Visual Imagery During Sleep Can be Detected and Decoded, Scientists Show

The process of dreaming is still a mystery and largely unknown, but a groundbreaking new brain imaging study probably answers one of the fundamental questions. Does our brain create the, often unreal, scenes we see in dreams in detail, or is it a more loose process based on fantasy in later thought processes? Researchers now developed and tested a dream interpretation program that could analyze a person's visual imagery during sleep, predicting objects in it with about 60 percent accuracy.

It will be a far way to machinations like seen in "Inception", but it seems to be at least theoretical possible. In this first stage, the dream decoder can only identify whether dreamers are seeing particular objects based on their previous brain scans, without any context like color, narrative, or emotion, said Yukiyasu Kamitani, one of the scientists at the Advanced Telecommunications Research Computational Laboratories in Kyoto.

The research, presented last year at the Society for Neuroscience conference and published today in the journal Science, is a major step towards understanding why and how we dream, and demonstrates that it is possible to use brain imaging for visual dream interpretation.

"We know almost nothing about the function of dreaming," Masako Tamaki, a neuroscientist at Brown University, told Livescience. "Using this method, we might be able to know more about the function of dreaming." Tamaki is a co-author of the study.

To get to these results, the research team measured the brain activity of three research subjects while they were asleep in a functional magnetic resonance imaging (fMRI) brain scanning machine and connected to electroencephalography (EEG) electrodes over the course of ten days.

During a dream session, the scientists woke them every few minutes when the EEG indicated that they were in a light stage of dreaming, in which it is easier to remember a dream, to then ask what they saw. By the end of that part of the experiment, each participant had been woken up 200 times to provide descriptions of their dream visualizations.

"Many of them were just about daily life in the office," Kamitani told NPR, and some were fantasies like dining with a Japanese movie star. Others were absurd or surreal:

"From the sky, I saw something like a bronze statue, a big bronze statue," one drowsy man told researchers when he was woken up from a dream. "The bronze statue existed on a small hill. Below the hill, there were houses, streets, and trees in an ordinary way."

The researchers then developed a visual imagery decoder that could find corresponding patterns in brain activity. Patterns were recorded from the men when they were awake and were watching a video that had hundreds of images, corresponding to dream scenes. That gave the computer dream interpretation model further context, enabling it to compare what brain regions were active while seeing particular images while sleeping and while awake.

In the last part of the experiment, participants slept and dreamed in an fMRI machine one last time. The machine dream interpretation model analyzed their brain activity during that session and, amazingly, predicted what objects they were visualizing 60 percent of the time -- a very high accuracy considering the infancy of such methods.

"This is probably the first real demonstration of the brain basis of dream content," said Dr. Robert Stickgold, a neuroscientist and dream expert from Harvard Medical School in Boston, who told the journal Science that the latest study on dreams was "stunning in its detail and success''.