It’s happened to all of us---something wakes you smack in the middle of a random, Technicolor assortment of people, rooms, buildings and streets. They were all interacting as if it made sense, and then you can remember hardly anything from the dream. But what if you didn't have to? What if a machine could read your dreams? A team of researchers in Japan has established that the contents of dreams can be discerned by monitoring the brain's visual centers while people are asleep. The finding opens the door to a dream decoder that could tell us what we dream about, even if we forget it upon awaking. The study observed three participants as they laid in a functional MRI (fMRI) scanner. The participants were allowed to doze off and were awoken just as they started to fall asleep (i.e., before REM sleep). Upon waking they were asked to describe what they were seeing in their dreams---maybe a car moving down a street, a person drinking coffee in a sunny café, or a cat in the neighbor’s yard. Participants were woken at least 200 times, or about every 5.7 minutes, just as they were slipping into sleep, and researchers logged each dream description. Each participant's descriptive words filled a personalized database. Specific words were categorized more generally, into about 20 categories per person: For example, ice pick, key and plunger were all grouped under the category "implement." Researchers then found images online that matched these general categories and showed them to participants while awake. MRI recordings matched up with categories to train the computer to pick out the neural "signature" of each category of things. The result was a personalized dream-detector for each participant. When the researchers tested the software in a second round of sleep tests, they were able to predict the category of a person's immediately preceding dream visualizations with 60% accuracy, they report
today in the journal Science. Thus, in principle, the team established that visual information results in similar brain patterns whether a person is awake and looking at an image on the Web or is dreaming just before falling asleep. The work may lead to a dream detector that could re-create dream content that's forgotten upon awaking. However since the classic dreaming stage of sleep is REM sleep, further studies will need to be done to see if REM dreams are also detectable in this way. Image courtesy dragon_fang / Shutterstock
