by Oliver Sacks
Natural selection could show me how cows in general had come to be, but neural Darwinism was necessary to apprehend what it was like to be this particular cow. Becoming this particular cow was made possible by experience selecting particular neuronal groups in its brain and amplifying their activity.
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Mammals, birds, and some reptiles, Edelman speculated, have “primary consciousness,” the ability to create mental scenes to help them adapt to complex and changing environments. This achievement, for Edelman, depended upon the emergence of a new type of neuronal circuit at some “transcendent moment” in evolution—a circuit allowing massive, parallel, reciprocal connections between neuronal maps, as well as among the ongoing global mappings that integrate new experiences and recategorize categories.
At some second transcendent moment in evolution, Edelman proposed, the development of “higher-order consciousness” was made possible in humans (and perhaps a few other species including apes and dolphins) by a higher level of reentrant signaling. Higher-order consciousness brings an unprecedented power of generalization and reflection, of recognizing past and future, so that finally self-consciousness, the awareness of being a self in the world, is achieved.
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In 1992, I went with Gerry to a conference on consciousness at Jesus College in Cambridge. While Gerry’s books were often difficult to read, seeing and hearing him speak gave a feeling of revelation to many in the audience.
At that same meeting—I forget what prompted the exchange—Gerry said to me, “You’re no theoretician.”
“I know,” I said, “but I am a field-worker, and you need the sort of fieldwork I do for the sort of theory making you do.” Gerry agreed.
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I often encounter situations in day-to-day neurological practice which completely defeat classical neurological explanations and cry out for explanations of a radically different kind, but many such phenomena can be explained, in Edelmanian terms, as breakdowns in local or higher-order mapping consequent upon nerve damage or disease.
When, after injury and immobility following my accident in Norway, my left leg became “alien,” my neurological knowledge did not help; classical neurology had nothing to say about the relation of sensation to knowledge and to self, about how, if the flow of neural information is impaired, a limb may be lost to consciousness and to self, “disowned,” and how there may then be a rapid remapping of the rest of the body which excludes that limb.
If the right hemisphere of the brain is badly damaged in its sensory (parietal) areas, patients may show an “anosognosia,” an unawareness that anything is the matter, even though the left side of their body is senseless or paralyzed. Sometimes they may insist that their own left side belongs to “someone else.” For such patients, subjectively, their space and world are entire, even though they are living in a hemi-world. For many years, anosognosia was misinterpreted as a bizarre neurotic symptom, since it was unintelligible in terms of classical neurology. But Edelman sees such a condition as a “disease of consciousness,” a total breakdown of high-level reentrant signaling and mapping in one hemisphere and a radical reorganization of consciousness in consequence.
Sometimes following a neurological lesion, a dissociation occurs between memory and consciousness, leaving only implicit knowledge or memory. Thus my patient Jimmie, the amnesic mariner, had no explicit memory of Kennedy’s assassination, and when I asked him whether any president had been assassinated in the twentieth century, he would say, “No, not that I know of.” But if I asked him, “Hypothetically, then, if a presidential assassination had somehow occurred without your knowledge, where might you guess it occurred: New York, Chicago, Dallas, New Orleans, or San Francisco?” he would invariably “guess” correctly, Dallas.
Similarly, patients with total cortical blindness due to massive damage to the primary visual areas of the brain will assert that they can see nothing, but they may also mysteriously “guess” correctly what lies before them—so-called blindsight. In all these cases, perception and perceptual categorization have been preserved but have been divorced from higher-order consciousness.
Individuality is deeply imbued in us from the very start, at the neuronal level. Even at a motor level, researchers have shown, an infant does not follow a set pattern of learning to walk or how to reach for something. Each baby experiments with different ways of reaching for objects and over the course of several months discovers or selects his own motor solutions. When we try to envisage the neural basis of such individual learning, we might imagine a “population” of movements (and their neural correlates) being strengthened or pruned away by experience.
Similar considerations arise with regard to recovery and rehabilitation after strokes and other injuries. There are no rules; there is no prescribed path of recovery; every patient must discover or create his own motor and perceptual patterns, his own solutions to the challenges that face him; and it is the function of a sensitive therapist to help him in this.
And in its broadest sense, neural Darwinism implies that we are destined, whether we wish it or not, to a life of particularity and self-development, to make our own individual paths through life.
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When I read Neural Darwinism, I wondered if it would change the face of neuroscience as Darwin’s theory had changed the face of biology. The short, but inadequate, answer is that it has not, although there are now countless scientists who take for granted many of Edelman’s ideas without acknowledging, or perhaps even knowing, that they are Edelman’s. In this sense, his thinking, though not explicitly acknowledged, has been shifting the very grounds of neuroscience.
In the 1980s, Edelman’s theory was so novel that it could not easily be fitted into any of the existing models, the paradigms, of neuroscience, and it was this, I think, which prevented its wide acceptance—coupled with Edelman’s at times dense and difficult writing. Edelman’s theory was “premature,” so ahead of its time, so complex and demanding of new ways of thinking, that it was resisted, or ignored, in the 1980s, but in the next twenty or thirty years, with new technologies, we will be in a good position to verify (or disprove) its ultimate tenets. It remains, for me, the most powerful and elegant explanation of how we humans and our brains construct our very individual selves and worlds.
1. He was fascinated when I showed him the complex patterns one might see in a migraine aura—hexagons and geometrical patterns of many shapes, including fractal patterns. He was able to simulate some of these basic patterns on a neural network, and in 1992 we included this work as an appendix to a revised edition of Migraine. Ralph’s mathematical and physical intuition also led him to feel that chaos and self-organization might be central to natural processes of all kinds, relevant to every sort of science from quantum mechanics to neuroscience, and this led in 1990 to another collaboration between us, an appendix for a revised edition of Awakenings, “Chaos and Awakenings.”
2. A few days later, I got a reply in which Crick sought more detail about the difference between my migraine patients and a remarkable patient described in a 1983 paper by Josef Zihl and his colleagues. Zihl’s patient, for example, could not pour a cup of tea; she saw a motionless “glacier” of tea hanging from the spout. Some of my migraine patients had experienced such “stills” in rapid succession, whereas for Zihl’s patient, who had acquired motion blindness following a stroke, the stills apparently lasted much longer, perhaps several seconds each. In particular, Crick wanted to know whether successive stills in my migraine patients occurred within the interval between successive eye movements or only between such intervals. “I would very much like to discuss these topics with you,” he wrote, “including your remarks about color as a cerebro-mental construct.”
Writing back to Crick, I enlarged on the deep differences between my migraine patients and Zihl’s motion-blind woman.
3. Gerry had a rapt but puzzled audience, and when he said, “The mind is not a computer, the world is not a piece of tape,” his
Italian audience misheard this as “The world is not a piece of cake.” This led to passionate discussions in the corridors as to what the great American professor meant by this gnomic statement.
4. Edelman had originally pioneered a selectionist theory in relation to the immune system—he was awarded a Nobel Prize for this work—and then, in the mid-1970s, started to apply analogous concepts to the nervous system.
Home
I sometimes felt that I had left England in an underhand way. I had had the best of English educations, had absorbed the best of English diction and prose, the habits and traditions of a thousand years, and here I was taking this precious mental cargo, everything that had been invested in me, out of the country, without so much as a “Thank you” or a “Good-bye.”
Nonetheless, I continued to regard England as home, returned as frequently as I could, and felt stronger—a better writer—whenever my feet were planted on home ground. I kept in close touch with my relatives, friends, and colleagues in England and made belief that my ten, my twenty, my thirty years in America were nothing more than an extended visit and that, sooner or later, I would return home.
My sense of England as “home” took a beating in 1990, when my father died and the house on Mapesbury Road—where I was born and brought up and which I revisited and often stayed in when I returned to England, the house of which every inch was suffused for me with memories and emotions—was sold. I no longer felt I had a place to go back to, and my visits thereafter felt like visits and not like returns to my own country and people.
I was strangely proud, nonetheless, of my U.K. passport, which (prior to 2000) had beautiful large, stiff boards embossed with gold lettering, very different from the flimsy little things issued by most countries. I did not seek American citizenship and was happy to have a green card, to be accounted a “resident alien.” This accorded with how I felt, at least for much of the time—a friendly, observant alien noting everything around me but without civic responsibilities such as voting or jury duty or need to affiliate myself with the country’s policies or politics. I often felt (as Temple Grandin said of herself) that I was an anthropologist on Mars. (I had much less of this feeling in my California days, when I felt at one with the mountains, the forests, and the deserts of the West.)
And then, in June of 2008, to my surprise, I heard that my name was in the Queen’s Birthday Honours List—that I was to become a Commander of the Order of the British Empire. The term “commander” tickled me—I could not imagine myself as a commander on the bridge of a destroyer or a battleship—but I was curiously and rather deeply moved by the honor.
Though I am not given to formal clothes or other formalities—normally, my clothes are sloppy and decrepit, and I have only one suit—I enjoyed the formalities in Buckingham Palace: being instructed how to bow, how to walk backwards before the queen, how to await her taking one’s hand or addressing one. (The royal person was not to be touched, or spoken to, unbidden.) I was half-afraid that I would do something awful, like faint or fart right in front of the queen, but all went well. During the ceremony, I was very impressed by the queen’s stamina: by the time I was called up, she had been standing erect, without support, for more than two hours (there were two hundred honorees that day). She spoke to me briefly but warmly, asking me what I was working on. I had the feeling of a very decent, friendly person with a sense of humor. It was as if she—and England—were saying, “You have done useful, honorable work. Come home. All is forgiven.”
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Medical life, seeing patients, was not displaced by the writing of Seeing Voices, of Island, or of Uncle Tungsten. I continued to see patients at Beth Abraham, the Little Sisters, and elsewhere.
In the summer of 2005, I went to England to visit Clive Wearing, the extraordinary amnesic musician who had been the subject of Jonathan Miller’s 1986 film, Prisoner of Consciousness. Clive’s wife, Deborah (with whom I had corresponded over the years), had just published a remarkable book about him, and she hoped I might now see what he was like twenty years after his disastrous encephalitis. While he could remember almost nothing of his adult life and could hold on to new events for no more than a few seconds, Clive could still play the organ and conduct a choir, just as he had once done as a professional musician. He illustrated the special power of music and of musical memory, and I wanted to write about this. Thinking about this and many other “neuromusical” topics, I felt I should try to put together a book on music and the brain.
Musicophilia, as the book would eventually be called, started out as a modest project; I thought it might be a tiny book, perhaps three chapters. But as I started thinking about people with musical synesthesia; people with amusia, who could not recognize any music; people with frontotemporal dementia who might have a sudden burst or release of unsuspected musical talents and passions; people with musical seizures, or seizures induced by music; and people haunted by “earworms” or repetitive images of music or outright hallucinations of music, the book grew much larger.
I had been fascinated, moreover, by the therapeutic power of music since seeing it in my postencephalitic patients forty years before, even before they were awakened by L-dopa. Since then, I had been struck by the powers of music to help patients with many other conditions: amnesia, aphasia, depression, and even dementia.
Since Hat was first published in 1985, I have received an ever-increasing flow of letters from readers, often offering descriptions of their own experiences. This has extended my practice, so to speak, far beyond the confines of the clinic. Musicophilia (and later Hallucinations) was greatly enriched by some of these letters and reports, no less than by my correspondence and visits with physicians and researchers.
And while I wrote about many new patients and subjects in Musicophilia, I also revisited a number of the patients I had written about earlier, this time focusing on their responses to music and considering them in the light of new forms of brain imaging and concepts of how the brain-mind creates constructs and categories.
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As I entered my seventies, I was in excellent health; I had a few orthopedic problems but nothing serious or life threatening. I did not give much thought to illness or death, even though I had lost all three of my older brothers, as well as many friends and contemporaries.
In December of 2005, however, a cancer made its presence suddenly and dramatically known—a melanoma in my right eye, which presented as a sudden incandescence to one side and then a partial blindness. It had probably been growing slowly for some time and at this point had reached close to the fovea, the tiny central area where vision is most acute. Melanoma has an evil reputation, and when the diagnosis was pronounced, I took it as a death sentence. But ocular melanomas, my doctor quickly said, were relatively benign; they rarely metastasized, and they were eminently treatable.
The cancer was irradiated, then lasered several times, because certain areas kept regrowing. During the first eighteen months of treatment, sight fluctuated in my right eye almost daily, from near blind to near normal, and I would be thrown, with these fluctuations, from terror to relief, then back to terror—from one emotional extreme to another.
This would have been hard to bear (and I would have been even harder to live with) had I not become fascinated by some of the visual phenomena which occurred as, bit by bit, my retina—and eyesight—were nibbled away by the tumor and the lasering: the wild topological distortions, the perversions of color, the clever but automatic filling in of blind spots, the incontinent spread of color and form, the continued perception of objects and scenes when the eyes were closed, and, not least, the varied hallucinations which now swarmed in my ever-larger blind spots. My brain was clearly as involved as the eye itself.
I feared blindness, but I feared death even more, so I made a sort of bargain with the melanoma: take the eye if you must, I told it, but leave the rest of me alone.
In September of 2009, after three and a half years of treatment, the retina in my right eye, fragile
from radiation, hemorrhaged, blinding it completely; attempts to remove the blood failed, because the retina immediately re-bled. Without binocular vision, I now had many new, disabling (but sometimes enthralling!) phenomena to contend with—and investigate. The loss of stereo vision was not only a sad privation for me as a passionate stereophile but often dangerous. Without depth perception, steps and curbs just looked like lines on the ground, and distant objects seemed to be on the same plane as closer ones. With the loss of visual field to my right, I had many accidents, colliding with objects or people who seemed to loom suddenly in front of me out of nowhere. And I was not only physically blind but mentally blind, to the right. I could no longer even imagine the presence of what I could no longer see. Such a hemi-neglect, as neurologists call it, is usually the result of a stroke or a tumor in the visual or parietal areas of the brain. For me, as a neurologist, these phenomena were especially fascinating, for they provided an astonishing panorama of the ways in which the brain works (or misworks, or fails to work) when the input from the senses is deficient or abnormal. I documented all this in minute detail—my melanoma journals ran to ninety thousand words—and studied it, performing perceptual experiments of all sorts. The whole experience, like my “leg” experience, became an experimentum suitatis, an experiment with, or on, myself.
The perceptual consequences of my eye damage constituted a fertile ground of enquiry; I felt as if I were discovering a whole world of strange phenomena, although I could not help thinking that all patients with eye problems like mine surely experienced some of the same perceptual phenomena as I did. Writing of my own experiences, then, I would also be writing for them. But the sense of discovery was exhilarating and kept me going through what might otherwise have been rather fearful and demoralizing years, as did my continuing seeing patients and writing.