We Are Our Brains (45 page)

Gert van Dijk, a Dutch neurologist at Leiden University Medical Center, carries out weekly trials that involve making patients faint. They regularly experience NDEs in which they hear voices, have pleasant sensations, or feel that they're in another world entirely. All of these symptoms are caused by well-documented temporary impairment to blood circulation in the brain; Van Dijk measures the point at which the EEG flatlines (though the brain stem continues to function, because the patients are still breathing). Yet Van Lommel repeatedly maintains in his book that NDEs can't be caused by lack of oxygen to the brain, because then everyone who had a heart attack would experience them. He forgets that longer periods of oxygen deprivation impair memory so much that you can't remember an NDE, even though he mentions this himself in a study published in
The Lancet.
Van Lommel's study also shows that some people are more prone than others to experience or recall NDEs. This has to do with the extent to which dream sleep (REM sleep) can surface during consciousness, as the American neurologist Kevin Nelson has shown. When REM sleep intrudes during an NDE, people's muscles relax as they normally do in dreams, preventing them from moving or speaking, just as in narcolepsy (see
chapter 5
). This REM paralysis contributes to the feeling of being dead. Van Lommel also rejects the notion that NDEs are caused by oxygen shortage on the grounds that severe stress has also been shown to induce NDEs. However, that can easily be attributed to the brain's response to cortisol and other stress signals. When pain or stress becomes unbearable, when escape from a life-threatening situation is impossible, the brain resigns itself and REM sleep intrudes. The stress system is switched off and the dream
stage of the NDE begins, along with pleasant sensations. How can Van Lommel actually be so sure that all brain activity stops during unconsciousness? Gert van Dijk disproves this on a regular basis. (His flatlining EEGs don't show that all activity has ceased—an EEG only measures activity in the upper part of the cerebral cortex.) Moreover, when someone has a heart attack, the interval between normal brain function and the onset of unconsciousness is long enough for them to have an NDE. The same applies to the interval between unconsciousness and recovery, which is when Dostoyevsky would have his seemingly endless experiences during epileptic seizures. The possibility of NDEs occurring when consciousness returns is underpinned by the fact that some people feel themselves flopping back into their bodies at the moment of successful reanimation.

There are no scientific grounds for Van Lommel's peculiar theory, whereas brain research perfectly explains all aspects of NDEs. An out-of-body experience can be triggered by stimulating the place where the temporal lobe and the parietal lobe meet. If the processing of information from the muscles, the organ of balance, and the visual system is disrupted at the spot where the temporal lobe and the parietal lobe meet—the angular gyrus (
fig. 28
)—you get the sensation of leaving your body and floating around. Similar experiences have been generated by cannabis use, which influences a great many chemical messengers in the brain. In one patient's case, electrical stimulation at the rear of the hypothalamus near the fornix (
fig. 26
) had the side effect of activating the medial temporal lobe, causing him to reexperience events that had taken place thirty years earlier (see
chapter 11
) and creating the NDE-like effect of his life flashing past. This area is involved in storing the episodic autobiographical memories that form the chronicle of our lives. It is, moreover, extremely sensitive to lack of oxygen and therefore can be easily activated. Stimulating the hippocampus provokes extremely clear, highly detailed autobiographical memories, including memories of people who have died. When one's life is in acute danger it appears that all of these memories are retrieved not one after the other but virtually
simultaneously, leading to what is called “panoramic memory.” As we know from temporal lobe epilepsy and other situations in which the temporal lobe is stimulated (see
chapter 15
), this can go hand in hand with strong spiritual or religious feelings. People feel that they are one with the universe, the world, or God, or they think that they have gone to heaven or the afterlife and are in direct contact with God, Jesus, or some other religious figure. The feeling of tranquility and the absence of pain in NDEs is ascribed to the release of opiates or stimulation of the brain's reward system. The vision of a tunnel is caused by reduced blood circulation in the eyeball, starting on the periphery of the field of vision. The periphery grows dark while the center of the visual field remains clear, creating the impression of a tunnel with light at the far end. Fighter pilots trained in a giant centrifuge that impaired blood circulation in their eyes also saw such tunnels. The bright, attractive colors and the beautiful light at the end of the tunnel are caused by stimulation of the visual cortex, just as when we dream. And just as in a dream, a person experiencing an NDE finds themselves taking part in a bizarre story.

FIGURE 28.
An out-of-body experience can be induced by stimulating the place where the temporal lobe (which is very susceptible to oxygen deficiency) and the parietal lobe meet: the angular gyrus. If the processing of information from the muscles, the organ of balance, and the visual system is disrupted at this location, you get the sensation of leaving your body and floating about.

Van Lommel's theory boils down to our brains and our DNA being receivers for “waves of consciousness,” a term that he doesn't go on to define. In his explanations he frequently uses terms like
entanglement, nonlocality
, and other terms borrowed from quantum mechanics. The theoretical physicist Robbert Dijkgraaf, president of the Royal Netherlands Academy of Arts and Sciences, better qualified than I to pronounce on questions of physics, is clear in his opinion. “When faced with the inexplicable, people like to believe that quantum mechanics must provide the answer. But unfortunately all the characteristics of quantum systems vanish with incredible speed if you put more than a few particles together. Entanglement and nonlocality (involving particles being connected with each other and able to influence each other at a distance) occur only under exceptional circumstances: at a temperature of one billionth of a degree above absolute zero and in extremely well-isolated surroundings. The quantum world is incompatible with a warm, complex system like the human brain or the world around it. That can be demonstrated in five minutes on the back of an envelope.”

Irresponsible Scaremongering

Van Lommel is of course free to put forward spiritual theories that aren't supported by any research. There's nothing new about his ideas. They have been around for thousands of years, held by many cultures, mystical movements, and religions. However, he should not fool people by giving his book the subtitle
The Science of the Near-Death Experience.
Nor should he, a doctor, frighten off potential organ donors with his completely unscientific theories. It's baffling that he presents the nonsensical tales of organ recipients acquiring donor characteristics (see earlier in this chapter) as if they were truths. While claiming not to be against organ transplantation, he is wilfully scaring potential donors and their families unnecessarily.

Various hospitals are currently attempting to collect evidence of out-of-body experiences during an NDE. Researchers have placed
playing cards on top of cabinets in the rooms of patients in order to test whether people see the cards when they are ostensibly floating above their bodies. As you might expect, patients who felt they were leaving their bodies haven't been able to identify the cards. So all in all, there's no reason whatsoever to regard NDEs as proof of observations outside the brain, or as evidence of life after death. Those patients never got as far as the hereafter.

In short, near-death isn't the same as death, just as near-pregnant isn't the same as pregnant.

The discovery that the most commonly used antidepressants aren't significantly more clinically effective than a placebo was met with general amazement. It seems that physicians are strangely reluctant to sing the praises of the placebo effect, which occurs when patients show improvement after being given an essentially ineffective compound or treatment. As a rule, ineffective pills that are red, yellow, or orange are perceived to have a stimulating effect, while blue and green pills are deemed calming. Placebos can also have side effects, like nausea or stomachache. You can even get addicted to placebos, experiencing withdrawal symptoms when treatment stops. So the effectiveness and neurobiological mechanisms of placebos make a very interesting subject for investigation.

The placebo effect results from unconscious changes in brain function that reduce the symptoms of a disease. It is caused by the patient's own expectations of treatment. While the substances in placebos are pharmacologically ineffective, their effect can be quite considerable. The placebo effect isn't confined to pills; it also extends
to psychotherapy, surgical interventions, and other therapies. For many years, psychiatric patients were advised to breathe into a paper bag if they felt a panic attack coming on, an approach that proved very successful. It was based on the theory that when you hyperventilate, you exhale too much carbon dioxide, ultimately causing a panic attack. But it later turned out that hyperventilation wasn't the cause but the consequence of a panic attack and that breathing in extra carbon dioxide from a paper bag should theoretically induce a panic attack rather than relieve it. But because people believed in it, it worked.

Placebos can help to relieve the symptoms of Parkinson's disease (caused by a lack of the chemical messenger dopamine) by making the brain release more dopamine. A similar effect can also be obtained by using electrodes implanted in the brain to inhibit the subthalamic nucleus. If a doctor tells a patient that he's switching the electrode's simulator on or off but doesn't in fact do so, the patient's symptoms nevertheless improve or worsen accordingly. During an operation to implant depth electrodes, an ineffective substance was injected into the intravenous line of Parkinson's patients, who were told that it was a new anti-Parkinson's drug. Electrical activity in that same brain area diminished as a result, reducing symptoms in over half of the cases. It seems that the brains of the patients responding to the placebo “know” in which area a change in activity is needed to alleviate symptoms.

Depressive patients who were treated with a placebo showed the same improvements after six weeks as patients who'd been given real antidepressants. Brain scans showed that changes in activity patterns were very similar in both categories of patient. So the brain can be prompted by a placebo to bring about the exact functional changes that are needed to reduce the symptoms of depression: increased activity in the prefrontal cortex and reduced activity in the hypothalamus.

If a patient is in pain and is given a placebo, the brain “knows” how to suppress the pain by releasing more endorphins (morphine-like
substances) and cannabis-like compounds and altering activity patterns in certain areas of the brain and spinal cord. An expensive placebo proves more effective than a cheap placebo. By contrast, because of their dementia, Alzheimer's patients don't expect painkillers to help. As a result, they don't work as well, and such patients need to be given higher doses to achieve the same effect. The placebo effect is the result of the brain's own unconscious self-healing potential. That mechanism can contribute little or nothing to the treatment of cancer but has been proven effective in a number of brain disorders. Studies of the mechanism of placebo effects and of why some people are more receptive to them than others (including whether a predisposition to spirituality plays a role) could have important clinical consequences. In the meantime we certainly mustn't underestimate the effectiveness of the doctor figure, whose traditional power to inspire confidence makes him a walking placebo.

Since time immemorial, traditional Chinese medicine (TCM) has held that an incredible number of substances and foods are good for your health. In fact, the Chinese like to claim that everything that's tasty is good for you and will prolong life. But there are also serious studies suggesting that the widely publicized benefits of unfermented green tea are well founded: It appears to reduce the risk of cardiovascular diseases and certain forms of cancer. Based on seventeen national screening trials, it's estimated that you're 10 percent less likely to have a heart attack if you drink three large cups of green tea a day. Green tea is thought not only to counteract high blood pressure and obesity but also to protect the brain. Various traditional Chinese herbal preparations are believed to diminish dementia symptoms,
and modern techniques are being used to determine their active ingredients and functional mechanisms. Cat's claw herb (
Uncaria rhynchophylla
) combats beta-amyloid plaques and so might be effective against Alzheimer's. However, claims that green tea can combat Parkinson's and Alzheimer's still need further evidence. In TCM, millipedes, beetles, and worms are traditionally held to counteract dementia. Extracts from these creatures have indeed been shown to inhibit acetylcholine esterase activity, just as the Western medicine prescribed for Alzheimer's does, which does help certain patients to a degree. It's by no means impossible that Chinese research into traditional medicines will bring to light entirely new active substances.