Researchers use computers to probe minds in attempt to decode dreams
LOS ANGELES — Dreams defy even the dreamer, slipping away as stealthily as they arrive in a mind made credulous by sleep. But what if scientists could read our dreams by using the most advanced medical imaging machines and employing the sophisticated algorithms that flag fraudulent transactions among millions of credit card purchases?
Researchers in Japan have taken an early step toward this chimerical goal by training computers to recognize the images flitting through the minds of sleepers in the earliest stages of dreaming. Their results, published online Thursday by the journal Science, suggest that machines may be able to read our minds — at least while we're in the anteroom of dreamland.
“We're all intrinsically interested in dreaming, but neuroscientists to this day aren't certain what it does for us,” said Jack Gallant, who studies the brain's visual system at the University of California at Berkeley.
Like other researchers applying their brains to the brain, the Japanese scientists are probing dreams to understand how they relate to such core functions as memory consolidation and learning.
The researchers put three volunteers into a functional magnetic resonance imaging machine capable of tracking blood flow in the brain, a sign of neurons at work. They also hooked up the volunteers to electroencephalograph machines, which record the electrical activity of those neurons.
Then the scientists waited for the subjects to fall asleep.
The EEG readings showed when the volunteers entered an early stage of dreaming called hypnagogic hallucination. The researchers woke the subjects about 200 times, about every six minutes, to get verbal reports of what they “saw” before the images faded from memory.
The volunteers' responses were charted, and researchers focused on the nouns in these descriptions and combined them into generic categories, which were represented by images — a human face, a key, furniture — and presented to the subjects while awake.
The rest was a giant math problem. The scientists wrote a computer program to sort through the patterns of brain activity captured by the functional MRI in both waking and sleeping states; then the program looked for links between those brain activity patterns and specific images.
The computers learned to decode dream imagery with an average accuracy of 60 percent, according to the study. In some cases, the accuracy was significantly higher.
The fact that the computer models used data from waking minds and still made accurate predictions about dreams suggests the researchers are onto something about the links between waking and dreaming states, Gallant said.
“There's something in common between what goes on in dreaming and what goes on in perception,” he said.