The Future of the Mind (28 page)

The future belongs to those who believe in the beauty of their dreams.

—ELEANOR ROOSEVELT

7
IN YOUR DREAMS

Dreams can determine destiny.

Perhaps the most famous dream in antiquity took place in the year A.D. 312, when the Roman emperor Constantine engaged in one of the greatest battles of his life. Faced with a rival army twice the size of his own, he realized that he probably would die in battle the next day. But in a dream he had that night, an angel appeared before him bearing the image of a cross, uttering the fateful words “By this symbol, you shall conquer.” Immediately he ordered the shields of his troops adorned with the symbol of the cross.

History records that he emerged triumphant the next day, cementing his hold on the Roman Empire. He vowed to repay the blood debt to this relatively obscure religion, Christianity, that had been persecuted for centuries by previous Roman emperors and whose adherents were regularly fed to the lions in the Colosseum. He signed laws that would eventually pave the way for it to become an official religion of one of the greatest empires in the world.

For thousands of years, kings and queens, as well as beggars and thieves, have all wondered about dreams. The ancients considered dreams to be
omens about the future, so there have been countless attempts throughout history to interpret them. The Bible records in Genesis 41 the rise of Joseph, who was able to correctly interpret the dreams of the Pharaoh of Egypt thousands of years ago. When the Pharaoh dreamed about seven fat cows, followed by seven lean cows, he was so disturbed by the imagery that he asked scribes and mystics throughout the kingdom to find its meaning. All failed to give a convincing explanation, until Joseph finally interpreted the dream to mean that Egypt would have seven years of good harvests, followed by seven years of drought and famine. So, said Joseph, Egypt must begin stockpiling grain and supplies now, in preparation for the coming years of want and desperation. When this came to pass, Joseph was considered to be a prophet.

Dreams have long been associated with prophesy, but in more recent times they’ve also been known to stimulate scientific discovery. The idea that neurotransmitters could facilitate the movement of information past a synapse, which forms the foundation of neuroscience, came to pharmacologist Otto Loewi in a dream. Similarly, in 1865, August Kekulé had a dream about benzene, in which the bonds of carbon atoms formed a chain that eventually wrapped around and finally formed a circle, just like a snake biting its tail. This dream would unlock the atomic structure of the benzene molecule. He concluded, “Let us learn to dream!”

Dreams have also been interpreted as a window onto our true thoughts and intentions. The great Renaissance writer and essayist Michel de Montaigne once wrote, “I believe it to be true that dreams are the true interpretations of our inclinations, but there is art required to sort and understand them.” More recently, Sigmund Freud proposed a theory to explain the origin of dreams. In his signature work,
The Interpretation of Dreams
, he claimed that they were manifestations of our subconscious desires, which were often repressed by the waking mind but which run wild every night. Dreams were not just the random figments of our overheated imaginations but could actually uncover deep secrets and truths about ourselves. “Dreams are the royal road to the unconscious,” he wrote. Since then, people have amassed huge encyclopedias that claim to reveal the hidden meaning behind every disturbing image in terms of Freudian theory.

Hollywood takes advantage of our continuing fascination with dreams. A favorite scene in many movies is when the hero experiences a terrifying dream sequence and then suddenly wakes up from the nightmare in a cold sweat. In the blockbuster movie
Inception
, Leonardo DiCaprio plays a petty
thief who steals intimate secrets from the most unlikely of all places, people’s dreams. With a new invention, he is able to enter people’s dreams and deceive them into giving up their financial secrets. Corporations spend millions of dollars protecting industrial secrets and patents. Billionaires jealously guard their wealth using elaborate codes. His job is to steal them. The plot quickly escalates as the characters enter dreams in which a person falls asleep and dreams again. So these criminals descend deeper and deeper into multiple layers of the subconscious.

But although dreams have always haunted and mystified us, only in the last decade or so have scientists been able to peel away the mysteries of dreams. In fact, scientists can now do something once considered impossible: they are able to take rough photographs and videotapes of dreams with MRI machines. One day, you may be able to view a video of the dream you had the previous night and gain insight into your own subconscious mind. With proper training, you might be able to consciously control the nature of your dreams. And perhaps, like DiCaprio’s character, with advanced technology you might even be able to enter someone else’s dream.

THE NATURE OF DREAMS

As mysterious as they are, dreams are not a superfluous luxury, the useless ruminations of the idle brain. Dreams, in fact, are essential for survival. Using brain scans, it is possible to show that certain animals exhibit dreamlike brain activity. If deprived of dreams, these animals would often die faster than they would by starvation, because such deprivation severely disrupts their metabolism. Unfortunately, science does not know exactly why this is the case.

Dreaming is an essential feature of our sleep cycle as well. We spend roughly two hours a night dreaming when we sleep, with each dream lasting five to twenty minutes. In fact, we spend about six years dreaming during an average lifetime.

Dreams are also universal across the human race. Looking across different cultures, scientists find common themes in dreams. Fifty thousand dreams were recorded over a forty-year time period by psychology professor Calvin Hall.
He followed this up with one thousand dream reports from college students. Not surprisingly, he found that most people dreamed of the same things, such as personal experiences from the previous days or week.
(However, animals apparently dream differently than we do. In the dolphin, for example, only one hemisphere at a time sleeps in order to prevent drowning, because they are air-breathing mammals, not fish. So if they dream, it is probably in only one hemisphere at a time.)

The brain, as we have seen, is not a digital computer, but rather a neural network of some sort that constantly rewires itself after learning new tasks. Scientists who work with neural networks noticed something interesting, though. Often these systems would become saturated after learning too much, and instead of processing more information they would enter a “dream” state, whereby random memories would sometimes drift and join together as the neural networks tried to digest all the new material. Dreams, then, might reflect “house cleaning,” in which the brain tries to organize its memories in a more coherent way. (If this is true, then possibly all neural networks, including all organisms that can learn, might enter a dream state in order to sort out their memories. So dreams probably serve a purpose. Some scientists have speculated that this might imply that robots that learn from experience might also eventually dream as well.)

Neurological studies seem to back up this conclusion. Studies have shown that retaining memories can be improved by getting sufficient sleep between the time of activity and a test. Neuroimaging shows that the areas of the brain that are activated during sleep are the same as those involved in learning a new task. Dreaming is perhaps useful in consolidating this new information.

Also, some dreams can incorporate events that happened a few hours earlier, just before sleep. But dreams mostly incorporate memories that are a few days old. For example, experiments have shown that if you put rose-colored glasses on a person, it takes a few days before the dreams become rose-colored as well.

BRAIN SCANS OF DREAMS

Brain scans are now unveiling some of the mystery of dreams. Normally EEG scans show that the brain is emitting steady electromagnetic waves while we are awake. However, as we gradually fall asleep, our EEG signals begin to change frequency. When we finally dream, waves of electrical energy emanate from the brain stem that surge upward, rising into the cortical areas of
the brain, especially the visual cortex. This confirms that visual images are an important component of dreams. Finally, we enter a dream state, and our brain waves are typified by rapid eye movements (REM). (Since some mammals also enter REM sleep, we can infer that they might dream as well.)

While the visual areas of the brain are active, other areas involved with smell, taste, and touch are largely shut down. Almost all the images and sensations processed by the body are self-generated, originating from the electromagnetic vibrations from our brain stem, not from external stimuli. The body is largely isolated from the outside world. Also, when we dream, we are more or less paralyzed. (Perhaps this paralysis is to prevent us from physically acting out our dreams, which could be disastrous. About 6 percent of people suffer from “sleep paralysis” disorder, in which they wake up from a dream still paralyzed. Often these individuals wake up frightened and believing that there are creatures pinning down their chest, arms, and legs. There are paintings from the Victorian era of women waking up with a terrifying goblin sitting on their chest glaring down at them. Some psychologists believe that sleep paralysis could explain the origin of the alien abduction syndrome.)

The hippocampus is active when we dream, suggesting that dreams draw upon our storehouse of memories. The amygdala and anterior cingulate are also active, meaning that dreams can be highly emotional, often involving fear.

But more revealing are the areas of the brain that are shut down, including the dorsolateral prefrontal cortex (which is the command center of the brain), the orbitofrontal cortex (which can act like a censor or fact-checker), and the temporoparietal region (which processes sensory motor signals and spatial awareness).

When the dorsolateral prefrontal cortex is shut down, we can’t count on the rational, planning center of the brain. Instead, we drift aimlessly in our dreams, with the visual center giving us images without rational control. The orbitofrontal cortex, or the fact-checker, is also inactive. Hence dreams are allowed to blissfully evolve without any constraints from the laws of physics or common sense. And the temporoparietal lobe, which helps coordinate our sense of where we are located using signals from our eyes and inner ear, is also shut down, which may explain our out-of-body experiences while we dream.

As we have emphasized, human consciousness mainly represents the brain constantly creating models of the outside world and simulating them into the future. If so, then dreams represent an alternate way in which the future is simulated, one in which the laws of nature and social interactions are temporarily suspended.

HOW DO WE DREAM?

But that leaves open this question: What generates our dreams? One of the world’s authorities on dreams is Dr. Allan Hobson, a psychiatrist at Harvard Medical School. He has devoted decades of his life to unveiling the secrets of dreams. He claims that dreams, especially REM sleep, can be studied at the neurological level, and that dreams arise when the brain tries to make sense of the largely random signals emanating from the brain stem.

When I interviewed him, he told me that after many decades of cataloging dreams, he found five basic characteristics:

1. Intense emotions—this is due to the activation of the amygdala, causing emotions such as fear.

2. Illogical content—dreams can rapidly shift from one scene to another, in defiance of logic.

3. Apparent sensory impressions—dreams give us false sensations that are internally generated.

4. Uncritical acceptance of dream events—we uncritically accept the illogical nature of the dream.

5. Difficulty in being remembered—dreams are soon forgotten, within minutes of waking up.

Dr. Hobson (with Dr. Robert McCarley) made history by proposing the first serious challenge to Freud’s theory of dreams, called the “activation synthesis theory.” In 1977, they proposed the idea that dreams originate from random neural firings in the brain stem, which travel up to the cortex, which then tries to make sense of these random signals.

The key to dreams lies in nodes found in the brain stem, the oldest part of the brain, which squirts out special chemicals, called adrenergics, that keep us alert. As we go to sleep, the brain stem activates another system, the cholinergic, which emits chemicals that put us in a dream state.

As we dream, cholinergic neurons in the brain stem begin to fire, setting off erratic pulses of electrical energy called PGO (pontine-geniculate-occipital) waves. These waves travel up the brain stem into the visual cortex, stimulating it to create dreams. Cells in the visual cortex begin to resonate hundreds of times per second in an irregular fashion, which is perhaps responsible for the sometimes incoherent nature of dreams.