We Are Our Brains

by D. F. Swaab

  When your brain manufactures information on the spot where it’s normally processed, it’s interpreted as if it had entered from outside, via the normal route. If the auditory cortex (fig. 22), for example, stops receiving the information it normally gets from the ears, it starts to work overtime, producing something that that part of the brain normally processes: music. You would therefore expect the maddening tunes to disappear if you stimulated the auditory cortex. However, it wasn’t easy for the man I met to find a doctor prepared to try that. In the end, he was treated by Dirk de Ridder of Antwerp. A short test involving electromagnetic stimulation of the auditory cortex caused his tinnitus to vanish, only to return gradually after a few days. He then splurged on a pair of €4,000 Varibel “hearing glasses” developed by Delft University of Technology, which greatly improved his hearing and reduced his tinnitus. This shows that the brain stops producing old information once it receives fresh input again, and it makes no difference whether the input is meaningful (the hearing glasses) or has no information content (the electromagnetic stimulation).

  Charles Bonnet syndrome is another phenomenon wherein the brain manufactures information to compensate for a lack of input. The condition provokes colorful visual hallucinations in individuals with impaired sight, typically older people with cataracts, glaucoma, or retinal bleeding. The hallucinations—often complex, vivid images of people—tend to occur in dim light and quiet surroundings. Sufferers of Charles Bonnet syndrome are aware that their hallucinations aren’t real and find that they usually disappear if they shut their eyes. An eighty-three-year-old woman who had played an active role in the Dutch resistance during the Second World War and who had become practically blind due to glaucoma confided anxiously to her daughter that whenever she blinked her eyes she saw swastikas.

  In the case of Charles Bonnet syndrome, the visual cortex (fig. 22) receives insufficient information from the eyes and starts to produce its own pictures. A similar phenomenon occurs in the case of memory loss. People who suffer from Korsakoff’s syndrome, a dementia that results from alcohol abuse, produce fake memories of events that never took place, known as confabulations. Phantom sensations following amputation appear to be based on the same principle. Lacking customary input from a limb, the brain “makes up” the presence of a missing arm or leg. Hallucinations can also be a sign of neurodegenerative diseases like Lewy body dementia, which often involves impaired visual perception, and Alzheimer’s disease and Parkinson’s disease.

  In schizophrenia, input to areas of the cerebral cortex is also reduced, so the hallucinations it provokes could be caused by the same mechanism. Depending on the area of the cortex that is overactive, schizophrenia patients see or hear things that aren’t there. A group headed by René Kahn in Utrecht has indeed shown, in a series of pioneering experiments, that electromagnetic stimulation of the brain reduces hallucinations in schizophrenia patients. Conversely, isolation cells, in which these patients tend to be confined during acute stages of the disease, diminish brain input even further and can thus make their symptoms much worse.

  Mountaineers, especially when alone, sometimes have very vivid hallucinations (hearing voices, seeing people, or having out-of-body experiences) or are overcome by fear. So it’s interesting that the revelations received by the leaders of the world’s three main religions were preceded by a period of isolation in the mountains. On two occasions, Moses received the Ten Commandments from the Lord on Mount Sinai. On the second occasion he spent “forty days and forty nights” there alone “without eating bread or drinking water.” When Jesus took the disciples Peter, John, and James up a mountain to pray, they had a vision of Moses and Elijah. The Prophet Muhammad saw the Archangel Gabriel during his lonely vigil on Mount Hira. These experiences involved seeing bright lights, hearing voices, and experiencing fear, just as in the case of mountaineers. When the brain is very isolated it starts to use stored experiences and thoughts to manufacture things—sometimes even new religions.

  OTHER HALLUCINATIONS

  When we remember we are all mad, the mysteries disappear and life stands explained.

  Mark Twain (1835–1910)

  Delirium

  Hallucinations are by no means confined to schizophrenia. They are most common in cases of delirium. In the Netherlands, around one hundred thousand patients a year experience delirium. Most of them are elderly people who have been operated on under general anesthesia (because of a broken hip, for instance). For an old brain, an anesthetic is like a dose of near-lethal poison. In intensive care, up to 80 percent of patients experience delirium. Delirium can also result if the brain’s functioning is impaired by pneumonia, dehydration, medication, drugs, or malnourishment. In older people it can even be caused by a simple urinary infection. Then there’s the famous delirium tremens, which isn’t solely caused by alcohol poisoning—it can result from alcohol deprivation. Brain damage due to lack of oxygen, low blood sugar, or an infarct can also induce delirium.

  Delirious patients are extremely confused. They are often restless, have memory problems, and are aggressive, noisy, and sometimes hyperactive to the point of falling out of bed and breaking something, ending up in even worse shape than they were before. But there’s also a peaceful type or phase of delirium in which patients simply lie in bed apathetically, staring blankly. Their consciousness is impaired. They don’t know where they are or sometimes even who they are. They can’t think straight or concentrate. The condition sometimes resembles dementia, but delirium strikes all of a sudden, while the onset of dementia is gradual. Delirious patients will hallucinate, often seeing creepy crawlies everywhere. Some have been known to refuse food or drink because it appeared to be covered with ants. One patient saw beetles coming out of the ceiling. Feverish children can have visions of cartoon characters (one little girl reported seeing Donald Duck riding her father’s bicycle along her bedroom wall). The hallucinations and delusions are often frightening. One patient, a Holocaust survivor, thought that he was being sent back to a concentration camp and was terrified of his doctors and nurses, believing that they had come to get him. In his desperate attempts to escape, he tore his drip out of his arm and then the tube through which he was being fed—a dangerous thing to do, because if the food had gotten into his lungs he could have developed pneumonia. A female patient thought that she had been tied up and raped in the hospital. An old friend of mine, refusing to believe that his operation was over, asked the doctor why on earth he had visited him in the middle of the night. He went on to reprimand the doctor for not having the decency, during this nighttime visit, to answer his queries about the results of his blood test. My friend believed that he had then gone to the laboratory himself to get the test results. Both the doctor’s visit and his nocturnal trip to the laboratory had in fact been a hallucination. An old lady who fought tooth and nail with the nursing staff explained later that she thought her bed was her grave. She made desperate attempts to climb out, but the nurses kept pushing her back in.

  More is gradually emerging about why some people are more prone to delirium than others. Delirium is basically caused by an overdose of the chemical messenger dopamine. There are a great many tiny variations, polymorphisms, in the DNA of the gene that produces the protein that receives the dopamine message in the brain cells. Those tiny variations are what make you more or less susceptible to delirium. Delirium causes brain damage and increases the risk of dementia. And its effects can last a long time. Many people experience long-term problems with reading, writing, walking, and memory and never recover entirely. Around a third of people over sixty-five who experience delirium die within a few months. So it’s a serious disorder and one whose risk is determined from the moment of conception.

  Hearing Voices

  It often takes quite a while for children to discover that other people don’t hear voices, after which they tend to be afraid to talk about such experiences.

  There are people who aren’t psychotic and yet do hear voices. In fact, between 7 a
nd 15 percent of the population hear voices, yet only a fraction have mental health problems. This phenomenon forms part of a spectrum, with healthy people who hear voices at one end and schizophrenia patients at the other. People who hear voices at the onset or in the wake of a psychosis are somewhere in the middle. In healthy individuals, hearing voices frequently starts at a young age and tends to run in families. It often takes quite a while for children to discover that other people don’t hear voices, after which they tend to be afraid to talk about such experiences. Some are very attached to their friendly voices, like the lady whose voices had told her since the age of eleven that there was no reason to be afraid. Patients with mental health problems, however, often hear voices with threatening, negative messages (“Why don’t you jump in front of a train today?” or “You must die, Evelyn, you’re evil, and evil people must die”). No wonder that voices like that produce paranoia and psychosis. By contrast, the voices that healthy people hear typically provide friendly help and advice, though there are cases of them saying nasty things like, “You’re ugly, you’re worthless, you’re fat.”

  Unlike psychotic patients, healthy people can control their voices. They can call them up as well as order them to go away at inconvenient times. Functional brain scans show that in the healthy group, brain activity isn’t very different from that of patients with psychosis. In both cases, activity is seen in Broca’s area (language production) and Wernicke’s area (hearing, processing, and understanding language) (fig. 8) and the primary auditory cortex is activated (fig. 22). It looks as if the links between those areas are disrupted, which would tie in with the theory that when input to a particular brain area is reduced, that area starts to produce its own information (see earlier in this chapter). In people who hear nasty voices, the right side of the brain is much more active. Attempts have been made to silence the voices by means of transcranial magnetic stimulation of the overactive area, but up to now that method has proved no more effective than placebos. I wonder how many people who work as TV psychics or claim to have paranormal gifts aren’t receiving messages from the other side but are just hearing their own brains.

  Olfactory Hallucinations

  Gershwin died at the age of thirty-eight, shortly after partial removal of a tumor of the uncus.

  The uncus (fig. 21) is a structure located in the front of the temporal lobe above the amygdala that is involved in smell. While conducting an orchestra, the famous composer George Gershwin suddenly started to smell burnt rubber and blacked out for ten to twenty seconds. He’d had an uncinate fit, which is an olfactory hallucination sometimes associated with epilepsy. Despite consulting a great many doctors, it took six months before Gershwin’s fits—which grew increasingly frequent—were shown to be caused by a tumor of the uncus. Gershwin died in 1937 at the age of thirty-eight, shortly after the tumor was partially removed.

  11

  Repair and Electric Stimulation

  I believe that the great diseases of the brain … will be shown to be connected with specific chemical changes in neuroplasm.… It is probable that by the aid of chemistry, many derangements of the brain and mind, which are at present obscure, will become accurately definable and amenable to precise treatment, and what is now an object of anxious empiricism will become one for the proud exercise of exact science.

  J.L.W. Thudichum, 1884

  AGE-RELATED BLINDNESS: MACULAR DEGENERATION

  Oh, the endless labor of the intellectual—pouring all this knowledge into the brain through a three-millimeter aperture in the iris.

  Irvin D. Yalom, When Nietzsche Wept, 1992

  My father went blind in the last year of his life. He lived to be eighty-nine. Fifteen years ago we would go to Leiden together every week, where he was undergoing laser treatment for degeneration of his retina. The retina, which evolves during fetal development from a bulge in the brain, converts light into electrical signals that the optic nerve transports to the back of the brain, where we see. When I arrived at the teaching hospital in Leiden for the first time with my practically blind father on my arm, I said, “We have to make a right here.” “How do you know that, have you been here before?” he asked. “No, but there’s a great big sign with an eye on it and an arrow pointing to the right,” I explained. Without missing a beat, he said, “I’d love to know what their signs for gynecology and obstetrics look like.” He had the most common form of age-related blindness: macular degeneration. It’s caused by new blood vessels growing right under the yellow spot (the macula), the part of the retina where you see the best. This destroys the retina, and you begin to lose your sight, starting in the middle of your field of vision. At first the objects you see are distorted, then a black spot forms in the middle of your central vision, which gradually becomes larger. In the wet form of macular degeneration, the new blood vessels leak blood and fluid. Reading and writing soon become impossible, and in the long run you can’t even make out large objects. On the journey back to Amsterdam after my father’s first laser treatment in Leiden, he asked me what month it was. “January,” I answered. “That’s odd,” said my father, “surely it’s much too early for the bulb season?” It turned out that the injection of fluorescent substance he had been given in preparation for the laser treatment made everything look yellow, creating the illusion that the tulip fields were in bloom. The laser therapy, alas, didn’t help preserve what little remaining sight he had.

  After my father’s death, laser treatment improved, and an effective therapy has recently been devised for wet macular degeneration. Antibodies like Avastin have now been developed that inhibit the vascular endothelial growth factor (VEGF), the molecule that prompts the growth of new blood vessels that destroy the retina. In order to halt the degenerative process, this substance has to be injected into the eye every month using an extremely thin needle. A similar substance called Lucentis has since been devised specifically for optical use. It is said to stabilize the condition in over 90 percent of patients and even improve vision in a third of this group. Other forms of therapy for macular degeneration are under development as well. In a short space of time, wet macular degeneration has gone from being an incurable to a treatable eye disease. The breakthrough in treating it came from Avastin, which was originally developed as a medication for intestinal cancer. That’s often the way in medicine: However carefully you target your approach to a particular disease, the breakthrough often comes from a completely unexpected sector.

  SERENDIPITY: A LUCKY ACCIDENT

  It’s not uncommon for medical findings to be made by accident, but you must keep an open mind and be able to make important deductions from apparently insignificant facts.

  If medication for Parkinson’s disease stops being effective, electrodes are sometimes implanted in a patient’s brain. They are then stimulated electrically by a pacemaker, which temporarily switches off activity in a small part of the brain. It’s very impressive to see how violent tremors suddenly stop when the patient switches on the stimulator. Yet this treatment is the result of serendipity, a lucky chance. In fact, it’s not uncommon for advances in medicine to be made by accident, when a doctor or researcher is exploring an entirely different avenue. In 1952, a Parkinson’s patient was set to undergo a drastic brain operation in a desperate attempt to stop his exceptionally severe tremors. The plan was to sever motoric pathways so as to paralyze the patient. During the operation, the surgeon, Irving Cooper, accidentally tore open a blood vessel. To stop the bleeding, the blood vessel was tied up, and the operation was abandoned. To everyone’s surprise, the patient’s tremors vanished. Cooper later went on to cauterize that blood vessel deliberately in other Parkinson’s patients, thus disconnecting a small region of the brain. He succeeded in reducing tremor in 65 percent of Parkinson’s patients and muscle rigidity in 75 percent. Subsequent experimental disconnection of different brain regions proved most successful in the area below the thalamus, the subthalamic nucleus (fig. 23). This is where most electrodes are still inserted in the brain
s of Parkinson’s patients. The nice thing about electrodes is that disconnection is reversible; as a result, you can see where they are most effective and can keep adjusting the way in which they are stimulated. This treatment alleviates symptoms like slowness of movement, muscle stiffness, and tremors, though it can’t slow the progress of the disease.

  Around thirty-five thousand people worldwide are going through life with depth electrodes in their brains. As in the case of any effective therapy, side effects have emerged. Some Parkinson’s patients with depth electrodes have problems interacting with their partners and co-workers. Although most patients were personally very satisfied with the quality of their lives, their relatives sometimes reported that they were more irritable and prone to mood swings. Around 9 percent experienced psychiatric side effects like increased impulsiveness or crying fits. Electrode stimulation can exacerbate depression. We have even seen cases where the patient committed suicide, despite the electrodes having been implanted at the right location in the subthalamic nucleus. (Ten years ago, neurologists wouldn’t have been interested in this correlation, but the boundary between neurology and psychiatry is fast becoming blurred.) Sometimes an implant can cause dementia symptoms because of bleeding or brain damage. But these symptoms occasionally disappear if the stimulator is configured differently. Cases have also been reported of psychosis, sexual disinhibition, and gambling addiction. One patient who had been a typical tightfisted Dutchman prior to the operation couldn’t resist the lure of slot machines afterward. It was only years later, when his mounting debts forced him to sell his house, his wife demanded a divorce, and he tried to commit suicide, that the problem was brought to the attention of his doctors. (Gambling addiction can also be a side effect of the classic medication for Parkinson’s, L-dopa, the dopamine system [fig. 16] being central to addiction.) Another patient treated with electrodes became manic and started buying houses in Spain and Turkey, something he really couldn’t afford to do. But he absolutely refused to have the stimulator switched off.