How to build a dream – how the brain creates dreams – Hot News
Somehow you overslept, and by the time you get to class, there’s only 10 minutes left to finish the exam. More troublesome, though, is the fact that you’re completely naked, and when you glance toward the front of the room, it’s not your math teacher standing there but your mother, chomping contemptuously on a fat Cuban cigar.
It’s only a dream, of course. But it seemed so real, so vivid, so symbolic, that it must mean something. Freud, after all, argued that dreams are the “royal road to the unconscious,” our innermost thoughts unshackled from the confinement of our uptight, waking self. Figure out what your dreaming mind is trying to telling you, said Uncle Siggy, and you’ll achieve deeper self-understanding.
But modern cognitive neuroscience suggests that Freud had it wrong, that dreams have little or no inherent meaning. According to this new view, the images, objects, and characters in our dreams are not coded postcards from our psyche, but the product of semi-random neuronal firings. And the bizarre plots and storylines of dreams merely reflect a desperate attempt by our brain to somehow make sense of this chaos.
Night Visions
Dreams are such a routine part of our lives that we often don’t appreciate just how bizarre the very concept of dreaming is.
“The mind becomes clinically insane for two hours every night,” Robert Stickgold, Ph.D., a Harvard neuroscientist, told the American Psychological Association. “We hallucinate wildly, see and hear things that aren’t there. We become delusional.”
By tracing what happens in the brain during these hallucinations, and analyzing the content of dreams in objective ways, Stickgold and colleague J. Allan Hobson, M.D., director of Harvard’s Neurophysiology Lab, are helping create a bold new model of dreaming.
Dreaming, they contend, is a bottom-up process. It’s initiated by one of the brain’s most primitive regions, the pontine brainstem, or pons.
Although many parts of the brain contribute to dreaming, one of the key players on the Dream Team is a pons region called the FTG (the full name, if you must know, is gigantocellular field of the tegmentum). FTG neurons spring into action as the brain shifts into REM sleep, those nocturnal periods during which your eyes dart frantically from side to side and your dreams are longest and most numerous.
Over the course of a night, most of us pass through four to six cycles of REM, each lasting 15 to 30 minutes. Just before a REM cycle begins, the FTG sends bursts of electrical signals throughout the brain–and dream construction begins in earnest.
But before a dream has a plot, characters, or setting, it gets assigned an emotion, contends Stickgold. Some of those electrical signals reach one of the brain’s emotional centers, the amygdala, which “chooses” a mood or emotion from some mental menu.
Whether the proportion of each emotion that winds up in our dreams is somehow fixed in our brain, or whether the amygdala relies on some emotional “thermostat” sensitive to culture and environment, isn’t yet known.
If dreams are mirrors of our waking lives–or, alternatively, if they represent the emotions we keep pent-up during the day–we would expect to see sex differences in dream emotions.
That’s because during the day, men and women typically report different emotional states. Men are more likely than women to say they’re angry; women are more often anxious or depressed.
But Hobson and Stickgold find that the emotional content of dreams is identical in both males and females. Fear and anxiety dominate about a third of our dreams; another 15 percent involve anger. In all, about two-thirds of dreams are emotionally negative–and they typically become more unpleasant as the dream progresses. It might be due to a kind of cognitive-emotional feedback: Negative emotions remind the dreamer of negative thoughts, which leads to higher levels of emotional negativity.
A Terribly Awkward Position
Meanwhile, the electrical waves from the FTG also activate higher brain regions like the cerebral cortex. These are the brain cells that supply memories and visual images, the nuts and bolts of dreams.
But during REM sleep, low-level chaos occurs within the cortex, reports Steve Foote of the University of California, San Diego. Neurons that receive the signal to fire somehow remain silent, while others go off for no apparent reason.
Technically, this chaos is called a decrease in the signal-to-noise ratio. But the practical upshot is a mishmash of images, thoughts, and emotion that puts our association cortex in a terribly awkward position: It wants to tie everything together.
This may be why our dreams seem so bizarre, says Stickgold. “It is all that the association cortex can do to cobble together some fantastic story line and try to keep up this chaotic melange of images and feeling.”
Seen Any Object Transformations Lately?
The Harvard team has been attempting to document the bizarreness by analyzing the content of dreams in a scientifically objective fashion–a harder task than might first appear. Part of the problem is, we can’t rely on dreamers themselves to interpret their own dreams because they will find meaning at every turn.
“The human brain is an association maker,” observes Stickgold. “It will find associations between almost any two images presented side by side or sequentially. It finds meaning in Rorschach ink blots, in tarot cards, in the arrangements of stars.”
The trick, then, is to bring in objective observers. That’s what Cindi Rittenhouse, then at Harvard, did when she studied that most bizarre dream phenomenon, the metamorphosis of one person or object into another-so-called object transformations. She arranged, side-by-side, lists of dream objects and the things they turned into, then asked judges to match one side of the list with the other. Did the bag in one person’s dream, for example, turn into a school bus, a beach, or a burlap sack?
The answer, not surprisingly, is the burlap sack. In fact, most of the transformations proved so predictable that a panel made correct matches 94 percent of the time. Transformations, in other words, aren’t random, but reflect object associations that most of us would make. But the same doesn’t hold true of the location or plot changes that sometimes occur in mid-dream–“as if you were watching TV and someone changed the channel,” notes Stickgold. In one study, elaborate symbolic interpretations on a dream–that a rose, for instance, represents nostalgia for your lost youth, or that anything cylindrical has phallic implications.
“This sort of stuff is dearly nonsensical,” Stickgold says. His take-home message: Find all the meaning you want in your dreams–but understand that such meaning is constructed by our waking minds after the dream, not by some dreaming unconscious beforehand.
Perhaps it was frustration with such overwrought Freudian interpretation that led novelist Stephen King to offer his own theory on dreaming. Its philosophy isn’t all that far removed from what Stickgold and Hobson propose. And whatever it lacks in delicacy, it more than makes up for in insight. “I think that a lot of times,” King said, “dreams are nothing more than a kind of mental or spiritual flatulence.”
COPYRIGHT 1995 Sussex Publishers, Inc.
COPYRIGHT 2004 Gale Group