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Here's how the study worked. Subjects were first asked to hook themselves up to an electroencephalography (EEG) machine, then to fall asleep within an fMRI machine. Scientists used the EEG readings to identify when the subjects began to enter a dreaming phase.
Rapid eye movement, or REM, sleep is a fascinating period when most of our dreams are made. Now, in a study of mice, a team of Japanese and U.S. researchers shows that it may also be a time when the brain actively forgets. They also uncovered clues suggesting that these cells may play a role in learning and memory.
The remarkable breakthrough makes use of a fairly straightforward idea: that when we visualize certain types of objects in our minds, our brains generate consistent neural patterns that can then be correlated with what is being visualized. The research could eventually revolutionize how dreams are interpreted and understood. Scientists may even glean valuable clues about what the mysterious function of dreaming is in the first place.
For instance, when you imagine a chair, your brain fires in a pattern that occurs whenever a chair is visualized. An algorithm can then be used to tie the data from a brain scan to the appropriate correlated images. And voilà! Your dream can be reconstructed.
To test this idea, the researchers used a variety of genetic tools to turn on and off MCH neurons in mice during memory tests. Specifically, they examined the role that MCH cells played in retention, the period after learning something new but before the new knowledge is stored, or consolidated, into long-term memory. The scientists used several memory tests including one that assessed the ability of mice to distinguish between new and familiar objects.
In agreement with previous studies, the researchers found that a majority (52.8%) of hypothalamic MCH cells fired when mice underwent REM sleep whereas about 35% fired only when the mice were awake and about 12% fired at both times.
Why it’s so promising?
“Understanding the role of sleep in forgetting may help researchers better understand a wide range of memory-related diseases like post-traumatic stress disorder and Alzheimer’s Their labs and others have helped to show how narcolepsy may be linked to the loss of hypocretin/orexin-making neurons in the hypothalamus, a peanut-sized area found deep inside the brain.
- In the study, published in the journal Science, researchers at the ATR Computational Neuroscience Laboratories, in Kyoto, western Japan, used magnetic resonance imaging (MRI) scans to locate exactly which part of the brain was active during the first moments of sleep.
- The scientists then woke up the dreamers and asked them what images they had seen, a process that was repeated 200 times.
- These answers were compared with the brain maps that had been produced by the MRI scanner, the researchers said, adding that they later built a database, based on the results.
- On subsequent attempts they were able to predict what images the volunteers had seen with a 60 percent accuracy rate, rising to more than 70 percent with around 15 specific items including men, words, and books, they said.
"We have concluded that we successfully decoded some kinds of dreams with a distinctively high success rate," said Yukiyasu Kamitani, a senior researcher at the laboratories and head of the study team, on Friday.
"Dreams have fascinated people since ancient times, but their function and meaning have remained closed," Kamitani said. "I believe this result was a key step towards reading dreams more precisely."