Oliver Sacks on drugs
300pp. Picador. £18.99.
978 1 4472 0825 9
U ntil the French psychiatrist Jean-Étienne Dominique Esquirol gave them their current name, hallucinations – seeing or hearing things that are not there – were called “apparitions”. This captures their profoundly disturbing nature, an eeriness which is not fully reflected in the definition Oliver Sacks quotes from William James’s The Principle of Psychology (1890):
“An hallucination is a strictly sensational form of consciousness, as good and true a sensation as if there were a real object there. The object happens to be not there, that is all.”
Unlike mental images, hallucinations do not remain obediently inside your head. They are outside of your control – projected into the world that surrounds you – which reinforces their compelling reality. They have a life of their own, breaking into your chosen biography rather than belonging to it.
Their power to terrify may be in part due to their content, but even the most benign hallucination is deeply unsettling precisely because, as Sacks says, there is no “consensual validation”. Nobody else can see, hear, feel, smell or taste what you are experiencing. To be in the grip of such incorrigibly private experiences, adrift in a world populated with items that others cannot confirm, is to be sequestrated in the most profound solitude. Even before we speak, we will point out things that we see and desperately want to share with others. Joint attention to items that we all agree are before us is the basis of a common human world. The involuntary perceptual dissidence of the one who hallucinates reminds us how frail and transient is our occupancy of this world; and how, even when you and I are side by side in the sunlight, each of us may be sealed in the privacy of our minds.
To be in the grip of such incorrigibly private experiences is to be sequestrated in the most profound solitude
It is scarcely surprising, therefore, that the isolation hallucinations impose on those who suffer from them is compounded by a reluctance to speak of them. And yet they are extremely common, as Sacks points out in his opening chapter when he talks about the “silent multitudes” of visual images that may fill the gathering darkness when eyesight starts to fail. The Charles Bonnet syndrome – named after the polymath physician who first described it in the eighteenth century – is marked by extraordinarily complex and variable images. This is how Rosalie, a blind ninety-year-old woman in a nursing home, described what she “saw”:
“People in Eastern dress! . . . In drapes, walking up and down stairs . . . a man who turns towards me and smiles, but he has huge teeth on one side of his mouth. Animals, too. I see this scene with a wide building, and it is snowing – a soft snow, it is swirling. I see this horse (not a pretty horse, a drudgery horse) with a harness, dragging snow away . . . . But it keeps switching . . . . I see a lot of children walking up and down stairs.”
She is greatly relieved when Sacks tells her that “her hallucinations represented a recognised condition, one that even had a name”. She was keen for him to tell the nurses that she had Charles Bonnet syndrome.
There is an intuitive explanation of why perceptual loss – as in blindness and in experimental sensory deprivation tanks – should be associated with hallucinations: that nature, the brain, the mind, abhors a vacuum. This, however, does not explain why, in Rosalie’s case, the symptoms began only many years after she had gone blind. Nor does it account for the richness of her hallucinations. The general propensity to hallucinate, however, is unsurprising, given the complexity of the processes – cerebral and mental – that underpin ordinary perception and the extent to which the world we experience around us is a construct that goes far beyond the raw material of sensation. It is not surprising that they can be induced in so many different ways. Sacks’s masterly catalogue raisonné of these coinages of the mind surveys the effect of drugs (prescribed and recreational), migraine (where there are transient alterations of the blood flow to parts of the brain), epilepsy (in which there are massive spontaneous neural discharges), delirium (associated with fevers and toxins of various sorts), sleep (normal and abnormal), disturbances of body image (following loss of a limb or a stroke), near-death experiences (after cardiac arrest), and direct stimulation of the brain (in waking subjects undergoing epilepsy surgery). In doing so, he draws on his previous writing, and in some respects this could be seen as the summa neurologica of this supreme observer of the phenomenology of neurological disease.
His interest in the subjective experience, as opposed to the objective account, of neurological disease that normally dominates textbook descriptions, was triggered by a lifelong experience of migraine. His first attack, when he was three or four years old, took the form of a shimmering light, which expanded to an enormous arc stretching from the ground to the sky and underwent a series of brilliant transformations before his left visual field emptied. He was lucky that he had a mother who recognized what this was – a prodromal migrainous aura which in his case was not succeeded by a headache – and was able to reassure him that he was not going either blind or mad. Many years later, he immersed himself in Edward Liveing’s nineteenth-century treatise on “Megrim” and other “Nerve-Storms” which, aided by the amphetamines he was then taking, induced a state of ecstasy in which he saw “migraine shining like an archipelago of stars”.
Sacks describes the migrainous auras, as he does other hallucinations, with the loving attention of a naturalist or a collector. He looks beyond the standard fare of the medical literature on migraine which tends to focus on diagnostic signs, such as zigzag lines (“fortification spectra”) to more exotic visual phenomena such as that experienced by a patient who reported “a fly’s eye made of millions of light blue Mickey Mouses [sic]”. These and other effects show, he argues, “what a colossal and complicated achievement normal vision is” – where a world is constructed in which “colour and movement and size and form and stability are all seamlessly meshed and integrated”. The aura of migraine, like that associated with certain forms of epilepsy, was, as the nineteenth-century astronomer George Airey said, “a sort of photograph” of the brain in action.
The results of Sacks’s explorations were occasionally ecstatic, sometimes merely strange and often terrifying
In the 1960s, Sacks extended his neurophenomenological explorations by taking a variety of recreational drugs; not only amphetamines but also pot and, of course, LSD. The results were occasionally ecstatic, sometimes merely strange and often terrifying. Conversations with a friendly spider – with whom, after an opening exchange of pleasantries, he discussed whether Bertrand Russell had irreversibly damaged Frege’s system of thought with his famous paradox – and studying key moments from the battle of Agincourt enacted on his dressing gown sleeve, were not atypical episodes in the pharmacological dramas unfolding in his head. He fought off panic by carefully transcribing the “craziness” inside himself, writing “for dear life” as “wave after wave of hallucination” rolled over him. These were not quite as crazy as the experience of the student Daniel Breslaw, a subject in a formal study of LSD, who, entering an elevator, passed “a floor every hundred years” and, when back in his room, swam “through the remaining centuries of the day. Every five eons or so a nurse arrives (in the aspect of a cougar, a differential equation, or a clock radio) and takes my blood pressure”. As if this were not enough, Breslaw experienced synaesthesia, or a fusion between the senses, reporting such gems as “the smell of a low B flat, the sound of green”.
The varieties of hallucinations are protean. While vision predominates, hearing, smell, taste, touch, memory, altered body image and strange emotions seeking an object, often figure. Phantosmia (hallucinations of smell), analogous to the Charles Bonnet syndrome, may occur in people who have lost this sense. Auditory hallucinations, in addition to those bothersome, frightening voices, take many forms. The unremitting mental junk of tinnitus is a huge source of suffering, but musical hallucinations following damage to the brain may be just as distressing. Imagine hearing Bing Crosby, friends and orchestra singing “White Christmas” for days on end: a thousand times worse than the musical phrases or “earworms” that stick like limpets to the normal mind. Tactile hallucinations can be compelling, as in the case of one of Sacks’s subjects on drug treatment for Parkinson’s disease. The surfaces of objects seemed to be covered by a film of peach fuzz, cotton candy, or spider’s webs, and the film sometimes became very “lush” as if the items were submerged under a pile of “stuff”. Hallucinations can sometimes be multisensory. When ninety-year-old Rosalie became ill and thought she was dying, she had visions of her mother and heard her welcoming her into heaven. These were completely different from her usual hallucinations: as well as being multisensory, “they were personal, addressed to her, and steeped in warmth and tenderness”. The most “respectable” hallucinations are those we are all prone to on a daily or more usually nightly basis – associated with sleep. They, too, however, are not without their terrors, as Sacks describes. Hypnagogic hallucinations, seen on the threshold of sleep, may take the form of faces or presences charged with malign intent. And hypnopompic hallucinations, which occur on waking, are often seen with open eyes, the terrified gaze populating the darkness with evil faces, spiders, snakes and devils. For some people, “night hags”, sometimes associated with abnormal propensity to dream sleep – narcolepsy – may interfere with their waking life. Occasionally they become a dark secret they dare not share with others.
Hallucinations is so rich and so respectfully attentive to the particulars of neurological illnesses, and the people who have them, that it is disappointing that it scarcely touches on the philosophical questions raised by its subject. This omission is particularly striking in Sacks’s discussion of epileptic seizures (where he surprisingly relies on outdated terms such as “grand mal”), in which part of the brain has massive synchronized, spontaneous activity. While many of the epileptic manifestations he discusses are not strictly hallucinations, they are nonetheless of the greatest interest. They include déjà vu, out-of-body experiences, and even episodes of ecstasy that some patients have interpreted as revelations of the presence of God, leading them to religious conversion. The rough correlation between the brain area affected by the abnormal activity (more precisely located by electro-encephalography and functional magnetic resonance brain scans) and the kinds of experiences patients have, has misled some writers into imagining that the experiences are identical with the neural activity (or even, in extreme cases, that religious beliefs are epileptic phenomena). This neuralization of consciousness – according to which brain activity is not only a necessary but also a sufficient condition of consciousness and indeed is identical with it – has seemed to some to be justified by the famous observations of Wilder Penfield, discussed by Sacks.
Penfield, a Canadian neurosurgeon, pioneered surgical excision of epileptic foci for uncontrolled seizures. He electrically stimulated the brains of his waking patients during the operation in order to locate vital structures that he should avoid. Several of his patients had complex, spontaneous memories triggered by stimulation, and this observation has led some to argue that memories and other experiences are identical with activity in certain brain circuits. This does not of course follow. First of all, the patients were already awake – stimulation of the same pathways would not have activated memories in comatose patients – and second, memories would not have been activated by direct neural stimulation had the relevant events not already been experienced by the normal route of a person acquiring them in the context of everyday life, in which, unlike hallucinations, they are part of a boundless common world of the meanings we share with others.
Close by this is another avenue Sacks could perhaps have explored: the organization of hallucinations – as in the case of spiders who talk analytical philosophy – which would be astonishing if they were purely coinages of an activated brain freewheeling independently of an extra-cranial reality. It is evident that they involve a top-down shaping – and sense-making – activity of the mind, which eludes the kinds of understanding available to currently fashionable reductionist accounts of the conscious mind as identical with neural activity, seen ultimately as the effects in a material brain wired into its environment of causative material events impinging on sense endings.
Hallucinations have long interested philosophers of perception. They are invoked to challenge what is called “naive realism”. That what we see is not always out there, reminds us that our sense of what is out there is mediated – at the very least by our senses. This has raised questions of whether what is there exists independently of our senses. The “Argument from Illusion (or Hallucination)” leads to the view that even items we regard as the basic furniture of everyday life – material objects – are merely constructs of sense experience. These venerable views are no longer mainstream. As Gilbert Ryle said, illusions cannot undermine the truth of other experiences because “there can be false coins only where there are coins made of the proper materials by the proper authorities”. And, more recently, disjunctivist philosophers have reasserted what the rest of us suspected, that veridical perceptions and hallucinations – howsoever similar – are not the same kinds of mental entities. Even so, hallucinations are a deeply disturbing reminder of how what we take for reality is under-determined by the sense experiences on which our taking is based. And the puzzle of the relationship between our perceptions, the objects we individually perceive, and what we all agree is there, remains.
The richness, complexity and infinite variety of hallucinations are the underside of the richness, complexity and variety of “ordinary” perception. The fact that they are experienced as invaders from without is a reminder of the extent to which our sense experience normally coheres at and across times. This is extraordinary, not least because the items that are brought together in and between moments of consciousness are also kept tidily apart, so that I can experience items in the visual field separately, sounds distinctly from sights, emotions and thoughts and memories from the immediate data of sensation, and can attend separately to, and report, the colour, size and location of an object while experiencing them all at once. Hallucinations betray their nature by not fitting into the seamless fabric of experience and meaning unfolding over time until they become so insistent that they have a subjective reality comparable to that of the objects that others can also see.
Though the philosophically fascinating issues are largely bypassed by Oliver Sacks, Hallucinations is nonetheless a superb synthesis of the literature on these arresting, disturbing and sometimes terrifying phenomena, and a profound work of humanity – reaching out to all those who are prone to hallucinations – in short to all of us. I hope it is widely read so that many people will take comfort in knowing that, in undergoing these most solitary of experiences, they are not alone.
Raymond Tallis is Emeritus Professor of Geriatric Medicine at the University of Manchester. His books include Aping Mankind: Neuromania, Darwinitis and the misrepresentation of humanity, 2011, In Defence of Wonder and Other Philosophical Reflections, 2012, and Reflections of a Metaphysical Flaneur, forthcoming.
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