A. Ever since Sigmund Freud published his controversial theories about the meaningof dreams in 1900, we have been fascinated with the experiences we seem to livethrough while we sleep. Freud was convinced that dreams represent some unfulfilleddesires or hoped-for wishes, while later investigators saw a more pragmatic qualityto them, as reflection of waking life. None of these theories, however, have had thebenefit of much in the way of solid, objective data.
B. At least, until now. Two new developments in research--brain imaging and bigdata--may offer some stronger answers. More detailed and timely photos of the brainat work, combined with the information researchers collected about dreams fromexperiments in sleep labs, are gradually peeling away the mystery of dreams, andrevealing their meaning.
C. From a strictly biological standpoint, scientists have learned much about thephysiological process of dreaming, which occurs primarily in REM (Rapid EyeMovement) sleep. "During dreaming," says Patrick McNamara, a neurologist ( 神经病学家 ) at Boston University School of Medicine and the graduate schoolof Northcentral University in Prescott Valley, Ariz., "the emotional part gets highlyactivated while the executive part of the brain is under-activated. So the kind ofcognitions we experience during dreams are highly emotional, visually vivid, butoften illogical, disconnected and sometimes bizarre." That suggests that our dreamsmay have some role in emotional stability.
D. That does not necessarily mean, most dream researchers believe, that dreams arerandom expressions of emotion or lack of intellectual meaning. While some scientistsmaintain that dream patterns are strictly the result of how different neurons ( 神经元 )in the brain are firing, Deirdre Barrett, a psychologist and dream researcher at HarvardMedical School, believes they represent something more. "I think dreams are thinkingin a different biochemical state."
E. Defining that state, not to mention understanding the rules under which that universeoperates, however, is a challenge. It may represent a complex interaction betweenemotional and cognitive information, says McNamara, so that dreams serve tohelp our brains process emotional memories and integrate them into our long-termmemories. And because traumatic ( 创伤的) events are associated with higher levelsof the stress hormone cortisol (皮质醇 ) , they can cause nightmares. Researchersbelieve that excessive amounts of cortisol can impair the two main brain systems thatintegrate memory. "The memories don't get integrated," he says, "but just sit around.In post traumatic stress disorder, they get re-experienced over and over."
F. In fact, from sleep studies in which people were exposed to images, leaming tasks orother experiences immediately before they dozed off and then examined when theyawakened, many scientists believe that dreams can help us rehearse for challengesor threats we anticipate--emotionally, cognitively and even physiologically. Inour dreams we may try out different scenarios to deal with what's coming up.Although much of the evidence lack of scientific support, McNamara says, someonepracticing piano or playing video games in waking life may start to do the same whiledreaming. People solving a puzzle or studying a foreign language, he adds, can havebreakthroughs with dreams that go beyond the perceptions that simply taking a breakfrom the problem can produce.
G. And now, Barrett says, brain imaging holds the promise of being able to helpscientists "see" what until now could only be reported by subjective, possiblyinaccurately recalled, dream accounts. For example, in research with rats trained torun through mazes to get rewards, investigators were able to record neuron activityin sleeping rats and determined that the rats were running the same mazes in theirdreams.
H. In other experiments with humans, scientists monitored volunteers who slept insidean FMRI ( 功能性磁共振成像 ) scanner while hooked up to EEG ( 脑电图描记器 )electrodes that measured brain wave activity. When the EEG indicated they weredreaming, the participants were awakened and asked what images they had seenin their dreams. The investigators were later able to match certain patterns of brainactivity to certain images for each person. "There's a crude correspondence betweenthe brain scan and the image. From the scan, you can guess it's an animal with fourlegs," says Barrett. Despite the primitive state of this dream decoding (解码 ) , theability to actually get content from a dream is getting closer.
I. Mining big data bases of reported dreams holds another kind of promise. Untilnow, researchers have been working on relatively small samples of dream accounts,usually fewer than 200 per study. But new dream websites and smartphone apps likeDreamBoard and Dreamscloud are encouraging thousands of people to report theirdreams so researchers can finally answer their most urgent questions. McNamara, for example, is excited to study dreams from different countries to see whether there are cultural differences in what people's brains do when they aren't awake.
J. The data bases also provide an opportunity to investigate the intriguing but under- studied realm of sex dreams. Until recently, says McNamara, they represented only 10% of reported dreams, likely because people are not eager to share this type of content with researchers in white lab coats. But self-reporting via the apps andwebsites, despite its potential biases, may provide more information on these types of dreams. "This is a wide open area crying for investigation," he says.
K. McNamara is also eager to study individuals' dreams over time to observe differencesand changes in emotional tone, colors, words and other significant patterns andconnect these to events in their lives. That would bring him closer to answeringwhether dreams can, in fact, predict things--it might be possible, for example,that certain kinds of dreams precede getting the flu, or that other dreams are moreassociated with happier events.
L. Such investigations could also reveal more about less welcome dreams, such asnightmares, and potentially lead to ways to control or avoid them. Barrett plans tomine the new database to study how often nightmares occur, and how they relate toan individual's trauma or a family history of anxiety disorder. One of her first projectswill involve the dream data from DreamBoard.com, which has accumulated 165,000dreams over the last two years. Because Drearrd3oard has coded the dreams by thegender, colors, emotions (joy, anxiety, anger) and the number and categories of peoplein a dream, Barrett says she can identify basic patterns.
M. We already know, she says, that women dream equally about men and women whilemen's dreams are two-thirds populated by men. Research so far also shows that men'sdreams may show slightly more anger and physical aggression while women's displaya bit more sadness and verbal hostility. Interpreting what these differences mean,however, will require deeper studies.
N. What's been discovered so far, however, suggests that such studies could reveal anenormous amount about what role dreams play in our lives, and how important theyare for biological, psychological or social reasons. With this research, McNamarabelieves, scientists can find out if what shrinks (精神病学家) have been sayingfor years is true--that reflecting on our dreams is useful and can give us insight intoourselves. Psychologists say so, and many people think so. But this research, he says,gives us the potential to know.