When the late Oliver Sacks reached North America in the 1960s, he reports in his memoir On The Move, he knew he wouldn't be returning to London and his Orthodox Jewish family anytime soon. He sent home a telegram that read simply, STAYING.
His mother, rarely expressive, was crestfallen. "When you were born," she wrote back, "people congratulated us on what they considered a wonderful family of four sons! Where are you all now? I feel lonely and bereft. Ghosts inhabit this house. When I go into the various rooms I feel overcome with a sense of loss."
Seen through the prism of Dr. Sacks' later case histories, his mother's ghosts aren't simply figurative. Our brains are always "constructing" and "creating" what we call reality, verbs used by one of Dr. Sacks' heroes, the neuroscientist Gerald Edelman. It's especially evident when we are coping with loss. In the adaptive dance of neurons that Edelman's theories describe, the brain is adept at evolving, at compensating, including sometimes by filling in things that aren't always actually there.
Edelman's neural Darwinism saw the brain's networks, Dr. Sacks writes, like "an orchestra … without a conductor, an orchestra which makes its own music" out of experience.
Sometimes that music can be spooky and heart-rending—or comforting. Consider, he said when I visited his office in 2012, the cases of some couples who have lived together for decades.
"The death of the wife or the husband may be followed in thirty percent of cases by visual or auditory hallucinations–faces or voices–and these hallucinations, unlike many others, are often felt as comforting, and may be sought for, and perhaps play a part in the mourning process." Not unlike phantom limbs, or the hallucinations that occur in people who have lost one of their senses, these ghosts are "plugging the hole" during the mourning period, "this sort of terrible existential hole, which is left." During these bereavement or grief hallucinations, they may carry on conversations with their spouses, "in a way which one would think is quite mad, but it may be adaptive and okay."
"I awoke and saw a younger version of my face about two feet away."
The hallucinations that accompany sleep paralysis, for instance, can be very vivid and visceral, auditory, visual and tactile, with the sense of a malignant presence nearby, and a sense of abject terror—what one of Dr. Sacks' colleagues called the "ominous numinous." ("The 'mare' in 'nightmare' originally referred to a demonic woman who suffocated people by lying on their chests," Dr. Sacks wrote in Hallucinations.)
Meanwhile, he added, visions of monsters with outsized heads are common across time and culture. One of the most common forms of hallucination, a Lilliputian hallucination, involves sightings of tiny people. "I think people probably see leprechauns in Ireland and trolls in Norway," he said. "I suspect that many of these strange creatures have if not been engendered been facilitated by hallucination."
Dr. Sacks thought of ghosts, gnomes, aliens, angels, fairies, devils, and sprites as a menagerie of hallucination, of which he chronicled dozens of types, starting with his first book, Migraine. He suffered from migraines, often accompanied by visual hallucinations, since the age of three or four; he would be inspired to write the first draft of the book by a hallucinatory experience on cannabis, amphetamine, and acid, one of a number of drug experiences he describes in Hallucinations.
While he wasn't a believer, Dr. Sacks could appreciate ghosts as manifestations of a surprisingly common phenomenon—born out of what William James, called "exceptional mental states." The phrase became the title of a collection of lectures that James, one of Dr. Sacks' heroes, gave in 1896, about, among other things, epileptic seizures, "demonical possession" and witchcraft. James had visited seances and mediums, which were becoming popular at the time. "I don't think he was any sort of believer, but he was not a scoffer either, and I think what interested him most was the state of mind of the medium and of the people there," Dr. Sacks said.
"I like the word 'exceptional states of mind' because it's not pejorative," he said. "It doesn't say that it's pathological, and one can acknowledge an exceptional state of mind, whereas one may not want to acknowledge a pathological state or be called pathological."
The term "hallucinations" was introduced into English around 1646 by the physician Sir Thomas Browne, who derived it from the Latin word alucinari, meaning to wander in the mind. But it has belonged to the pathological lexicon since the middle 1800s, with a distinctly negative connotation. "It's not too popular with people, whereas terms like apparitions, phantoms and ghosts are more acceptable," Dr. Sacks said.
By the late 19th century in the United States, popular interest in ghosts, telepathy and clairvoyance had reached a crescendo, and some began efforts to understand hallucinatory phenomena scientifically. According to an 1899 survey of 17,000 people in Britain and the United States, close to 12 percent of the population reported having regular hallucinations.
The organization behind that survey, the UK-based Society for Psychical Research, had a crucial emotional connection to the research: many of its early members had lost children. Such a loss "seems against nature," Dr. Sacks said, "and they wanted to know if their child was somehow surviving and if possible how to communicate with the child."
The society's founder, Frederick W.H. Meyers, authored two monumental reports on ghosts, the two-volume Phantasms Of The Living (1886) and Human Personality and Survival After Bodily Death (1903), in which he posits a theory of consciousness that derives from normal psychological phenomena but also from a range of "supernormal" phenomena. Altogether, Dr. Sacks said, the books contain "3,000 pages of wonderful, careful descriptions of apparitions, phantoms, all of which are interpreted in spiritual terms, but all of which need to be reinterpreted, I think in psychological and physical terms."
In these accounts, for instance, spirit sightings were common when people had just woken up. "But we know now," said Dr. Sacks, "that that period after sleep is very fertile for hallucinations—the so called hypnopompic hallucinations, which do get projected outside, can be sometimes terrifying, sometimes very pleasing." Dr. Sacks reported one he had recently had: "I awoke and saw a younger version of my face about two feet away, and it seemed to be looking at me and it was rather moving. And then it vanished after about five seconds."
Dr. Sacks' face hallucination jibes with one of his neurological conditions: In everyday life, he couldn't recognize faces. Face blindness is common in people who have suffered some damage to a particular portion of the back of the right hemisphere, known as the face area or the fusiform face area. But during face hallucinations, brain scans show increased activity in this region, indicating that an area "which is normally employed in recognizing faces will be redeployed for hallucinating faces," he said. Similarly, in blind or partly blind people who have visual hallucinations—including Dr. Sacks himself, who was blind in one eye—brain imaging can show that various parts of its visual apparatus have become hyperactive.
Hallucinations appear so real "precisely because they employ or hijack, whatever word one wants to use, or recoup the sensory areas of the brain, so one is really having sensations or perceptions, but autonomously," he said. Employ, hijack, recoup, redeploy: talking about the workings of the brain can be tricky given how little we know about it actually works. We see spooky things because our brains are spooky things.
"Edgar Allen Poe provides very careful descriptions of his hypnagogic hallucinations, and how he feels they are more extraordinary than imagination, and he had a pretty extraordinary imagination." (A web search for Poe and theory and brain turns up a 2011 "phonoemotional" study of his poems, based on language analysis software designed by the US Navy: "Poe's theory of composition and his sound choices," psychologist Cynthia Whissell writes,"are the outcomes of his emphasis on effect and affect (emotion) rather than cognition, on dream-like creative states, and on semi-conscious right-brain processes rather than alert left- brain ones."
Both Poe and Dr. Sacks were, in their own ways, familiar with the role that narrative and emotion can play in the "creations" of the brain. The "haunting" hallucinations of bereavement and grief (or of longing, or guilt, or severe trauma) might draw heavily on one's memories, and imprint heavily upon them too. Vivid memories—no matter whether they are based on one's own experience or unintentional composites—produce activation of the brain's sensory areas, emotional (limbic) areas, and executive (frontal lobe) areas. Memory, Dr. Sacks said at the end of our interview, was a topic he had hoped to focus on during his later years, while his own memory was still working.
"There is, it seems, no mechanism in the mind or the brain for ensuring the truth, or at least the veridical character, of our recollections," Dr. Sacks wrote in an essay for the New York Review of Books a few months later. When we recall something from memory, our brains are "recreating" or "recategorizing" that event, to use Edelman's terms again. If there is a defect, these assemblages can be mistaken and wild. But even when there isn't, our brains can be unreliable, as reliant on what we've been told as what we've seen or thought ourselves.
Hallucinations appear so real "precisely because they employ or hijack... the sensory areas of the brain, so one is really having sensations or perceptions, but autonomously"
"Frequently, our only truth is narrative truth, the stories we tell each other, and ourselves—the stories we continually recategorize and refine. Such subjectivity is built into the very nature of memory, and follows from its basis and mechanisms in the human brain. The wonder is that aberrations of a gross sort are relatively rare, and that, for the most part, our memories are relatively solid and reliable."
Stories are how we make sense of "the strangeness of the world." For Dr. Sacks, this was the brain's organizing principle and his too, as he tried to make that strange world a little more visible.
"I cannot pretend I am without fear," he wrote in an essay for the Times in February, only a few weeks after learning that a rare form of melanoma had metastasized to his liver. But "I have loved and been loved; I have been given much and I have given something in return; I have read and traveled and thought and written. I have had an intercourse with the world, the special intercourse of writers and readers.
"Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and adventure." His newest book, comprised of that essay and three others, is called Gratitude. Knowing he would be leaving it soon, for good, that was how he felt about the world, monsters and all.
The video above is from the Motherboard archives. All in Your Head is a series that takes a scientific look at all things spooky and scary. Follow along here.