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Oliver Sacks: Hallucinations


This is SCIENCE FRIDAY. I'm Flora Lichtman. In his new book "Hallucinations," Oliver Sacks writes that you see with your brain, not with your eyes. And his book suggests our brains can play some bizarre tricks on us. Dr. Sacks describes a musician who sees intricate but unplayable sheet music superimposed on his field of vision.

There's a patient who smells roast beef every time a migraine is coming on. The famous botanist Carl Linnaeus was visited by his own doppelganger. In fact, he'd spot himself picking flowers beside him. He even, Linnaeus, even entered his own classroom to find himself already there. Imagine that.

Sacks writes that some illusions occur with medical conditions: migraines, narcolepsy, Parkinson's, epilepsy. Some are caused by psychedelic drugs like LSD. But for many hallucinations, the cause is not well-understood. If you have a question for Dr. Sacks, please give us a ring. Our number is 1-800-989-TALK, 1-800-989-8255. Or tweet us @scifri.

And let me introduce Dr. Sacks now. He's the author of "Hallucinations," and you may know him also as the author of "Musicophilia" and "Awakenings." He's a professor of neurology at New York University School of Medicine, and he joins us here in our New York studios. Welcome to SCIENCE FRIDAY, Dr. Sacks.

DR. OLIVER SACKS: It's a pleasure being here again.

LICHTMAN: Oh, it's great to have you back. So I don't know if this is the right word, favorite hallucination, but were - which of them in the list that you detail in the book sort of jump out as the most interesting or ones that caught you by surprise yourself?

SACKS: I think among the most curious are the sort which Linnaeus had in which one sees oneself, and a self which often precisely mirrors one's expressions and gestures. But I think they're all fascinating, all 800 sorts.


LICHTMAN: The one with Linnaeus was kind of interesting, and other ones like that, because people who suffer from these hallucinations sometimes can't tell which one of them is real.

SACKS: Yes, there's a more malignant variety of this, in which one seems sometimes to look out through the eyes of a double, and you're not sure which - if you're real, or you are the double. And this has always been a stimulus to gothic fiction about doubles. So Dostoyevsky and Edgar Allan Poe and de Maupassant and others have seized this as a ground for fiction.

LICHTMAN: Many of the hallucinations that you write about in the book, auditory and visual, come when someone loses a sense. Why is that?

SACKS: I think it's because the relevant part of the brain, whether it's the visual or the auditory part, is incessantly active, implacably active. It's always processing. And if it doesn't have anything or enough to process from the outside, it'll dip into the inside and dip into memory, mine things, although they're then reassembled and scrambled in peculiar ways.

LICHTMAN: It surprised me that people who are blind have hallucinations and see things vividly even though their eyes don't let them see things.

SACKS: I work, among other places, in some old-age homes, and there a lot of elderly people who are very intact mentally but have impaired vision or blindness. And I - 40 years ago or more, I was struck by how many of these people have hallucinations. They may not mention this spontaneously. People don't mention hallucinations spontaneously, but when they got to know me, or if I asked, then things would come out.

And the visual hallucinations of the blind in fact were described right back in the 18th century by a naturalist called Charles Bonnet, and we speak of them as Charles Bonnet syndrome.

LICHTMAN: Were these patients glad to have some sort of vision back, even if it was hallucinatory?

SACKS: I - patients may vary, but in general after being very startled and frightened and wondering what's going on and wondering if it could have ominous meaning, once they're reassured, I think they may get used to it and even welcome it in a way. One of my correspondents imagined his eyes saying to him we know blindness is no fun, so we've arranged this small syndrome as a sort of coda to your sighted life. It's not much, but it's the best we can do.

LICHTMAN: One of the other types of hallucinations that seems relevant here is that people hallucinate, I read in "Hallucinations," your book, people that they've lost, people who have died who have been in their lives. Is this sort of the same phenomenon at play, you're missing someone and so you make them up?

SACKS: Well, one would certainly wonder if it's that way, a death of a loved and familiar person leaves a hole in one's life, and visual or auditory hallucinations of the dead person are surprisingly common. They may affect something like a third of people who are bereaved. And they're often felt to be comforting and part of the mourning process, especially common in the first year or so after a death.

LICHTMAN: People in your book even hallucinated their dead cats.

SACKS: Yes, I've got - to my surprise I have four cat hallucinations in the book, two on the basis of bereavement and two on other bases.


LICHTMAN: I wonder if this is also - you know, I think people notice when they're missing someone, they tend to see them out and about or mistake people for the person that they're missing. Is this related? Is that a sort of minor hallucination?

SACKS: Well, this is very common indeed. I know after my mother died, I kept thinking I was seeing her in the street. I think there was probably some slight similarity of gait or posture or size. I suppose one would call these illusions rather than hallucinations. An illusion is seeing something wrong, whereas a hallucination is invented, it comes out of the blue.

LICHTMAN: Do you have to see something to hallucinate it? Do you have to have had that imagery in your mind before to bring it back?

SACKS: Yes, I think so. It's difficult to know how, say, the congenitally deaf could imagine or dream or hallucinate any sounds or the congenitally blind any sights.

LICHTMAN: Have there been studies about - cross-cultural studies? Do people in China hallucinate different things than people in Spain, for example?

SACKS: There - I think there are quite a lot of trans-cultural studies, and I'm afraid I'm more ignorant than I should be. It is very common for people with Charles Bonnet syndrome here to hallucinate rather elaborate, often 17th-century figures in sort of foppish dress with big headdresses.

I had a brother who was a physician in Australia, and I asked him to investigate this among the Aborigines there, but I didn't get a clear answer. But I think that there has to be cultural shaping of a particular sort of hallucination, though the major sorts, I think, are neurological categories.

There may be patterns, there may be faces. There may be, as you said, hallucinations of musical notation or letters, and all of these go with abnormal activity in particular parts of the brain.

LICHTMAN: How much do we understand about what in the brain actually is causing these hallucinations?

SACKS: Well, in the last 10 or 12 years, we've been able to do functional brain imagery on people as they have hallucinations. And one can find, say, heightened activity in what's called the face area, the fusiform face area, on the right side of the brain, when people hallucinate faces or a comparable area on the left side when they hallucinate text.

Why these areas should be activated may have different explanations. Sometimes there may actually be something wrong there, and there's a hemorrhage or a seizure focus, but sometimes, as with the sense-deprived people, it's just as if normal constraints have been removed and a whole area has sort of become anarchically active and is just doing its thing.

LICHTMAN: I wonder if that lets people see things that you could never see in real life because the outside world wouldn't produce those patterns in your brain?

SACKS: Yes. I think this is one of the fascinating things about hallucination, that it can go beyond imagination and beyond experience. I had one hallucination myself in which I saw a color, a sort of indigo which I'd never seen before and basically have never seen since, but it was cooked up by my brain.

LICHTMAN: Tell us the story of that experience.

SACKS: Well, I was back in my relative youth. This was back in 1964. I was doing neurology residency, and I'm - I hit various drugs over the weekends, partly for fun, partly out of curiosity, partly in the hope of stimulating some creative spark in myself. And on one occasion, I developed a sort of pharmacological launch pad of amphetamine and LSD and cannabis. And when I was really stoned, I said I want to see indigo now. And as if thrown by a giant paint brush, a huge trembling pear-shaped blob of the purest blue appeared.

It was both luminous and, it seemed to me, numinous as well. It seemed to have a sort of mystic or religious beauty. I thought to myself this is the color of heaven, which is an odd thought for an old Jewish atheist.


SACKS: But it was there for about five seconds, and then it disappeared. And I had a great sense of loss, although curiously I did once see it again. And the second time, I had no drugs in me, but I had gone to a concert, and I was transported by the music. The concert was near the Egyptology gallery in the museum here. And this transported state I wandered in and there were little lapis lazuli amulets and so forth. And they shone with indigo, and I thought it really exists. But then I - at the end of the concert, I went back, and they were just mauve or puce.

LICHTMAN: A different kind of drug, maybe, producing those colors?

SACKS: Well, certainly, the - some of the same systems in the brain, reward systems, pleasure centers, whatever one calls them, and even parts of the brain which may have to do with mystical or religious consciousness can be stimulated various ways, whether it's a drug or music or meditation or hypnosis.

LICHTMAN: You're listening to SCIENCE FRIDAY on NPR. I'm Flora Lichtman talking with Oliver Sacks about his book "Hallucinations." And let's go to the phones because I know a lot of people are going to want to talk to you about this. Zach(ph) from Dayton, Ohio, you're on SCIENCE FRIDAY.

ZACH: Hi. Thanks for taking my call.

LICHTMAN: Go ahead.

ZACH: I was just wondering if he could talk about if we know the exact mechanism of how LSD and other similar drugs work, and also, what's going on in the brain when one experiences a flashback when you're not actually under the influence of the drug?

SACKS: Well, unfortunately, serious research on LSD more or less came to an end in the 1960s, basically because Timothy Leary and others sort of spoiled the whole area. And it's thought that LSD and DMT and some other drugs probably affect the serotonin system of the brain, but the amphetamines and cocaine probably affect the dopamine system of the brain. But, you know, we now know 20 or 30 different neurotransmitters, and they have very complex interactions.

And I think a short answer is that it's difficult to define. It may vary at different times, as well as in different people. The business of a flashback you mentioned is very interesting and can be very dangerous. This became obvious in the Vietnam War when some veterans would come back who had been blown up or been in hideous situations, and they may suddenly feel themselves again in that situation and feel all the people around them were Viet Cong, and if they had a gun, open fire.

We don't know exactly what happens in these flashbacks, which can occur in various situations, but there must be some sudden physiological change. I don't think anything can happen in the mind which is not mirrored in the brain.

LICHTMAN: Did you have any experiences with LSD during that period that you described earlier?

SACKS: Yes. LSD played a part in the indigo experience, but some other experiences...

LICHTMAN: I wonder if the flashbacks are, you know, you - it sounds like PTSD, if you might see some of the same brain regions activated?

SACKS: Well, it's difficult to have someone in a functional MRI with an unpredictable event like a flashback, but it is certainly very much as if there's an activation of some of the same regions.

LICHTMAN: You mentioned that LSD hasn't really been seriously studied, and it seems like this is true for hallucinations, too, to some degree. Is that right?

SACKS: There's some - strangely, this is the year of hallucinations because beside my book, there are two marvelous books from Holland out on the subject. One of them is called "A Dictionary of Hallucinations." But I think, often, hallucinations are not taken too seriously. And if a patient mentions them, they may be dismissed. But they seem to me of enormous interest, and I think they are beginning to be restudied again.

LICHTMAN: And maybe more common, then, than we're led to be believe or that most people think.

SACKS: Oh, absolutely. I think probably almost everybody has occasionally experienced a sort of hallucination when they're lying in bed waiting for sleep. Often then, one can see geometrical patterns or faces very, very quickly changing. You don't feel that they're in the room, but you don't have any control over them. And they're not like - it's not like imagination, and it's not like dreaming. It's a - but census - I can't pronounce the plural of census.


LICHTMAN: Well, we'll figure that one out and come back right after the break.

SACKS: But a census was done in the 1890s and asked some people whether they heard or saw things while awake and sane, and the answer is that close to 12 percent of the population did.

LICHTMAN: More on that in a moment.


LICHTMAN: This is SCIENCE FRIDAY. I'm Flora Lichtman. We're talking this hour about "Hallucinations," a new book by neurologist and author Oliver Sacks. And let's go to the phones, so people can ask you some questions. Tom in Long Island, do you have a question?

TOM: Yeah. Hi. Thanks for taking my call. I was wondering about the relationship between the brain chemistry associated with hallucinations and that of deja vu. As I have recurring deja vu and I've had it for periods up to several hours long, and it certainly feels similar to hallucinations, which I have also experienced.

SACKS: I think one could call deja vu a hallucination or at least an illusion of familiarity that things have happened before. You've seen this. You've said this. Everyone has this occasionally. I think if one has it more than occasionally, one may wonder what's happening in the brain. In people who have temporal lobe epilepsy, deja vu may be common and may be the first sign or symptom. But sometimes as people get older, they will have more deja vu. But other than saying that both deja vu and jamais vu are associated with memory systems and familiarity systems of the temporal lobes and the hippocampal system, I can't say anymore.

LICHTMAN: Julianne(ph) in Boston, do you have a question?

JULIANNE: I do. Thank you for taking my call. I was curious. I am a synesthete, and I also suffer from optical migraines. And I was wondering if the synesthesia had in any way affected the fact that I have optical migraines or vice versa.

SACKS: Well, I think you are doubly blessed or doubly cursed or however you like to put it.


SACKS: I don't know that there's any consistent relationship. The synesthesia is now recognized, like hallucinations, to be much commoner than was thought. About four or five years ago, the frequency was put up from one in 2,000 to one in 20; it was realized to be 100 times commoner. But I don't know whether there's any connection. People have very various attitudes to synesthesia. Some people love it. Some hate it. Some are indifferent. Some people can employ it as an aid to memory. It seems to be built in and congenital and very consistent throughout life. It's often familial. And I think it's - this is not the case with visual migraine.

LICHTMAN: Julianne, what's your synesthesia like, if you don't mind sharing?

JULIANNE: So the synesthesia that I experience, actually I love the fact that I have it because I'm also colorblind, and my synesthesia allows me to experience colors that I otherwise would never get to see. When I hear music, I see colors. And people's names have smells and textures and sometimes tastes that go with them. It's a really overwhelming and beautiful experience every day for me.

SACKS: And an unearthly one if you see colors which you have never seen in the physical world. I know some people with this will speak about Martian colors. And one can also hear sounds and smell smells which are almost indescribable. But I'm glad you have a rich and, above all, enjoyable synesthesia.

JULIANNE: Oh, I am as well.

LICHTMAN: Thank you for calling, Julianne.

JULIANNE: Thank you so much for taking my call.

LICHTMAN: What about these olfactory illusions? I had never heard of that, but you apparently smell buttered toast, I think.

SACKS: Yeah. Well, I also have migraine auras, and they are usually visual. But I've occasionally had other sensations. On one occasion, I smelled hot buttered toast and had almost a sort of deja vu feeling that I was a 2-year-old about to be put in a high chair and given hot buttered toast. This occurred when I was in the hospital. And I was sniffing constantly and went in search of hot buttered toast, which I couldn't find. It didn't quite occur to me then that it was a hallucination. I thought I was just associating to something which was there. But the second time, I was driving on the Bronx River Parkway and there's no hot buttered toast there.

Olfactory hallucinations are common and, in fact, diagnostic in a certain sort of epilepsy. Temporal lobe seizures are very often ushered in by smells. But probably the commonest olfactory hallucinations are in the five percent or so of the population who, for one reason or another, have lost or impaired their sense of smell.

LICHTMAN: What about schizophrenia? I think people have heard that hallucinations are common with that illness. Is that true? Universally true, I should say?

SACKS: Well, I've avoided schizophrenia and schizophrenic hallucinations for the most part here, because I think it needs a whole book to itself. But certainly, it's much commoner for schizophrenic hallucinations, if they occur, to be auditory and to take the form of voices and often unpleasant voices, which can accuse one or abuse one or jeer at one. The hallucinations are directed at one where, say, the hallucinations in Charles Bonnet syndrome are like film strips which have nothing to do with one.

There was a famous study in which the subjects pretended to be patients and to have heard voices even though their behavior and their histories were not in the least suggestive of any mental aberration. But just because they complained of hearing voices, all of them were immediately hospitalized and given drugs for schizophrenia or psychosis. While, you know, a high percentage of people in acute schizophrenic states may hear voices, the majority of people who hear voices are not schizophrenic, and probably almost everyone has heard their name called once in a while.

LICHTMAN: This is a topic that - this is part of it that really interests me, what - how you draw the line between a hallucination and what we all experience every day. And let me give you an example I was thinking about. When people fall in love, we seem to think that things look more beautiful, like the afternoon or the trees take on a new sparkle. You know, it - it's almost a cliche, but couldn't it be true that in our minds, they actually are more beautiful because of the brain chemistry?

SACKS: Oh, I'm sure sensations and emotions are enhanced when one is in love. And the touch of the beloved is ecstatic and all the reward systems of the brain are working overtime when one is in love. This is a strongly hyper-physiological state as well a, you know, a lyrical and beautiful one.

LICHTMAN: And yet, we don't call, you know, we don't call them hallucinations.

SACKS: No. Well, I think they're not hallucinations. They're enhancements.

LICHTMAN: So how do you draw - how do you distinguish between one and the other?

SACKS: I am - if I see a sky blue cow in mid-air suddenly, that's a hallucination. Hallucinations come from nowhere. And for the most part, they are unrelated to what one is doing or thinking or feeling. They appear suddenly. They are involuntary. One has no control over them. And they're often enormously detailed in a way which images are not. And they're autonomous. They do their own thing.

LICHTMAN: Yeah. That is a sort of bizarre part of it. You watch them going on around you but you can't control them.


LICHTMAN: I wanted to read a little passage from your book that's really struck me as I was reading. But first, tell me if I'm pronouncing the person's name right, Edward Liveing?

SACKS: Liveing, yes.

LICHTMAN: OK. So I'm going to read a passage and then ask you about it. A century had passed since Liveing worked and wrote in London. Rousing myself from my reverie of being Liveing or one of his contemporaries, I came to and said to myself, now it's the 1960s, not the 1860s. Who could be the Liveing of our time? A disingenuous clutter of names spoke themselves in my mind. I thought of Dr. A, Dr. B, Dr. C, Dr. D, all of them good men, but none of them with that mix of science and humanism that was so powerful in Liveing. And then a very loud internal voice said, you silly bugger. You're the man.

And when I was reading this, what struck as so moving is that here we are 50 years later, and you are the man.

SACKS: Well, that - that mad-sounding episode or manic-sounding episode was when I was under a very large dose of amphetamine, which made Liveing and his works sort of, you know, enchanting and which in a way triggered my own resolution to write. And I started writing my first book, on migraine, under that stimulus, and I've gone on from there and have not taken drugs again. That final drug experience, I think, did what I hoped drugs might do, which was, you know, got the imagination and the mind going again in a way which it hadn't been doing in the somewhat depressive years before that.

Having said that, I do not at all recommend...


SACKS: ...to anyone that they do things like this. I am - I took large doses of things by myself. It was very dangerous. I'm lucky to have survived. And quite a number of my friends who did this did not survive. And so there are better ways to come alive than taking drugs.

LICHTMAN: Do you wonder what would have happened if you hadn't had that epiphany?

SACKS: I think it probably would have happened anyhow but less suddenly and less extravagantly and less manically.

LICHTMAN: One thing in that passage that you note is the humanism of Liveing. And reading your books, I think, it's - no one can ignore the fact that you treat your patients so kindly in how you describe them. I wondered if that just come - if it comes out that way or if that's something that you consider.

SACKS: Well, I saw this with my parents, who were both physicians and how often their patients would become very dear to them, although this dearness must never compromise one's judgment.

A lot of medicine now consists of large statistical studies, and these may be extremely important. For example, one could never have shown that tobacco was related to bronchial cancer without a huge statistical study. But for myself, the individual person and their story is always central. And I care for them, and I don't think medicine or medical care is possible without a deep caring.

LICHTMAN: That comes through. You're listening to SCIENCE FRIDAY on NPR. I'm Flora Lichtman, talking with Oliver Sacks about his new book, "Hallucinations," which is terrific, by the way. Were people reticent to share their stories about hallucinations?

SACKS: Often. I saw with my - I've seen with my own patients how years may go past without the secret hallucinations being divulged. But when there's a relationship of trust and delicate inquiry and sometimes avoiding the word hallucination, which can sound ominous, then one starts to realize how common things are. For example, close to 15 percent of people who are visually impaired or lost their sight completely have elaborate hallucinations, and 80 percent of them have simple ones, geometric ones. I'm one of those 80 percent myself.

LICHTMAN: You write in the book, especially as a young man, that when you weren't working, you would get unmoored and feel empty. I suspect that that may still be true. Is it?

SACKS: Yes, I think it is. I love working, and I'm very lucky that my work gives me joy and sometimes gives other people joy. But a mischievous spirit gets into me when I'm idle. And I much prefer the week from Monday to Friday to the weekend.

LICHTMAN: On that note, what's next for you?

SACKS: I'm not quite sure. I'm going to have to wait for another epiphany, although there's part of me which wants to have a little holiday from neurology and do something quite different. And I always keep journals when I travel and maybe a book of travel journals.

LICHTMAN: Do you have any top destinations before we have to go?

SACKS: Well, my last visit was in Iceland and - but I'm particularly fond of the north. I have a Tromso journal, and I have a Costa Rica journal. One of my journals was published, which was my Oaxaca journal. But I love reading journals and I love writing them.

LICHTMAN: Well, I hope we can look forward to that. Thank you so much for joining us on the show today, Dr. Sacks.

SACKS: I've enjoyed it very much. Thank you.

LICHTMAN: Oliver Sacks is the author of "Hallucinations," "Musicophilia," "Awakenings" and many other books. He's also a professor of neurology at New York University School of Medicine.

Go to our website if you want to see Dr. Sacks' desk. I had the pleasure of visiting Dr. Sacks in his office a couple of years ago, and we put together a video where we get a personal tour of the objects that Dr. Sacks surrounds himself with. It will not disappoint you, I don't think. Transcript provided by NPR, Copyright NPR.