WEBVTT 00:00:00.000 --> 00:00:03.000 We see with the eyes, 00:00:03.000 --> 00:00:06.000 but we see with the brain as well. 00:00:06.000 --> 00:00:10.000 And seeing with the brain is often called imagination. 00:00:10.000 --> 00:00:15.000 And we are familiar with the landscapes of our own imagination, 00:00:15.000 --> 00:00:19.000 our inscapes. We've lived with them all our lives. 00:00:19.000 --> 00:00:23.000 But there are also hallucinations as well, 00:00:23.000 --> 00:00:26.000 and hallucinations are completely different. 00:00:26.000 --> 00:00:28.000 They don't seem to be of our creation. 00:00:28.000 --> 00:00:30.000 They don't seem to be under our control. 00:00:30.000 --> 00:00:32.000 They seem to come from the outside, 00:00:32.000 --> 00:00:35.000 and to mimic perception. NOTE Paragraph 00:00:35.000 --> 00:00:39.000 So I am going to be talking about hallucinations, 00:00:39.000 --> 00:00:43.000 and a particular sort of visual hallucination 00:00:43.000 --> 00:00:48.000 which I see among my patients. 00:00:48.000 --> 00:00:52.000 A few months ago, I got a phone call 00:00:52.000 --> 00:00:54.000 from a nursing home where I work. 00:00:54.000 --> 00:00:59.000 They told me that one of their residents, an old lady in her 90s, 00:00:59.000 --> 00:01:01.000 was seeing things, 00:01:01.000 --> 00:01:04.000 and they wondered if she'd gone bonkers 00:01:04.000 --> 00:01:06.000 or, because she was an old lady, 00:01:06.000 --> 00:01:09.000 whether she'd had a stroke, or whether she had Alzheimer's. NOTE Paragraph 00:01:09.000 --> 00:01:14.000 And so they asked me if I would come and see Rosalie, 00:01:14.000 --> 00:01:16.000 the old lady. 00:01:16.000 --> 00:01:18.000 I went in to see her. 00:01:18.000 --> 00:01:20.000 It was evident straight away 00:01:20.000 --> 00:01:23.000 that she was perfectly sane 00:01:23.000 --> 00:01:26.000 and lucid and of good intelligence, 00:01:26.000 --> 00:01:30.000 but she'd been very startled and very bewildered, 00:01:30.000 --> 00:01:33.000 because she'd been seeing things. 00:01:33.000 --> 00:01:36.000 And she told me -- 00:01:36.000 --> 00:01:38.000 the nurses hadn't mentioned this -- 00:01:38.000 --> 00:01:40.000 that she was blind, 00:01:40.000 --> 00:01:45.000 that she had been completely blind from macular degeneration for five years. 00:01:45.000 --> 00:01:48.000 But now, for the last few days, she'd been seeing things. NOTE Paragraph 00:01:48.000 --> 00:01:51.000 So I said, "What sort of things?" 00:01:51.000 --> 00:01:54.000 And she said, "People in Eastern dress, 00:01:54.000 --> 00:01:58.000 in drapes, walking up and down stairs. 00:01:58.000 --> 00:02:01.000 A man who turns towards me and smiles. 00:02:01.000 --> 00:02:05.000 But he has huge teeth on one side of his mouth. 00:02:05.000 --> 00:02:07.000 Animals too. 00:02:07.000 --> 00:02:10.000 I see a white building. It's snowing, a soft snow. 00:02:10.000 --> 00:02:15.000 I see this horse with a harness, dragging the snow away. 00:02:15.000 --> 00:02:19.000 Then, one night, the scene changes. 00:02:19.000 --> 00:02:21.000 I see cats and dogs walking towards me. 00:02:21.000 --> 00:02:24.000 They come to a certain point and then stop. 00:02:24.000 --> 00:02:26.000 Then it changes again. 00:02:26.000 --> 00:02:29.000 I see a lot of children. They are walking up and down stairs. 00:02:29.000 --> 00:02:32.000 They wear bright colors, rose and blue, 00:02:32.000 --> 00:02:35.000 like Eastern dress." NOTE Paragraph 00:02:35.000 --> 00:02:38.000 Sometimes, she said, before the people come on, 00:02:38.000 --> 00:02:42.000 she may hallucinate pink and blue squares on the floor, 00:02:42.000 --> 00:02:45.000 which seem to go up to the ceiling. 00:02:45.000 --> 00:02:49.000 I said, "Is this like a dream?" 00:02:49.000 --> 00:02:52.000 And she said, "No, it's not like a dream. It's like a movie." 00:02:52.000 --> 00:02:55.000 She said, "It's got color. It's got motion. 00:02:55.000 --> 00:02:59.000 But it's completely silent, like a silent movie." 00:02:59.000 --> 00:03:01.000 And she said that it's a rather boring movie. 00:03:01.000 --> 00:03:04.000 She said, "All these people with Eastern dress, 00:03:04.000 --> 00:03:09.000 walking up and down, very repetitive, very limited." 00:03:09.000 --> 00:03:11.000 (Laughter) NOTE Paragraph 00:03:11.000 --> 00:03:13.000 And she has a sense of humor. 00:03:13.000 --> 00:03:15.000 She knew it was a hallucination. 00:03:15.000 --> 00:03:17.000 But she was frightened. She'd lived 95 years 00:03:17.000 --> 00:03:20.000 and she'd never had a hallucination before. 00:03:20.000 --> 00:03:23.000 She said that the hallucinations were unrelated 00:03:23.000 --> 00:03:27.000 to anything she was thinking or feeling or doing, 00:03:27.000 --> 00:03:31.000 that they seemed to come on by themselves, or disappear. 00:03:31.000 --> 00:03:33.000 She had no control over them. 00:03:33.000 --> 00:03:35.000 She said she didn't recognize 00:03:35.000 --> 00:03:37.000 any of the people or places 00:03:37.000 --> 00:03:39.000 in the hallucinations. 00:03:39.000 --> 00:03:41.000 And none of the people or the animals, 00:03:41.000 --> 00:03:45.000 well, they all seemed oblivious of her. 00:03:45.000 --> 00:03:47.000 And she didn't know what was going on. 00:03:47.000 --> 00:03:49.000 She wondered if she was going mad 00:03:49.000 --> 00:03:51.000 or losing her mind. NOTE Paragraph 00:03:51.000 --> 00:03:53.000 Well, I examined her carefully. 00:03:53.000 --> 00:03:55.000 She was a bright old lady, 00:03:55.000 --> 00:03:59.000 perfectly sane. She had no medical problems. 00:03:59.000 --> 00:04:03.000 She wasn't on any medications which could produce hallucinations. 00:04:03.000 --> 00:04:05.000 But she was blind. 00:04:05.000 --> 00:04:07.000 And I then said to her, 00:04:07.000 --> 00:04:09.000 "I think I know what you have." 00:04:09.000 --> 00:04:13.000 I said, "There is a special form of visual hallucination 00:04:13.000 --> 00:04:17.000 which may go with deteriorating vision or blindness. 00:04:17.000 --> 00:04:20.000 This was originally described," I said, 00:04:20.000 --> 00:04:22.000 "right back in the 18th century, 00:04:22.000 --> 00:04:25.000 by a man called Charles Bonnet. 00:04:25.000 --> 00:04:28.000 And you have Charles Bonnet syndrome. 00:04:28.000 --> 00:04:30.000 There is nothing wrong with your brain. There is nothing wrong with your mind. 00:04:30.000 --> 00:04:33.000 You have Charles Bonnet syndrome." NOTE Paragraph 00:04:33.000 --> 00:04:36.000 And she was very relieved at this, 00:04:36.000 --> 00:04:40.000 that there was nothing seriously the matter, 00:04:40.000 --> 00:04:43.000 and also rather curious. 00:04:43.000 --> 00:04:45.000 She said, "Who is this Charles Bonnet?" 00:04:45.000 --> 00:04:48.000 She said, "Did he have them himself?" 00:04:48.000 --> 00:04:51.000 And she said, "Tell all the nurses 00:04:51.000 --> 00:04:54.000 that I have Charles Bonnet syndrome." 00:04:54.000 --> 00:04:56.000 (Laughter) 00:04:56.000 --> 00:05:00.000 "I'm not crazy. I'm not demented. I have Charles Bonnet syndrome." 00:05:00.000 --> 00:05:02.000 Well, so I did tell the nurses. NOTE Paragraph 00:05:02.000 --> 00:05:05.000 Now this, for me, is a common situation. 00:05:05.000 --> 00:05:07.000 I work in old-age homes, largely. 00:05:07.000 --> 00:05:09.000 I see a lot of elderly people 00:05:09.000 --> 00:05:13.000 who are hearing impaired or visually impaired. 00:05:13.000 --> 00:05:15.000 About 10 percent of the hearing impaired people 00:05:15.000 --> 00:05:18.000 get musical hallucinations. 00:05:18.000 --> 00:05:21.000 And about 10 percent of the visually impaired people 00:05:21.000 --> 00:05:23.000 get visual hallucinations. 00:05:23.000 --> 00:05:25.000 You don't have to be completely blind, 00:05:25.000 --> 00:05:27.000 only sufficiently impaired. NOTE Paragraph 00:05:27.000 --> 00:05:31.000 Now with the original description in the 18th century, 00:05:31.000 --> 00:05:33.000 Charles Bonnet did not have them. 00:05:33.000 --> 00:05:36.000 His grandfather had these hallucinations. 00:05:36.000 --> 00:05:39.000 His grandfather was a magistrate, an elderly man. 00:05:39.000 --> 00:05:42.000 He'd had cataract surgery. 00:05:42.000 --> 00:05:44.000 His vision was pretty poor. 00:05:44.000 --> 00:05:49.000 And in 1759, he described to his grandson 00:05:49.000 --> 00:05:51.000 various things he was seeing. NOTE Paragraph 00:05:51.000 --> 00:05:53.000 The first thing he said was he saw 00:05:53.000 --> 00:05:55.000 a handkerchief in midair. 00:05:55.000 --> 00:05:57.000 It was a large blue handkerchief 00:05:57.000 --> 00:05:59.000 with four orange circles. 00:05:59.000 --> 00:06:02.000 And he knew it was a hallucination. 00:06:02.000 --> 00:06:04.000 You don't have handkerchiefs in midair. 00:06:04.000 --> 00:06:08.000 And then he saw a big wheel in midair. 00:06:08.000 --> 00:06:13.000 But sometimes he wasn't sure whether he was hallucinating or not, 00:06:13.000 --> 00:06:15.000 because the hallucinations would fit 00:06:15.000 --> 00:06:17.000 in the context of the visions. 00:06:17.000 --> 00:06:20.000 So on one occasion, when his granddaughters were visiting them, 00:06:20.000 --> 00:06:25.000 he said, "And who are these handsome young men with you?" 00:06:25.000 --> 00:06:29.000 And they said, "Alas, Grandpapa, there are no handsome young men." 00:06:29.000 --> 00:06:33.000 And then the handsome young men disappeared. 00:06:33.000 --> 00:06:36.000 It's typical of these hallucinations 00:06:36.000 --> 00:06:39.000 that they may come in a flash and disappear in a flash. 00:06:39.000 --> 00:06:41.000 They don't usually fade in and out. 00:06:41.000 --> 00:06:44.000 They are rather sudden, and they change suddenly. NOTE Paragraph 00:06:44.000 --> 00:06:47.000 Charles Lullin, the grandfather, 00:06:47.000 --> 00:06:50.000 saw hundreds of different figures, 00:06:50.000 --> 00:06:52.000 different landscapes of all sorts. 00:06:52.000 --> 00:06:56.000 On one occasion, he saw a man in a bathrobe smoking a pipe, 00:06:56.000 --> 00:06:59.000 and realized it was himself. 00:06:59.000 --> 00:07:02.000 That was the only figure he recognized. 00:07:02.000 --> 00:07:06.000 On one occasion when he was walking in the streets of Paris, 00:07:06.000 --> 00:07:09.000 he saw -- this was real -- a scaffolding. 00:07:09.000 --> 00:07:12.000 But when he got back home, he saw a miniature of the scaffolding 00:07:12.000 --> 00:07:16.000 six inches high, on his study table. 00:07:16.000 --> 00:07:19.000 This repetition of perception 00:07:19.000 --> 00:07:21.000 is sometimes called palinopsia. NOTE Paragraph 00:07:21.000 --> 00:07:26.000 With him and with Rosalie, 00:07:26.000 --> 00:07:28.000 what seems to be going on -- 00:07:28.000 --> 00:07:30.000 and Rosalie said, "What's going on?" -- 00:07:30.000 --> 00:07:33.000 and I said that as you lose vision, 00:07:33.000 --> 00:07:36.000 as the visual parts of the brain are no longer getting any input, 00:07:36.000 --> 00:07:39.000 they become hyperactive and excitable, 00:07:39.000 --> 00:07:41.000 and they start to fire spontaneously. 00:07:41.000 --> 00:07:44.000 And you start to see things. 00:07:44.000 --> 00:07:47.000 The things you see can be very complicated indeed. NOTE Paragraph 00:07:47.000 --> 00:07:51.000 With another patient of mine, 00:07:51.000 --> 00:07:53.000 who, also had some vision, 00:07:53.000 --> 00:07:57.000 the vision she had could be disturbing. 00:07:57.000 --> 00:08:00.000 On one occasion, she said she saw 00:08:00.000 --> 00:08:03.000 a man in a striped shirt in a restaurant. 00:08:03.000 --> 00:08:05.000 And he turned around. And then 00:08:05.000 --> 00:08:08.000 he divided into six figures in striped shirts, 00:08:08.000 --> 00:08:11.000 who started walking towards her. 00:08:11.000 --> 00:08:14.000 And then the six figures came together again, like a concertina. 00:08:14.000 --> 00:08:16.000 Once, when she was driving, 00:08:16.000 --> 00:08:18.000 or rather, her husband was driving, 00:08:18.000 --> 00:08:20.000 the road divided into four 00:08:20.000 --> 00:08:24.000 and she felt herself going simultaneously up four roads. NOTE Paragraph 00:08:24.000 --> 00:08:29.000 She had very mobile hallucinations as well. 00:08:29.000 --> 00:08:32.000 A lot of them had to do with a car. 00:08:32.000 --> 00:08:34.000 Sometimes she would see a teenage boy 00:08:34.000 --> 00:08:37.000 sitting on the hood of the car. 00:08:37.000 --> 00:08:39.000 He was very tenacious and he moved rather gracefully 00:08:39.000 --> 00:08:41.000 when the car turned. 00:08:41.000 --> 00:08:44.000 And then when they came to a stop, 00:08:44.000 --> 00:08:47.000 the boy would do a sudden vertical takeoff, 100 foot in the air, 00:08:47.000 --> 00:08:50.000 and then disappear. NOTE Paragraph 00:08:50.000 --> 00:08:55.000 Another patient of mine had a different sort of hallucination. 00:08:55.000 --> 00:08:58.000 This was a woman who didn't have trouble with her eyes, 00:08:58.000 --> 00:09:00.000 but the visual parts of her brain, 00:09:00.000 --> 00:09:03.000 a little tumor in the occipital cortex. 00:09:03.000 --> 00:09:08.000 And, above all, she would see cartoons. 00:09:08.000 --> 00:09:13.000 These cartoons would be transparent 00:09:13.000 --> 00:09:16.000 and would cover half the visual field, like a screen. 00:09:16.000 --> 00:09:22.000 And especially she saw cartoons of Kermit the Frog. 00:09:22.000 --> 00:09:23.000 (Laughter) 00:09:23.000 --> 00:09:26.000 Now, I don't watch Sesame Street, 00:09:26.000 --> 00:09:29.000 but she made a point of saying, 00:09:29.000 --> 00:09:33.000 "Why Kermit?" She said, "Kermit the Frog means nothing to me. 00:09:33.000 --> 00:09:36.000 You know, I was wondering about Freudian determinants. 00:09:36.000 --> 00:09:38.000 Why Kermit? 00:09:38.000 --> 00:09:40.000 Kermit the Frog means nothing to me." NOTE Paragraph 00:09:40.000 --> 00:09:42.000 She didn't mind the cartoons too much. 00:09:42.000 --> 00:09:46.000 But what did disturb her was she got very persistent 00:09:46.000 --> 00:09:49.000 images or hallucinations of faces 00:09:49.000 --> 00:09:52.000 and as with Rosalie, the faces were often deformed, 00:09:52.000 --> 00:09:56.000 with very large teeth or very large eyes. 00:09:56.000 --> 00:09:59.000 And these frightened her. 00:09:59.000 --> 00:10:03.000 Well, what is going on with these people? 00:10:03.000 --> 00:10:06.000 As a physician, I have to try and define what's going on, 00:10:06.000 --> 00:10:08.000 and to reassure people, 00:10:08.000 --> 00:10:12.000 especially to reassure them that they're not going insane. NOTE Paragraph 00:10:12.000 --> 00:10:15.000 Something like 10 percent, as I said, 00:10:15.000 --> 00:10:18.000 of visually impaired people get these. 00:10:18.000 --> 00:10:22.000 But no more than one percent of the people acknowledge them, 00:10:22.000 --> 00:10:25.000 because they are afraid they will be seen as insane or something. 00:10:25.000 --> 00:10:27.000 And if they do mention them to their own doctors 00:10:27.000 --> 00:10:30.000 they may be misdiagnosed. NOTE Paragraph 00:10:30.000 --> 00:10:32.000 In particular, the notion is that if you see 00:10:32.000 --> 00:10:35.000 things or hear things, you're going mad, 00:10:35.000 --> 00:10:38.000 but the psychotic hallucinations are quite different. 00:10:38.000 --> 00:10:41.000 Psychotic hallucinations, whether they are visual or vocal, 00:10:41.000 --> 00:10:43.000 they address you. They accuse you. 00:10:43.000 --> 00:10:45.000 They seduce you. They humiliate you. 00:10:45.000 --> 00:10:48.000 They jeer at you. 00:10:48.000 --> 00:10:50.000 You interact with them. 00:10:50.000 --> 00:10:53.000 There is none of this quality of being addressed 00:10:53.000 --> 00:10:56.000 with these Charles Bonnet hallucinations. 00:10:56.000 --> 00:11:00.000 There is a film. You're seeing a film which has nothing to do with you, 00:11:00.000 --> 00:11:03.000 or that's how people think about it. NOTE Paragraph 00:11:03.000 --> 00:11:07.000 There is also a rare thing called temporal lobe epilepsy, 00:11:07.000 --> 00:11:10.000 and sometimes, if one has this, 00:11:10.000 --> 00:11:12.000 one may feel oneself transported back 00:11:12.000 --> 00:11:15.000 to a time and place in the past. 00:11:15.000 --> 00:11:17.000 You're at a particular road junction. 00:11:17.000 --> 00:11:19.000 You smell chestnuts roasting. 00:11:19.000 --> 00:11:22.000 You hear the traffic. All the senses are involved. 00:11:22.000 --> 00:11:24.000 And you're waiting for your girl. 00:11:24.000 --> 00:11:28.000 And it's that Tuesday evening back in 1982. 00:11:28.000 --> 00:11:30.000 And the temporal lobe hallucinations 00:11:30.000 --> 00:11:32.000 are all-sense hallucinations, 00:11:32.000 --> 00:11:35.000 full of feeling, full of familiarity, 00:11:35.000 --> 00:11:37.000 located in space and time, 00:11:37.000 --> 00:11:39.000 coherent, dramatic. 00:11:39.000 --> 00:11:42.000 The Charles Bonnet ones are quite different. NOTE Paragraph 00:11:42.000 --> 00:11:46.000 So in the Charles Bonnet hallucinations, 00:11:46.000 --> 00:11:48.000 you have all sorts of levels, 00:11:48.000 --> 00:11:50.000 from the geometrical hallucinations -- 00:11:50.000 --> 00:11:53.000 the pink and blue squares the woman had -- 00:11:53.000 --> 00:11:57.000 up to quite elaborate hallucinations 00:11:57.000 --> 00:12:00.000 with figures and especially faces. 00:12:00.000 --> 00:12:03.000 Faces, and sometimes deformed faces, 00:12:03.000 --> 00:12:06.000 are the single commonest thing 00:12:06.000 --> 00:12:08.000 in these hallucinations. 00:12:08.000 --> 00:12:11.000 And one of the second commonest is cartoons. NOTE Paragraph 00:12:11.000 --> 00:12:14.000 So, what is going on? 00:12:14.000 --> 00:12:16.000 Fascinatingly, in the last few years, 00:12:16.000 --> 00:12:20.000 it's been possible to do functional brain imagery, 00:12:20.000 --> 00:12:24.000 to do fMRI on people as they are hallucinating. 00:12:24.000 --> 00:12:28.000 And in fact, to find that different parts 00:12:28.000 --> 00:12:31.000 of the visual brain are activated 00:12:31.000 --> 00:12:33.000 as they are hallucinating. 00:12:33.000 --> 00:12:36.000 When people have these simple geometrical hallucinations, 00:12:36.000 --> 00:12:40.000 the primary visual cortex is activated. 00:12:40.000 --> 00:12:43.000 This is the part of the brain which perceives edges and patterns. 00:12:43.000 --> 00:12:47.000 You don't form images with your primary visual cortex. NOTE Paragraph 00:12:47.000 --> 00:12:50.000 When images are formed, 00:12:50.000 --> 00:12:52.000 a higher part of the visual cortex 00:12:52.000 --> 00:12:54.000 is involved in the temporal lobe. 00:12:54.000 --> 00:12:59.000 And in particular, one area of the temporal lobe 00:12:59.000 --> 00:13:01.000 is called the fusiform gyrus. 00:13:01.000 --> 00:13:05.000 And it's known that if people have damage in the fusiform gyrus, 00:13:05.000 --> 00:13:09.000 they maybe lose the ability to recognize faces. 00:13:09.000 --> 00:13:13.000 But if there is an abnormal activity in the fusiform gyrus, 00:13:13.000 --> 00:13:15.000 they may hallucinate faces, 00:13:15.000 --> 00:13:18.000 and this is exactly what you find in some of these people. 00:13:18.000 --> 00:13:22.000 There is an area in the anterior part of this gyrus 00:13:22.000 --> 00:13:27.000 where teeth and eyes are represented, 00:13:27.000 --> 00:13:30.000 and that part of the gyrus is activated 00:13:30.000 --> 00:13:34.000 when people get the deformed hallucinations. NOTE Paragraph 00:13:34.000 --> 00:13:36.000 There is another part of the brain 00:13:36.000 --> 00:13:38.000 which is especially activated 00:13:38.000 --> 00:13:40.000 when one sees cartoons. 00:13:40.000 --> 00:13:43.000 It's activated when one recognizes cartoons, 00:13:43.000 --> 00:13:47.000 when one draws cartoons, and when one hallucinates them. 00:13:47.000 --> 00:13:50.000 It's very interesting that that should be specific. 00:13:50.000 --> 00:13:53.000 There are other parts of the brain which are specifically involved 00:13:53.000 --> 00:13:55.000 with the recognition and hallucination 00:13:55.000 --> 00:13:58.000 of buildings and landscapes. NOTE Paragraph 00:13:58.000 --> 00:14:01.000 Around 1970, it was found that there were not only parts of the brain, 00:14:01.000 --> 00:14:03.000 but particular cells. 00:14:03.000 --> 00:14:08.000 "Face cells" were discovered around 1970. 00:14:08.000 --> 00:14:10.000 And now we know that there are hundreds of other 00:14:10.000 --> 00:14:12.000 sorts of cells, 00:14:12.000 --> 00:14:14.000 which can be very, very specific. 00:14:14.000 --> 00:14:16.000 So you may not only have 00:14:16.000 --> 00:14:18.000 "car" cells, 00:14:18.000 --> 00:14:21.000 you may have "Aston Martin" cells. 00:14:21.000 --> 00:14:23.000 (Laughter) 00:14:23.000 --> 00:14:25.000 I saw an Aston Martin this morning. 00:14:25.000 --> 00:14:27.000 I had to bring it in. 00:14:27.000 --> 00:14:30.000 And now it's in there somewhere. 00:14:30.000 --> 00:14:33.000 (Laughter) NOTE Paragraph 00:14:33.000 --> 00:14:37.000 Now, at this level, in what's called the inferotemporal cortex, 00:14:37.000 --> 00:14:40.000 there are only visual images, 00:14:40.000 --> 00:14:43.000 or figments or fragments. 00:14:43.000 --> 00:14:46.000 It's only at higher levels 00:14:46.000 --> 00:14:48.000 that the other senses join in 00:14:48.000 --> 00:14:50.000 and there are connections with memory and emotion. 00:14:50.000 --> 00:14:53.000 And in the Charles Bonnet syndrome, 00:14:53.000 --> 00:14:55.000 you don't go to those higher levels. 00:14:55.000 --> 00:14:58.000 You're in these levels of inferior visual cortex 00:14:58.000 --> 00:15:00.000 where you have thousands and tens of thousands 00:15:00.000 --> 00:15:03.000 and millions of images, 00:15:03.000 --> 00:15:05.000 or figments, or fragmentary figments, 00:15:05.000 --> 00:15:07.000 all neurally encoded 00:15:07.000 --> 00:15:11.000 in particular cells or small clusters of cells. NOTE Paragraph 00:15:11.000 --> 00:15:14.000 Normally these are all part of 00:15:14.000 --> 00:15:18.000 the integrated stream of perception, or imagination, 00:15:18.000 --> 00:15:21.000 and one is not conscious of them. 00:15:21.000 --> 00:15:25.000 It is only if one is visually impaired or blind 00:15:25.000 --> 00:15:27.000 that the process is interrupted. 00:15:27.000 --> 00:15:30.000 And instead of getting normal perception, 00:15:30.000 --> 00:15:32.000 you're getting an anarchic, 00:15:32.000 --> 00:15:35.000 convulsive stimulation, or release, 00:15:35.000 --> 00:15:37.000 of all of these visual cells 00:15:37.000 --> 00:15:39.000 in the inferotemporal cortex. 00:15:39.000 --> 00:15:42.000 So, suddenly you see a face. Suddenly you see a car. 00:15:42.000 --> 00:15:45.000 Suddenly this, and suddenly that. 00:15:45.000 --> 00:15:47.000 The mind does its best to organize 00:15:47.000 --> 00:15:50.000 and to give some sort of coherence to this, 00:15:50.000 --> 00:15:52.000 but not terribly successfully. NOTE Paragraph 00:15:52.000 --> 00:15:54.000 When these were first described, 00:15:54.000 --> 00:15:58.000 it was thought that they could be interpreted like dreams. 00:15:58.000 --> 00:16:00.000 But in fact people say, 00:16:00.000 --> 00:16:03.000 "I don't recognize the people. I can't form any associations." 00:16:03.000 --> 00:16:06.000 "Kermit means nothing to me." 00:16:06.000 --> 00:16:11.000 You don't get anywhere thinking of them as dreams. NOTE Paragraph 00:16:11.000 --> 00:16:16.000 Well, I've more or less said what I wanted. 00:16:16.000 --> 00:16:19.000 I think I just want to recapitulate 00:16:19.000 --> 00:16:21.000 and say this is common. 00:16:21.000 --> 00:16:23.000 Think of the number of blind people. 00:16:23.000 --> 00:16:25.000 There must be hundreds of thousands of blind people 00:16:25.000 --> 00:16:27.000 who have these hallucinations, 00:16:27.000 --> 00:16:29.000 but are too scared to mention them. 00:16:29.000 --> 00:16:32.000 So this sort of thing needs to be brought into 00:16:32.000 --> 00:16:38.000 notice, for patients, for doctors, for the public. 00:16:38.000 --> 00:16:40.000 Finally, I think they are 00:16:40.000 --> 00:16:43.000 infinitely interesting and valuable, 00:16:43.000 --> 00:16:47.000 for giving one some insight as to how the brain works. NOTE Paragraph 00:16:47.000 --> 00:16:50.000 Charles Bonnet said, 250 years ago -- 00:16:50.000 --> 00:16:54.000 he wondered how, thinking these hallucinations, 00:16:54.000 --> 00:16:57.000 how, as he put it, the theater of the mind 00:16:57.000 --> 00:17:00.000 could be generated by the machinery of the brain. 00:17:00.000 --> 00:17:03.000 Now, 250 years later, 00:17:03.000 --> 00:17:06.000 I think we're beginning to glimpse how this is done. 00:17:06.000 --> 00:17:08.000 Thanks very much. NOTE Paragraph 00:17:08.000 --> 00:17:11.000 (Applause) NOTE Paragraph 00:17:11.000 --> 00:17:14.000 Chris Anderson: That was superb. Thank you so much. 00:17:14.000 --> 00:17:16.000 You speak about these things with so much insight 00:17:16.000 --> 00:17:19.000 and empathy for your patients. 00:17:19.000 --> 00:17:24.000 Have you yourself experienced any of the syndromes you write about? NOTE Paragraph 00:17:24.000 --> 00:17:26.000 Oliver Sacks: I was afraid you'd ask that. 00:17:26.000 --> 00:17:27.000 (Laughter) 00:17:27.000 --> 00:17:30.000 Well, yeah, a lot of them. 00:17:30.000 --> 00:17:33.000 And actually I'm a little visually impaired myself. 00:17:33.000 --> 00:17:36.000 I'm blind in one eye, and not terribly good in the other. 00:17:36.000 --> 00:17:40.000 And I see the geometrical hallucinations. 00:17:40.000 --> 00:17:42.000 But they stop there. NOTE Paragraph 00:17:42.000 --> 00:17:44.000 CA: And they don't disturb you? 00:17:44.000 --> 00:17:46.000 Because you understand what's doing it, it doesn't make you worried? NOTE Paragraph 00:17:46.000 --> 00:17:50.000 OS: Well they don't disturb me any more than my tinnitus, 00:17:50.000 --> 00:17:53.000 which I ignore. 00:17:53.000 --> 00:17:55.000 They occasionally interest me, 00:17:55.000 --> 00:17:58.000 and I have many pictures of them in my notebooks. 00:17:58.000 --> 00:18:01.000 I've gone and had an fMRI myself, 00:18:01.000 --> 00:18:04.000 to see how my visual cortex is taking over. 00:18:04.000 --> 00:18:08.000 And when I see all these hexagons 00:18:08.000 --> 00:18:10.000 and complex things, which I also have, 00:18:10.000 --> 00:18:12.000 in visual migraine, 00:18:12.000 --> 00:18:14.000 I wonder whether everyone sees things like this, 00:18:14.000 --> 00:18:17.000 and whether things like cave art or ornamental art 00:18:17.000 --> 00:18:20.000 may have been derived from them a bit. NOTE Paragraph 00:18:20.000 --> 00:18:22.000 CA: That was an utterly, utterly fascinating talk. 00:18:22.000 --> 00:18:24.000 Thank you so much for sharing. NOTE Paragraph 00:18:24.000 --> 00:18:26.000 OS: Thank you. Thank you. 00:18:26.000 --> 00:18:28.000 (Applause)