Hallucinations - by Oliver Sacks

Book Review: Hallucinations – by Oliver Sacks, M.D. (Alfred A. Knopf, Kindle Ed, 2012)

This was the last book by the famed neurologist before his death in 2015. Sacks was a very interesting fellow. I heard him interviewed on a few different programs on NPR and found his child-like curiosity interesting. It shows through much of this book as well. Oddly enough, he led quite an interesting life and had many occasions to experience hallucinations, through fateful circumstances, self-induced drug experiments, and neurological experiments. This book is a great broad overview of the subject by one who experienced it from within and but also observed it extensively from without through his many patients and correspondents over the years as well as from study of the literature.

Hallucinations are typically defined as experiencing something through our senses that is not really there, perceptions typically not shared by others. We can visualize, making voluntary images in our mind, as we say it, but involuntary images (or sounds, smells, etc.) would be considered hallucinations. Hallmarks of hallucinations are that they are involuntary, uncontrollable, and they may have spectacular colors or bizarre changing forms. They are often startling. Hallucinations may overlap with misperceptions or illusions. The lines between the three can be difficult to draw sometimes. Brain imaging and monitoring neural activity during hallucinations has allowed us to understand more about them in recent times. They can also help us understand more about brain structures and functions. In the past hallucinations were attributed to “apparitions” or possibly mystical “visions” that could sometimes be meaningful. They have no doubt influenced art. He likes the definition given by William James in his 1890 Principles of Psychology:

“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.”

He states that even though dreams and hallucinations have some overlap and some suggest continuity via hypnagogic and hypnopompic hallucinations, they are quite different and so he will largely exclude dreams from the book. He also spends little time on schizophrenic hallucinations, saying they are of a different quality intermingled with the psychological/mental life of the afflicted. He focuses on “the “organic” psychoses – the transient psychoses sometimes associated with delirium, epilepsy, drug use, and certain medical conditions.”

Sacks notes that many cultures see hallucinations, like dreams, as something to be sought out for meaning and relevant symbolism while in the modern West they are more associated with states of madness. He notes that he has worked with many patients that have vividly shared their experiences over the years and has kept in contact with them, which gave him the data to develop unique perspectives on the subject. 

He begins with a study of hallucinations attributed to Charles Bonnet Syndrome. He stays with some patients as they hallucinate, documenting their accounts. Apparently, with Charles Bonnet Syndrome (CBS) one typically recognizes fairly right away that their hallucinations are not real. They are often as a result of losing one’s eyesight and hallucinations among the blind are fairly common. One woman described them as random and movie-like, sometimes exciting but other times boring. Floating objects are also common. Charles Bonnet described these hallucinations as a result of blindness in the late 1700’s. He himself became partially blind in his later years and experienced some first hand as well. CBS may come and go with different levels of intensity and seeming realness. Some may experience only minor hallucinations of colors and patterns. Sacks notes that although he recognized it in many patients, it seemed less common in the literature before 1990, likely due to misdiagnosis – simply not being recognized. Some people with CBS hallucinate text. Some hallucinate written music, particularly musicians who read music. TV and motion pictures can trigger hallucinations in CBS patients who are not fully blind. Sacks gives several accounts and notes that in CBS cases where vision is preserved there are often disorders of visual perception along with hallucination. 

He mentions the work of Dominic ffytche on researching the neural basis of hallucinations. He and his colleagues tried to categorize hallucinations of various sorts and see what was going on simultaneously in the brain. They noted that hallucinations of faces were associated with activity in parts of the visual cortex associated with facial recognition and hallucinations of color matched activity in the color recognition parts of the visual cortex. Ffytche noted a distinction between visual imagination and hallucination in activating these areas, indicating that hallucinations are more like perceptions than visual imagination. Thus in hallucinations, both the brain and the “mind” have difficulty distinguishing them from reality. CBS hallucinations are typically not associated with memory but perhaps with categorization of objects, or “proto-images” as the general form of objects. Sacks makes the distinction between CBS hallucinations and dreams. Dreams are also psychological phenomena associated with the person while CBS hallucinations occur during waking consciousness and they rarely evoke or convey emotion. They seem to be mainly neuro-visual phenomena. CBS hallucinators characteristically know that their hallucinations are not real even though they are clear and vivid. Sacks notes one case where a blind man with CBS may also be suffering from mild cognitive impairment which makes him suspect the reality of some hallucinations, particularly when alone at night, when he seems to harbor delusions. CBS hallucinations can vary quite a bit. They are generally non-threatening and some may even inspire. It is sometimes apparently like losing the world of sight and gaining a world of hallucination.

Sensory deprivation is the next subject. Sacks notes that the brain needs not only perceptual input to function typically but also perceptual change. Prolonged darkness and other sensory deprivation often is void of such change so that the brain compensates by making its own ‘change.’ Visual monotony can have similar effects such as sailors at sea have noted and even drivers on long road trips. High-altitude pilots are also affected. In the Tibetan Bon tradition of ‘dark retreat’ the practitioners traditionally spend 49 days in total darkness and often have ‘visions’ of ‘lights,’ along with other experiences. This is true also in shamanic traditions that practice prolonged darkness. Effects have been noted also by prisoners in solitary confinement and are known as “prisoner’s cinema.” Immobility due to things like polio and motor system diseases and paralysis could also produce hallucinations. Even having a splint or cast to set a broken bone could trigger tactile distortions or hallucinations of those limbs.

Scientific experiments in sensory deprivation began in the 1950’s. The subjects, college students, typically fell asleep but after they woke they began to crave stimulation. To compensate for their boredom they would play mental games and fantasize but after a while would often experience visual hallucinations that seemed to progress from simple patterns to complex ‘scenes.’ Auditory and tactile hallucinations could also occur. Others reported vast increases in their ability to visualize, especially when researchers asked them to visualize particular things when sensory-deprived. John Zubek was involved with many early experiments and summarized the research in his 1969 book, Sensory Deprivation: Fifteen Years of Research. By the early 1960’s sensory isolation tanks were available where people are suspended in warm water so that the tactile sensations of the body are minimized. Combining these with hallucinogenic drugs could enhance the experience. Simply blindfolding people for prolonged periods also produced hallucinations like colors, trails of light, so-called ‘phosphene images,’ and others. Researchers noted that there were many similarities of the blindfolded participants to those experiencing CBS.

With the advent of brain imaging through functional MRI (fMRI) in the 1990’s we could see what was happening in the brain during hallucinations. Subjects’ visual cortexes became “excitable” very soon after being visually-deprived. Other areas of the brain were also activated. However, when compared to imagining, visualizing, or recalling the hallucinations as opposed to experiencing them, the brain changes were decidedly different.

Marathon and endurance athletes and those participating in rites like vision quests that may include fasting and isolation have also reported hallucinations. Sleep deprivation, dream deprivation, and physical exhaustion can indeed be triggers to hallucination.

  

Some people have olfactory hallucinations although it is apparently notoriously difficult to vividly image smells for most people. He tells the story of a patient who lost his sense of smell (a condition known as anosmia) due to a head injury but later seemed to regain it, albeit only in a hallucinatory form akin to the visual hallucinations of CBS. Like those who have lost their sight, about 10-20% get CBS and it’s the same with anosmia. He tells the story of a Canadian woman who experienced many years of unpleasantly distorted smells after an operation under general anesthesia. Apparently there was no general pattern to it as some things smelled fine but others were severely distorted in negative ways. It is also well known that smells can trigger memories as a sort of “setting” for past experiences. One woman wrote a book about her hallucinated smell of “shit, puke, burning flesh, and rotten eggs. Not to mention smoke, chemicals, urine, and mold.”

Auditory hallucinations are next. He recounts a 1973 ruse where four patients declared falsely that they were hearing voices. Three were diagnosed with schizophrenia and one with manic depression. They were prescribed antipsychotic medicines but did not swallow them. This showed that declaration of auditory hallucinations, more common than realized, resulted in immediate diagnoses of serious mental illness and drug treatment. Although nearly all schizophrenics hear voices not all that hear voices are schizophrenic. Before the 18^th century hearing voices and having visions were generally not considered pathological. They were often considered to be inspiring. Sacks notes his own experience hearing a voice that told him to keep going while trying to descend a mountain with an injured leg and notes that people in danger often hear voices. So too do the bereaved. He also recounts a story of a woman about to commit suicide that heard a voice from within telling her not to do it. Some think that hearing voices is often the result of a temporary inability to distinguish one’s own “inner dialogue” from an external voice. He mentions the controversial and influential book of psychologist Julian Jaynes, The Origin of Consciousness in the Breakdown of the Bicameral Mind, which speculates that all humans experienced auditory hallucinations until about 1000 B.C. when those voices previously attributed to God or gods were realized to be our own inner voices, just us voicing our thoughts apparently. However, this idea is not generally accepted. Some people don’t hear words but just noises. Some people hear songs or music. Hearing loss is associated with hallucinated music (not unlike CBS). Musical hallucinations can vary quite a bit. Some experience them so loud they have a hard time hearing “real” sounds. They may follow a sudden loud noise or tinnitus. Sometimes the music is very vivid and detailed. One violinist actually claimed to hallucinate a piece of music while he was playing an entirely different piece! I once had a musical hallucination of a radio song while having a high fever as a child which I attribute to the fever delirium. Some people experience them continuously. PET and fMRI scans reveal that music activates more brain areas than the other senses which is why, says Sacks, music therapy can be so effective. He does note that musical hallucinations are quite different than visual ones (such as the CBS ones) likely due to the fact that the auditory system is stimulated directly while the visual system is more interpretive. Thus, while the CBS visual hallucinations and auditory hallucinations are similar physiologically, they are different phenomenologically – they are experienced differently. 

  

Parkinson’s disease is another source of hallucinatory experience. Sacks had extensive experience with Parkinson’s patients, most treated with L-Dopa. Aside from post-encephalitic patients who often experience hallucinations right away, many do not get them until months or years of continuous drug treatment. He notes that in 1975 about a quarter of his Parkinson’s patients were having regular hallucinations. Parkinson’s hallucinations vary quite a bit, some being benign and known to be illusory while others may be disturbing or frightening. Paranoia and psychoses may result. Many Parkinson’s patients term their hallucinations as misperceptions rather than hallucinations. Some term them illusions. I think the point is that they do not want to be seen as “crazy.” L-dopa is not considered a hallucinogenic drug since non-Parkinson’s patients prescribed it do not experience hallucinations. Parkinson’s and related disorders of post-encephalitic parkinsonism and Lewy body disease are all neuro-degenerative with hallucinations, cognitive, sleep, and movement disorders. These conditions are far more likely to lead to delusions than CBS. They are associated with abnormalities in the acetylcholine transmitter system that may be aggravated by the L-dopa and similar drugs which keep the movement disorder at bay. People with Parkinson’s may be active and keep their intellect intact for decades so it is often an ongoing treatable condition. There is, however, a more malignant form that involves dementia and hallucinations even without L-dopa. Other forms of dementia including Alzheimer’s and Lewy body disease also often involve hallucinations. Sacks had about 80 patients with post-encephalitic parkinsonism, some that were immobile for decades before L-dopa spurred them back to life so to speak. He thinks the social isolation and immobility added to their hallucinations. 

Humans have sought out altered states for quite a long time. Sacks mentions the incomparable William James and his famous book, Varieties of Religious Experience, where he describes his experiments with nitrous oxide or laughing gas. I have had quite a few experiences with it myself although it has been several decades. James described the opposites of the world merging into a kind of unity, a common description of hallucinogenic drug states. Such drugs are often considered short-cuts to mystical states, however, I suspect that they are less comprehensive than such states arrived at by more gradual and definitive means – but I am not wholly sure. I remember reading Patanjali’s yoga sutras where it was stated that certain “herbs” could also be used to attain various mystical states or samadhis. I do know from many personal experiences that ‘chemical transcendence’ can be quite powerful and ‘paradigm changing.’ I also suspect that it is possible that early human experiments with psychoactive plants may even be partially responsible for the development of consciousness in the form it occurs but this is just a vague hypothesis. Sacks himself did not experiment with psychoactive drugs until age 30 but experiment he did. However, before he did, he had read many books and accounts of such experiments so he kind of knew what to expect. Accounts of opium, hashish, cannabis, the mescaline accounts of Aldous Huxley in his, The Doors of Perception, and accounts of LSD and magic mushrooms are mentioned. He mentions the perceived mingling of the senses and sometimes senses and concepts, known as synesthesia. Many people describe life-changing experience with psychedelic drugs, some good, some not. Heightened senses of color and changes in depth perception and size perception are common. The hallucinatory effects of LSD, mescaline, and other hallucinogens are mostly visual although the other senses and the conceptual effects can also be profound. Sacks was a neurology resident in the early 1960’s in California and such drug experimentation was quite popular there at the time as the mechanisms for the effects of such drugs were just being explored and determined. Neurotransmitter systems were found to be involved with some drugs mimicking some of them, such as serotonin. He started out with pot then LSD and morning glory seeds. 

Then he tried Artane, which is a chemical derivative of belladonna used modestly in the treatment of Parkinson’s, which can be quite dangerous and cause delirium in high doses. At first he was disappointed, having no effects but a dry mouth. It was on a Sunday morning when two of his friends would often show up and they would share breakfast. They indeed did and he talked with them then went in to cook. When he returned they were not there and he then realized they had not been there at all which shocked him. Such effects did not occur with LSD or mescaline. He then hallucinated that his parents came to visit him there on a California beach unannounced from London via helicopter. When he went to greet them they were not there. He then had a conversation and philosophical discussion with a spider.

Sacks did not experiment with drugs during the week when he was working but sought to understand some of the experiences of his neurology patients. He regularly experimented on the weekends. With a mix of amphetamine, LSD, and cannabis he willed himself to “see” the true color of indigo which apparently alludes many. He only saw it once again in his life under the influence of music but no drugs. Once under morning glory seeds a woman friend came to visit him and he rejected her saying she was not real but a replica of his friend. She went away but this concerned her obviously. She recommended he see a therapist since taking hallucinogens in high doses alone every Sunday morning could be seen as a little out of whack. Eventually he did. In 1965 he had three months off and was back in London where his parents, both physicians, were away. Here he first injected morphine. He hallucinated a battle scene from 1400’s England and was shocked when he realized 12 hours had passed in this ‘stupor.’ My own experience with opiates was basically sleep and like his – lost time with dim memories of it. After moving to New York he got in the habit of taking chloral hydrate frequently to help him sleep. One day he began to hallucinate after work which involved slicing human brains which he normally was good at but quite shaky on this day. He coped by writing, by describing his experiences. He made it home, called a friend and she asked him what he had taken – nothing. Then she asked him what he had stopped taking. That was it – he had run out of chloral hydrate and the lack of it was triggering the hallucinations. He was relieved that he was having delirium tremens rather than a schizophrenic episode. The DT hallucinations continued for about 4 days as he sat with his friend before fading away. He would also take amphetamines on Friday nights and maniacally study neurology texts. He would come to experience coming down off of them too which included drowsiness and depression. He would also feel guilty for endangering himself. He read a massive book about migraines while on amphetamines and eventually would write his own book about migraine. After this he never took them again.

  

Migraines are the next topic. Sacks had them all his life. I may have had a couple that I can recall. The migraine “aura” is considered a hallucination, often visual, that often precedes a migraine. Sacks, however, was one of the few that got the aura without the terrible headaches. Sacks’ mother, also a physician, explained migraines to him as a child as she had them too. Migraines affect at least 10% of the population. The main visual effect is known as a scintillating scotoma, scotoma being a blind spot. Intricate patterns, checkerboards, and zig-zags are often seen but there is much variation. Sound and smell hallucinations are also not uncommon. Sacks worked at a migraine clinic and queried every patient he could as it was of great interest to him. “A wave of electrical excitation could track across the cerebral cortex …” [during a migraine]. He wonders if our cultural ‘obsession’ with patterns in art affected our hallucinating of them or vice versa, or if it is some self-organizing activity of visual neurons that lead to it.

Epilepsy is next. Hippocrates called epilepsy the “sacred disease.” However, in modern times in its convulsive form there is much stigma about it. Seizures can take many forms as there are different types of epilepsy with different parts of the brain affected, some hard to watch and control. I have seen dogs and humans do it and it is odd and a bit disturbing seeing beings fall down, shake uncontrollably, slobber, and pee. Damage to parts of the brain can trigger epilepsy. Epilepsy often also has visual symptoms, often hallucinations. Visual flashing of lights can trigger seizures and can even affect non-epileptics with mild seizure-like symptoms. Epileptics can be extremely sensitive to light. Multiplied images, strange mirror reflections as if the image was not the self, vivid colors, olfactory hallucinations, auditory hallucinations of hissing, ringing, rustling, and music have all been reported. Music and marijuana can trigger seizures. The ‘sensation’ of “double-consciousness,” aka. “autoscopy” as in out-of-body experiences has also been reported. This is where one appears to be observing oneself as if from a separate existence. These hallucinations often occur as an “aura” like in migraines, preceding the seizure as in migraines they precede the severe headache. One patient reported dreaming he was having an aura and woke up actually having one. Wilder Penfield attributed pre-seizure hallucinations to reactivated memories but this has been disputed. Memories have been found to be more flexible, more fluid, and far less fixed than early neurologists assumed. 

Epileptics also have “flashbacks” like heavy LSD users and PTSD sufferers occasionally have. There is also a category of seizures known as “ecstatic seizures” that are associated with joy and feelings of well-being, sometimes involving mystical revelations. Dostoevsky was known to describe them as events in his novels. Some epileptics experience “deja vous.” One apparently had a vision that Christ ordered him to kill his wife then himself which he did but he survived his self-stabbing. Some suggest that Joan of Arc had temporal lobe epilepsy and that her “visions” were pre-seizure auras. The age of onset and length of the visions support this. Sacks notes that such visions may have effects on social history as hers exemplify. He wonders what the relationship between pre-seizure auras and religion could be – a specific part of the brain associated with religious thinking or some other factor. Although religious revelations occur only in a small number of epileptics they can even happen in the skeptical and non-religious. One account involves seizures that led to religious revelations and conversion but subsequent seizures leading to a non-religious and equally fervent conversion to atheism. 

Damage to the occipital lobe via stroke and other damage to the visual system of the brain can result in hallucinations – often as in CBS, recognized right away to be hallucinations. Often these hallucinations occur in just one-half of the visual field and are called hemianopia. In some people they are continuous. The imagery can be more vivid and detailed than normal vision. One patient who experienced temporary hallucinations from a stroke described them as going from simple and still images to complex moving ones than back to simple before fading away – as if a wave moved through the brain. One patient experienced complete loss of vision in one half of the visual field and apparently his brain filled in the rest based on past experience. Indeed this is apparently an aspect of how the brain-vision system works in all of us. There are also cases where patients are half-blind as in hemianopia but consistently insist that they are not – that if they bump into something it had to have been put in front of them. Perhaps the brain “fill-in” is too good and seamless. Some are completely blind with this Anton’s syndrome and yet insist that they can see just fine! Another case involved a man who had gone blind but was also an alcoholic and insisted that on a couple occasions while drunk his vision had returned! From his descriptions which some were plausible but many wrong it seems his returned vision may have been hallucination that somehow partially mimicked the real based on expectation. 

As a medical student in London, Sacks saw many patients with delirium, from infections with high fevers, or kidney and liver failure, lung diseases, diabetes, or from medications. Delirium usually indicates a medical problem rather than a neurological one. He observed one patient ‘talking nonsense’ in a delirium before he died. Sacks noted that the patient was mixing reality and fantasy, somewhat like a dream. When Sacks talked to him and let him know he was listening the patient became more coherent. I observed this kind of nonsensical yet interesting talk in my 95 year-old grandmother just before her death. Indeed I think it is fairly common among the dying. Children with fever often experience delirium as I did in a mild way. One description was that the child was changing size, growing and shrinking. Descriptions of swelling of one’s body image are common. Waxing and waning auditory hallucinations occur. Mine was auditory, a song from the radio in a sort of transistorized form. I still remember the song and I may find it on youtube and listen to see if it brings back any weird memories. I just did – no great effect! (Incidentally, the song was Walking in Rhythm by the Blackbyrds). Some consider delirium to be a source of revelation as in psychedelic drugs. Opium and high levels of alcohol or withdrawal from them can also cause delirium. Temporary paranoid delusions can occur. Sacks experienced “elaborate narrative dreams with extremely brilliant colors …” while visiting Brazil in 1996. He had gastroenteritis with some fever and assumed his dreams were a result of this, perhaps compounded by his excitement at visiting the Amazon. The dreams were continuous, sometimes drifted into his initial waking state, and exhausted him from sleep deprivation. This was highly unusual for him as he did not dream like this. His analyst asked him about medications then he realized he had been taking Larium, an anti-malaria drug, standard for visiting the Amazon. A glance at a PDR and consultation with a doctor friend confirmed this effect which lasted a while after before it faded. One of Sacks’ Parkinson’s patients was amiss when he claimed Sacks told him (via audio) to grab his hat and coat, go to the roof of the hospital, and jump off. Sacks told him to look for him to see if he could be seen if it happened again. The patient said it wouldn’t work and sure enough when it happened again the hallucinated Sacks voice told him not to turn around because he was really there. Fortunately, the patient didn’t jump and recovered from his hallucinations.

Hypnagogic imagery and hypnopompic hallucinations are next examined. Hypnagogic imagery occurs near the onset of sleep and hypnopompic near the conclusion of sleep. Many of us have had hypnagogic imagery which may include kaleidoscopic scenery, vividly detailed imagery, and series of changing, morphing images. When I was a cigarette smoker long ago I would sometimes smoke one before bed and I remember having occasional odd hallucinations of echoes, images of changing size, audio changing volume, etc. I am pretty sure it was due to the hallucinatory effects of nicotine but it may have been combined in some way to hypnagogic imagery. Andreas Mavromatis studied hypnagogic imagery extensively. He noted that visions of faces are common. Facial hallucinations involve the facial recognition area of the visual cortex, neuroscientists have determined with fMRI. Most hypnagogic imagery is considered to be generated from within with eyes closed sdiffers from hallucinations in some respects but it shares the involuntary and uncontrollable nature of hallucinations. It can be dream-like too. Some neuroscientists consider it to be associated with the brain “idling” down before sleep.

Hypnopompic hallucinations, often seen with eyes open can be quite different than hypnagogic ones seen with eyes closed. They are also less common, but frequent in some people. They are far more likely to be mistaken for something real. They can be terrifying or amusing. The feeling of a “presence” is a common type. They may be mingled or mistaken for dreams or “false awakenings” from dreams but are apparently quite distinct. Early researchers sometimes considered them fragments of dreams that remained upon awakening. 

The next chapter explores narcolepsy and sleep paralysis. So-called ‘night hags’ usually refer to an interpretation of ‘sleep paralysis’ where one appears to wake unable to move (a type of body paralysis or astasia which is a sudden loss of muscular strength – associated with REM state). Such states often occur with disturbing scenes or presences (such as the night hag). It is a fairly common occurrence (I have had several over the years) among the population and some are predisposed to it. Apparently, it is very common with those that experience narcolepsy. Narcolepsy is associated with the “wakefulness” hormones called olexins that are secreted from the hypothalamus. A related condition is ‘cataplexy’ which is the complete loss of muscle tone with emotion or laughter. Sacks attended Narcolepsy Network meetings to hear stories and accounts from those who suffer from it. It often goes undiagnosed, especially in childhood and the hallucinations can be mistaken for schizophrenia or even paranormal activity. Nodding off among the elderly may be a more common milder symptom akin to it. Auditory and tactile hallucinations may accompany visual ones in narcolepsy and sleep paralysis. Since REM sleep is associated with muscle paralysis it was found that sleep paralysis sufferers remain in the REM state while having their hallucinations. Among the Hmong people from Laos there is a cultural belief that sleep paralysis can result in death. Many as refugees were not able to perform the rites to alleviate it with great specificity and so the fear grew. There are a couple hundred of unexplained nocturnal deaths among Hmong refugees which suggests that death by maladies like heart attack triggered by fear could have been the cause. This is possibly a ‘nocebo’ effect based on expectation that triggered physiological reactions can result in death.

Hallucinations triggered by emotional trauma and grief are also fairly common, particularly involving dead loved ones and relatives. Sacks lumps these into the topic of “haunted mind.” Most often people hear the voices of their dead relatives. Habit and expectation may play a role as hallucinations of dead spouses are the most common. Sacks recounts his own recent experience of tripping over some books, falling, and breaking his hip where he vividly re-experienced the details of it in slow motion as he had at the time, for a few weeks after it happened. He heard and felt the crunching of the breaking bone. He reckoned this a sort of trauma-induced hallucination. He considered it mild compared to what some sufferers of PTSD experience. PTSD sufferers experience ‘flashbacks’ of traumatic experiences that may be intense and delusional. Victims of rape, sexual assault, torture, disasters, accidents, and war combat are most susceptible. Strangely those affected by natural disasters are less susceptible to it which suggests having something done by another person against one’s will is of a different category than a so-called “act of God” for many. Early on these were thought to be neuroses, all in the mind, but changing of the brain is now well-confirmed. Even mild concussions and other brain trauma can also change the brain and lead to cognitive impairment. So PTSD is definitely biological as well as psychological in many cases. In the past it had been attributed to ‘dissociation’ and it may still be, but a form of dissociation that is much more severe, one that can change the brain and its memories. In fact, exploiting the flexibility and plasticity of memory is one way of treating severe PTSD. Flashbacks may be traumatic memories not normally accessible but triggered by sensory and social situations. The memories may be such that they are not seen as memories but as reliving the experience itself. Severe stress can also lead to trance-like states that can trigger hallucinations, usually termed ‘hysteria.’ He also mentions mystical and ‘spiritual’ states that may involve hallucinations. Most religious, mystical, shamanic, and mythical literature is full of accounts and analyses of such states and visions. The power of suggestion can also be a factor in many states that may involve hallucinations or visions – since they are often experienced with the cultural motifs to which one is accustomed – but by no means always. He mentions the imaginary companions of children which may seem real to them. Sacks attended many at their deaths and noted that hallucinations often accompany people who see their death as immediately impending.

Doppelgangers and out-of-body experiences can be seen as hallucinating oneself. Seizures, migraines, sleep paralysis, near-death experiences, lucid dreams, and other phenomena may involve so-called OBEs of possibly varying sorts. Sacks goes through the characteristics of these experiences which have been extensively dealt with in several comprehensive studies and books on the subject. Bright lights, tunnels, and communication with the dead or other disembodied beings can accompany these experiences. Some researchers have proposed physiological and/or neurological explanations, others more psychological ones. Some people have experienced doppelgangers in the context of normal waking consciousness, most often with them being a mirror images of oneself with the sides reversed as in a reflection. It is now thought that a third of these cases are associated with schizophrenia. Most experiences are benign but some may be harmful and delusional mostly in the schizophrenic cases. In folklore doppelgangers are often considered portents of death. All our lives we are “embodied” so that becoming “disembodied” is both unusual/odd/disconcerting and an indication that something is amiss. Of course, shamans, magicians, witches, and others are said to be able to become disembodied and to practice this as an ability being part of their craft. Thus there are ‘practices’ to develop the ability to become disembodied. 

Sensory ‘delusions’ as shadows, phantoms, or ghosts are common among many people and in lore throughout the world. Among accident victims and amputees there is the common phenomenon of the “phantom limb.” This is the sensation of feeling the limb to be present after it has been removed, in many cases long after and for the rest of one’s life. Phantom hands were the least likely to disappear after a long time. Phantom limbs are hallucinations but there are of a different character since they are based on past neurological habits and wiring. Initially most phantom limbs can be ‘moved’ but often become immobile or paralyzed with the patient becoming unable to ‘will’ the movement as before. The hallucinated paralysis is considered to be a ‘learned’ paralysis. Phantom limbs occur in virtually all amputees, and typically immediately, as opposed to hallucinated sight or hearing in the blind and deaf which comes later in 10-20% of patients. This suggests that the material for hallucinations comes from past perceptions and sensations. The phantom limb effect is used to good measure in prosthetic limbs which can be animated by the willing of the phantom limb. In a sense it gives life to a hallucination and many have benefitted. Some patients report a phantom limb to be disturbing at night when the prosthetic device is off but relieved when they put it on in the morning and the phantom is assumed by the artificial limb. Unfortunately the perception of phantom limbs change over time, often to contorted, painful, shrunken, or expanded forms. A hand may be perceived as permanently clenched or there may be a sense of permanent muscle spasms. One of Sacks’ patients, a quadriplegic, paralyzed from the neck down, reported a full phantom body. This suggests that body image is not fixed. Many of us have experienced partial distorted senses of body image with dental anesthesia when parts of our mouths are numbed by local anesthetics. One MS patient described the sensation of an extra limb, an extra right arm. Neurologists are currently working on ways to “unfreeze” painful, contorted, and unwillable phantom limbs. He mentions the work of V.S Ramachandran in this regard. He achieved good results by providing a simple optical illusion of the limb moving so that the ‘learned paralysis’ could be relearned into movement. Virtual reality systems have also been used to successfully reduce some of the pain of phantom limbs and to get some of the ability to ‘will’ them to return. There is another phenomenon known as “reflex paralysis” which Sacks experienced in his mountaineering accident when he ruptured the quadriceps tendon in his left leg. He experienced the loss of ‘limb image’ when in a cast after surgery for about two weeks. He suspects that one of Ramachandran’s ‘mirror box’ optical illusions could have relieved that at the time. There is something similar to reflex paralysis called body-integrity identity disorder where patients feel a sense, often from childhood on, that a limb or part of a limb is foreign to them, not theirs. Some have a compelling desire to have the limb amputated. Sophisticated brain imaging has also helped in understanding phantom limbs and the neural basis of embodiment. One patient, after having a brain tumor removed had the sensation of a foreign limb in his bed with him and threw himself off the bed to try and remove it. Stroke patients may lose feeling in one side of their body and some may come to consider that side not to be part of them but to be someone us. The sense of a presence, or of someone watching you when you are alone may be a similar kind of body image distortion. Such ‘presences’ are more common when one is in a state of anxiety. Electrical stimulation of the brain was also found to induce such a presence of a ‘shadow-person’ among one epileptic patient. William James wrote about ‘sensed presence’ in his Varieties of Religious Experience. He described such experiences from accounts as deeply felt, not necessary ‘religious’ but that could be interpreted as such by one with a predisposition to religious belief. Finally, Sacks makes the suggestion:

“… the primal, animal sense of “the other,” which may have evolved for the detection of threat, can take on a lofty, even transcendent function in human beings, as a biological basis for religious passion and conviction, where the “other,” the “presence,” becomes the person of God.”

Awesome book. Rest in Peace Mr. Sacks.