Researchers at ATR's Computational Neuroscience Laboratories in Kyoto, Japan, have developed a way to relate brain scans to specific images, thus being able to effectively see what a person is dreaming about.
Led by Yukiyasu Kamitani, head of the Laboratories' department of neuroinformatics, the team tested three people while they slept, using functional magnetic resonance imaging (fMRI) scans of bloodflow to detect which areas of their brain were active and taking electroencephalogram (EEG) readings of their brain waves. They woke the test subjects whenever their brain activity suggested that they were dreaming, asked what they were dreaming about, and then let them go back to sleep. Doing this in three-hour blocks allowed them to get around 200 dream reports, according to the Scientific American article.
They then gathered together images using the key words that appeared most often in the reports and scanned the awake subjects' brains again while they viewed these images.
The researchers analyzed the activity in the brain associated with the earliest stages of visual processing, using methods of decoding which Kamitani and his associates developed back in 2008, and compared the data to what they has read from the subjects just before they were woken up.
"We built a model to predict whether each category of content was present in the dreams," said Kamitani, according to Scientific American. "By analyzing the brain activity during the nine seconds before we woke the subjects, we could predict whether a man is in the dream or not, for instance, with an accuracy of 75—80 per cent."
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Kamitani presented the group's findings earlier this week, at the annual meeting of the Society for Neuroscience in New Orleans.
"This is an interesting and exciting piece of work," says Jack Gallant, professor of psychology and researcher in systems and computational neuroscience at the University of California, Berkeley. "It suggests that dreaming involves some of the same higher level visual brain areas that are involved in visual imagery. It also seems to suggest that our recall of dreams is based on short-term memory, because dream decoding was most accurate in the tens of seconds before waking."
The next step in the research, according to Kamitani, is to try collecting the same data while a person is in REM (rapid eye movement) sleep, when most dreaming occurs.
"This is more challenging because we have to wait at least one hour before sleeping subjects reach that stage," he said, but indicated that the benefits outweighed the extra effort.
"Knowing more about the content of dreams and how it relates to brain activity may help us to understand the function of dreaming."
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