A Leg to Stand On

by Oliver Sacks, M. D.

  This hole in memory/identity/space I could now interpret as a hole in what Edelman calls primary consciousness. Higher-order consciousness struggled to comprehend this, using all the concepts and language at its command. Higher-order consciousness gazed into the abyss, could provide concepts or words for what it found (the “alien,” the “anomalous,” the “placeless,” the “pastless”), but could do nothing whatever about it. Nor could higher-order consciousness in any way substitute for it; I could use the symbolic and linguistic construct “leg,” but it lacked all subjective reality for me. Higher-order consciousness is based on primary consciousness, and can only transmit and reflect on it, which meant symbolizing it, here, with metaphors of nonentity. “Nothing,” Beckett reminds us, “is more real than nothing.”

  “Neuropsychological observations,” Edelman stresses, “offer a singular opportunity to test theories of consciousness in terms of modality-specific losses, and effects of disease on memory, language, and skill.” The simplest such “test” turns out to be the sense of alienation, which shows us, by default, the structure of consciousness. Alienation is a focal loss of primary consciousness as this is perceived by a human higher-order consciousness.

  That a local disorder, and a peripheral one at that, can cause a massive disturbance of consciousness may seem exceedingly surprising. But this is because we have not had, hitherto, an adequate “bottom-up” theory of consciousness, have not understood its biological origins in the perceptual processes and their mappings in the organism. Alterations in primary receiving areas—disorders of local mapping—Edelman shows us, are a sufficient cause for alterations of consciousness; it is not necessary to invoke any additional cause, such as a coexisting, “top-down” neurosis or psychosis.*13

  There is indeed a dissociation in alienation. Leont’ev and Zaporozhets call it “a dissociation of gnostic systems,” but really it is a dissociation of consciousness, between a primary consciousness which is totally but locally extinguished and a higher consciousness which can compensate in a way, albeit a thin and unsatisfactory way. (It is similar with patients who have suffered a complete severing of the spinal cord; they lose all primary consciousness of their bodies below the lesion, but maintain a formal, “factual” knowledge of its existence.) In this sense A Leg to Stand On is not just the story of a leg, but an account, from inside, of what primary consciousness is like; an account such as the experience of alienation, and nothing else, can provide.*14

  Primary consciousness, of course, is normally invisible—it is automatic, it conceals itself, like everything normal. Its presence, paradoxically, is self-concealing. And it is only when it breaks down, grossly, that it can become, does become, an object of attention. This is true of all pathology—that in the negative form of disorder, it makes startlingly visible (sometimes terribly visible) what is normally hidden. This is why Hippocrates, 2,500 years ago, spoke of “pathographies” as having a paradoxical power to lift the veil, to reveal the normally hidden structure of body and mind.

  And yet, such pathographies—of the vicissitudes of consciousness, as they are related to neuropsychological conditions—are exceedingly, almost vanishingly, rare. “Such syndromes are common,” Luria wrote to me, in regard to alienation, “but very uncommonly described.”

  “Please publish your observations,” he went on. “It will do something to alter the veterinary approach to peripheral disorders.” A purely “veterinary” approach, it was clear to him, could not begin to comprehend such disorders, for alienation cannot be measured or filmed or seen; it can only be reported, by the experiencer, a conscious human observer. But neurology is largely a veterinary business—it deals almost exclusively with what can be measured and tested; hardly at all with the inner experience, the inner structure, the subjectivity, of the subject. It prides itself on managing to exclude these, on being a wholly “objective” science, on being wholly concerned (like physics) with the public, the visible, the demonstrable. It excludes mental states, consciousness, because they are “subjective” and “private,” and cannot be verified or validated in the conventional way. No “personal” terms are allowed in neurology—“consciousness,” when it is used, denotes only a generalized arousal, as is undermined in states of stupor or coma. We do not have any “neurology of identity.”

  And yet it has always been intuitively clear—and now it is becoming formally clear—that we are in no sense machines or impersonal automata; that all experience, all perception, is self-referential from the start; that our memories are nothing like the memories of computers, but are organizations and categorizations of personal experience; that “space” and “time” are not the space and time of physics, but space and time in reference to ourselves. There is no representation of abstract “space” in the brain—only of our own, individual, “personal space” (as is shown so clearly in the phenomenon of hemi-space extinction, a bisection of a personal model of the world). And it is clear, first and foremost, that our bodies are personal—that they are the first definers of ego or self. (“The ego is first and foremost a body-ego,” as Freud writes.) But none of this has really entered neurology. Neurology still bases itself on a mechanical model, even in the “systems” neuropsychology of Luria and Leont’ev. The mechanical model goes back to Descartes, to his dichotomous division of body and soul, his notion of the body as an automaton, with a knowing-willing “I” somehow floating above it.

  But clinical and personal experience—an experience such as I relate in this book—is totally incompatible with such a duality; it shows the bankruptcy of the classical model, and the need for a personal neurology, for the realization that our nerves and brains are ours from the start, and that in their perceptions and categorizations and memories and models, and in their emergent levels of concept and consciousness, they continue to be ours, to be self-referent through and through.

  It is up to neurology now to make a great jump—to jump from the classical, mechanical model it has espoused for so long to a totally personal, self-referential model of brain and mind. There are many signs, now, that such a transformation may occur. And if it does, so Edelman likes to remark, it will be the most momentous revolution of our time—as revolutionary as the rise of physics, Galilean thinking, four hundred years ago.

  *1 The importance of experiencing such body-image disturbances and alienations—and trying to understand and communicate them—is beginning to be realized in medical education. Thus Dr. Roger Carpenter recently wrote me:

  Here at Cambridge we routinely do a class for all our pre-clinical students in which they inflate a cuff round the arm, and chart the ensuing loss of sensation and motor power. The overt reason for this is of course to practice simple neurological tests; but a hidden benefit is that they learn what it is like to be a patient, to come to terms with a state of internal affairs they have never previously experienced, and attempt to convey their abnormal perceptions to someone else. And nearly all of them report, with some surprise, how they begin to feel alienated from their arm, perceiving it not subjectively as a part of themselves, but objectively as a rather disgusting appendage for which they have no responsibility.

  Perhaps this experience should be made a compulsory component of the training of all doctors!

  *2 I recently received a letter from a neurological colleague, Dr. S. J. Boyson of the University of Colorado, describing how complex a relearning she herself had to go through after a seemingly simple orthopedic injury:

  Four months ago, I had a trimalleolar fracture with almost complete disruption of the joint capsule. Although I have never felt the total alienation you experienced, I still refer to my injured ankle as “it” and I don’t trust it yet. I thought PT would be a matter of regaining range of motion and muscle strength, but I have found that much more is necessary. I too have needed to relearn and rehearse formerly automatic movements. I have been afraid to ride a nonstationary bike or to put myself into o
ther situations where I might have to respond quickly.

  The idea of these movements, she felt, had gone; she had to “reprogram” her brain with them all over again. This, indeed, is the danger of immobility or orthopedic constraint: complex movements not done, not practiced internally (and one cannot imagine movements which are physically impossible), are forgotten within a matter of weeks (or less), and they become neurologically, or neuropsychologically, impossible.

  *3 Luria had asked me in 1974 whether I thought that the leftness of the leg was important—whether, for example, similar syndromes might occur with injury or surgery to the right leg. I could not give him an answer at the time, though his question recurred to me when I found myself, through chance, a “control.” His question was prompted by the fact that the central syndromes of inattention and allesthesia and alienation (Pötzl’s syndrome, etc.) usually affect the left side of the body, and are associated with lesions of the nondominant hemisphere, which, compared to the dominant one, has such a low level of consciousness. Would a higher level of consciousness, he wondered, prevent such a syndrome from occurring on the other side?

  *4 Late in 1983 I sent the British Medical Journal a narrative for their section “Clinical Curios.” They liked it, but rejected it, saying it was far too long. When my right hand was immobilized, I sent them another “clinical curio,” just fifty words long. They were astonished by its brevity, and immediately accepted it; but how, they wondered, did someone of my prolixity rein himself in so severely? When I told them of my accident, and how I was constrained to write with my left hand, they said, “We are sorry about your accident, but it does wonders for your style!”

  *5 “How come all you neurologists go mystical in the end?” the psychoanalyst Carol Feldman once asked me—a question which goes deep into epistemology—and the psyche. See “Neurology and the Soul,” New York Review of Books, November 11, 1990.

  *6 But if this is the case, one might wonder, what about “phantoms”—those strange, fixed images of limbs which can persist for years after their amputation? Fossil images, so to speak, which correspond with no current reality. It seems likely that phantoms are maintained, at least to a considerable extent, by a continuing (albeit pathological) excitation peripherally—for example, in the cut nerves of the limb (and perhaps more centrally); this is especially clear if there is formation of a neuroma in the nerve stump—neuromas tend to give rise to agonizingly painful phantoms. If the peripheral input is stopped, the phantom will disappear—I observed this in one patient with a phantom finger, who lost the phantom as he lost sensation in the fingers from a diabetic neuropathy. Conversely, stimulating a peripheral nerve tends to stimulate the phantom, and may actually be employed for this purpose by amputees, who find that they can use the phantom image for propelling a prosthesis. Phantoms can also be stimulated, or made to vanish, by stimulating or anesthetizing the corresponding spinal roots.

  *7 When writing the original edition of A Leg to Stand On, I thought that a loss of proprioception was a sufficient condition for “disowning” and “alienation.” I now think it sufficient for disowning, but not for alienation. Thus patients with tabes, while they may “lose” their limbs, do not regard them as alien. And Christina, the “disembodied” lady I describe in The Man Who Mistook His Wife for a Hat, while capable (as I saw on several occasions) of mistaking her own hand, when not visually monitored, for somebody else’s, never saw her hand as alien. There may have to be, as Israel Rosenfield postulates, not just a proprioceptive loss, but a loss of pain and other sensations, in order for a limb to be perceived as alien (Rosenfield, 1991).

  But, conversely, it may not be necessary to have any sensory loss for alienation to occur. Thus patients with limbs totally paralyzed by polio sometimes report these limbs as “alien,” even though their sensory capacities are unaffected. Such patients may complain not only of an inability to make a movement, but of an inability to will one, a breakdown in intentionality itself, albeit only in regard to the paralyzed muscles. Since intentionality (in part) defines a “self,” such a breakdown, though local, can in effect split the sense of self, split off a “non-self,” alien part of the body from the rest.

  *8 A student of mine once suffered a severe frostbite, and felt that his fingers had been amputated at the knuckles, leaving him with a hideous, club-shaped monstrosity of a fist. When anesthesia is long-standing, there is great danger of damage to the neglected parts—hence the constant mishaps to the extremities of those with leprosy, which destroys the sensory nerve endings.

  *9 “By self-reference,” Rosenfield writes (1992), “I mean reference to a dynamic body image….Our ‘self’ is determined by the ways in which we use our own bodies, the movements of our bodies in themselves, movements that we acquire over time; and it is this dynamic image to which stimuli are referred (self-reference) and in terms of which the stimuli ‘make sense.’…Every recollection refers not only to the remembered person or object, but the person who is remembering.”

  *10 Could a dog have hysteria, or an alien limb? Could a monkey? Could an ape? What is needed to have hysteria or alienation? My impression is that a dog could not (although Freud’s chow was said to have developed a hysterical pregnancy, which elicited from Freud the ironic remark that “it could only happen in an analyst’s house!”). I think too a monkey, an owl monkey such as Merzenich uses, could not. But I suspect an ape could, could certainly develop an alienated limb, and, less certainly, but just possibly, a hysteria. For both alienation and hysteria, in their quite different ways, depend on the presence of a higher-order, self-referential consciousness—an explicit sense of self—of a sort which seems to be present in apes, but not in any lower animals. Thus, characteristically, apes can recognize themselves in a mirror, whereas monkeys and dogs cannot.

  *11 I describe such a patient in “Eyes Right!” in The Man Who Mistook His Wife for a Hat.

  *12 So too, but in a very different way, is hysteria. Thus the hysteric, while he will complain of his paralyses, anesthesias, etc., remains unaware of their origin in changes of affect and concept, unaware of the changes in his consciousness. Indeed, if such pathogenic changes can be brought to consciousness, the hysteria disappears; the hysteria, therefore, depends on unconsciousness—albeit an unconsciousness quite different from that of the anosognosic.

  *13 Neuropsychological syndromes are “bottom-up” disorders, in which a lower-level neurological disorder causes a higher-level psychological one. Hysteria, by contrast, is a “top-down” disorder, where the primary disturbance occurs at the highest level, in higher-order consciousness, which is symbolic and linguistic; any disturbance at lower levels are secondary to this. There is a primary disturbance of local mapping and primary consciousness in alienation, but no primary disturbance of these in hysteria. (There could, of course, be some secondary disturbance.) Higher-order consciousness (which includes the psychoanalytic “unconscious”) is charged with specific, intense affects in hysteria—whereas it is merely bewildered in alienation.

  *14 We can never know primary consciousness directly, Edelman points out; we can only know it through higher-order consciousness. Animals lacking higher-order consciousness can experience it directly, but cannot report it. If there is any situation in which human beings are able to give a report of pure primary consciousness, uncontaminated by higher-order consciousness, it is, Edelman suggests, in “split-brain” patients, in whom the right hemisphere has been surgically disconnected from the left. Such patients may report perceptions (from the left side of the body, or the left half of the visual field) without their being modulated by the linguistic and reflective powers of the left hemisphere.

  Annotated Bibliography

  The first clear descriptions of paralysis, “shock,” and alienation in limbs, in consequence of peripheral injury, were provided by Silas Weir Mitchell, G. R. Morehouse and W. W. Keen in Reflex Paralysis, put out as a circular (No. 6) by the Surgeon General’s offi
ce on 10 March 1864. (This was reprinted, with an introductory note by J. F. Fulton, in 1941, Historical Library, Yale University School of Medicine.)

  J. Babinski (with J. Froment) published two monographic articles on hysteria (“pithiatism”) and on the central resonances of peripheral injuries (“physiopathies”) seen in the Great War. They later had these bound together in a single volume, as Hystérie-Pithiatism et Troubles Nerveux d’Ordre Réflexe: Syndrome Physiopathique (Paris: Masson, 1917). A translation (by J. D. Rolleston) was published in London the following year, by the University of London Press.

  Henry Head’s incomparable description of the formation of postural schemata (“body-images”) in the brain may be found in his great Studies in Neurology (Oxford: Oxford University Press, 1920), vol. 2, especially on pages 605–608, 669, 722–726 and 754.

  A. N. Leont’ev and A. V. Zaporozhets published their studies of “internal amputation” and alienation (as a consequence of hand injuries and surgery) in Rehabilitation of Hand Function (original Russian edition, 1948; English edition translated by Basil Haigh, edited by W. Ritchie Russell, Oxford and New York: Pergamon Press, 1960). I consider this book an absolute treasure of phenomenological description, and of very acute neuropsychological formulations.

  Gerald M. Edelman’s latest book is The Remembered Present: A Biological Theory of Consciousness (New York: Basic Books, 1990). It provides a unified neurobiological theory that embraces the full reality of perception, memory, learning, language and consciousness as we know it—such a theory as William James dreamed of, but which is only becoming a reality now, in the last decade of this century.

  Israel Rosenfield has provided very original and radical critiques of neurology, and new ways of looking at neurological syndromes. His most recent book is The Strange, Familiar and Forgotten (New York: Knopf, 1992). In one part of this (“The Counterfeit Leg and the Bankruptcy of Classical Neurology”) he devotes considerable attention to the phenomena I describe in A Leg to Stand On.