integrated stream of perception,

0:15:17.100,0:15:18.773
or imagination,

0:15:18.797,0:15:20.835
and one is not conscious of them.

0:15:20.859,0:15:24.934
It is only if one is[br]visually impaired or blind

0:15:24.958,0:15:27.528
that the process is interrupted.

0:15:27.552,0:15:30.025
And instead of getting normal perception,

0:15:30.049,0:15:32.588
you're getting an anarchic,

0:15:32.612,0:15:35.601
convulsive stimulation, or release,

0:15:35.625,0:15:39.492
of all of these visual cells[br]in the inferotemporal cortex.

0:15:39.516,0:15:42.305
So, suddenly you see a face.[br]Suddenly you see a car.

0:15:42.329,0:15:45.043
Suddenly this and suddenly that.

0:15:45.067,0:15:47.440
The mind does its best to organize

0:15:47.464,0:15:50.142
and to give some sort[br]of coherence to this,

0:15:50.166,0:15:52.705
but not terribly successfully.

0:15:52.729,0:15:54.377
When these were first described,

0:15:54.401,0:15:57.966
it was thought that they could be[br]interpreted like dreams.

0:15:57.990,0:15:59.816
But, in fact, people say,

0:15:59.840,0:16:04.252
"I don't recognize the people.[br]I can't form any associations."

0:16:04.276,0:16:06.226
"Kermit means nothing to me."

0:16:06.250,0:16:11.481
You don't get anywhere[br]thinking of them as dreams.

0:16:11.925,0:16:16.226
Well, I've more or less[br]said what I wanted.

0:16:16.250,0:16:21.164
I think I just want to recapitulate[br]and say this is common.

0:16:21.188,0:16:22.967
Think of the number of blind people.

0:16:22.991,0:16:25.582
There must be hundreds[br]of thousands of blind people

0:16:25.606,0:16:27.320
who have these hallucinations

0:16:27.344,0:16:29.465
but are too scared to mention them.

0:16:29.489,0:16:34.977
So this sort of thing needs[br]to be brought into notice,

0:16:35.001,0:16:37.432
for patients, for doctors, for the public.

0:16:37.813,0:16:42.839
Finally, I think they are[br]infinitely interesting and valuable,

0:16:42.863,0:16:47.137
for giving one some insight[br]as to how the brain works.

0:16:47.161,0:16:50.758
Charles Bonnet said, 250 years ago --

0:16:50.782,0:16:54.226
he wondered how,[br]thinking of these hallucinations,

0:16:54.250,0:16:56.930
how, as he put it, the theater of the mind

0:16:56.954,0:17:00.304
could be generated[br]by the machinery of the brain.

0:17:00.804,0:17:03.226
Now, 250 years later,

0:17:03.250,0:17:06.536
I think we're beginning[br]to glimpse how this is done.

0:17:06.560,0:17:07.760
Thanks very much.

0:17:07.784,0:17:10.761
(Applause)

0:17:10.785,0:17:13.762
Chris Anderson: That was superb.[br]Thank you so much.

0:17:13.786,0:17:16.836
You speak about these things[br]with so much insight

0:17:16.860,0:17:19.226
and empathy for your patients.

0:17:19.623,0:17:23.443
Have you yourself experienced[br]any of the syndromes you write about?

0:17:23.467,0:17:25.684
Oliver Sacks: I was afraid you'd ask that.

0:17:25.708,0:17:27.536
(Laughter)

0:17:27.560,0:17:29.928
Well, yeah, a lot of them.

0:17:29.952,0:17:33.019
And, actually, I'm a little[br]visually impaired myself.

0:17:33.043,0:17:36.226
I'm blind in one eye[br]and not terribly good in the other.

0:17:36.250,0:17:40.300
And I see the geometrical hallucinations.

0:17:40.324,0:17:41.797
But they stop there.

0:17:41.821,0:17:43.714
CA: And they don't disturb you?

0:17:43.738,0:17:46.977
Because you understand what's doing it,[br]it doesn't make you worried?

0:17:47.001,0:17:50.226
OS: Well, they don't disturb me[br]any more than my tinnitus,

0:17:50.250,0:17:53.355
which I ignore.

0:17:53.379,0:17:55.067
They occasionally interest me,

0:17:55.091,0:17:58.000
and I have many pictures[br]of them in my notebooks.

0:17:58.024,0:18:00.876
I've gone and had an fMRI myself,

0:18:00.900,0:18:03.955
to see how my visual cortex[br]is taking over.

0:18:03.979,0:18:08.133
And when I see all these hexagons

0:18:08.157,0:18:10.226
and complex things, which I also have,

0:18:10.250,0:18:12.013
in visual migraine,

0:18:12.037,0:18:14.489
I wonder whether everyone[br]sees things like this

0:18:14.513,0:18:17.463
and whether things[br]like cave art or ornamental art

0:18:17.487,0:18:19.561
may have been derived from them a bit.

0:18:20.059,0:18:22.481
CA: That was an utterly,[br]utterly fascinating talk.

0:18:22.505,0:18:24.317
Thank you so much for sharing.

0:18:24.341,0:18:25.921
OS: Thank you. Thank you.

0:18:25.945,0:18:27.945
(Applause)