Most of the examples of hallucinations in Oliver Sacks’s graceful and informative new book do not have the transparent motivations of my episode in the Freud museum. Indeed, most of his examples don’t seem “motivated” at all; they have causes rather than meanings. That is, most of the occurrences seem to be products of neurological misfirings that can be traced to disease, drugs or various changes in neurochemistry. With some important exceptions, hallucinations don’t seem to reveal desires or intentions — the kinds of things that create meaning; they do reflect workings of the brain that cause us to see or hear things that are not really there. Parkinsonian disorders, epilepsy, Charles Bonnet syndrome, migraines and narcolepsy — drawing upon descriptions of these and other conditions by patients and doctors, Sacks explores the surprising ways in which our brains call up simulated realities that are almost indistinguishable from normal perceptions.
As is usually the case with the good doctor Sacks, we are prescribed no overarching theory or even a central argument to unite his various observations. Instead, we are the beneficiaries of his keen observational sense, deep clinical practice and wide-ranging reading in the history of neurology. This doctor cares deeply about his patients’ experiences — about their lives, not just about their diseases. Through his accounts we can imagine what it is like to find that our perceptions don’t hook on to reality — that our brains are constructing a world that nobody else can see, hear or touch.
Sacks has been fascinated by neurology since his student days (he is now almost 80), and he recounts his personal experiences with neurochemistry. He started experimenting with LSD in the 1950s, and when he was a medical resident living in Southern California’s Topanga Canyon in the 1960s, his drug use combined recreation with investigation. Opiates later upped the ante, and Sacks describes his interest and pleasure in altered states of consciousness. He recalls his hallucinations that drew heavily onFroissart and Shakespeare with neither pride nor shame. His perceptions weren’t based in reality, but could he still learn from them?
Sacks has long been an avid reader of the history of medicine, and he beautifully describes his intense, amphetamine-inflected readings of such 19th-century medical texts as the English physician Edward Liveing’s work on migraines. Drugs made reading seem more powerful, but as he came down from his high, Sacks realized that while under the influence of drugs he would never be able to write with the kind of sustained attention and care evident in the texts he admired. His epiphany was that he should follow his creative muse not through more powerful hallucinations but through the work of medicine and writing. “The joy I got from doing this was real — infinitely more substantial than the vapid mania of amphetamines.”
Over the past decades we have learned much more about how we see and hear with our brains — not just with our eyes and ears. Sacks describes how neurosurgeon Wilder Penfield was able to induce “experiential seizures” by tracking electrodes over the surface of an exposed temporal cortex during surgery. His patients seemed to experience vivid flashbacks, as if the electrical charge had catalyzed a memory into a perception. Vivid though they were, these recollections seemed to lack personal significance. More recent work has explored how the brain creates networks of recollection that allow us to access memories, even as we reshape the past while bringing it into consciousness.
Some hallucinations, Sacks writes, do seem connected to highly significant, emotionally charged memories. When deep in grief, for example, we are more likely to perceive our loved one, even though we know that person has died. Bereavement “causes a sudden hole in one’s life,” and a hallucination evinces a “painful longing for reality to be otherwise.”
At the end of “Hallucinations,” Sacks returns to phantom limbs, a subject he wrote about at length in “A Leg to Stand On.” Amputees report pain in limbs they no longer physically possess, the brain seeming to retain an image of the body that trumps physical reality. Physicians today help patients learn to use their phantom limbs, fitting them into prostheses so that they can use their hallucination of a body part to maneuver what no longer seems like an artificial limb.
Turning a phantom limb from something strange and painful into something one integrates with one’s sense of self is a medical and human triumph. Sacks has turned hallucinations from something bizarre and frightening into something that seems part of what it means to be a person. His book, too, is a medical and human triumph.
Michael S. Roth
is the president of Wesleyan University and the author of “Memory, Trauma, and History: Essays on Living With the Past.”