The stuff of dreams

Computers don’t dream — but they can help us understand how we do.

In a recent experiment, a computer program successfully identified some contents of people’s dreams. The program compared people’s brain activity when they were both awake and asleep. It identified that seeing a certain object produced a particular pattern of brain activity. And it found that pattern was similar for an object whether it was seen in waking life or dreamy slumber.

Neuroscientist Yukiyasu Kamitani led the experiment. He works at the Advanced Telecommunications Research Institute International in Kyoto, Japan. A study detailing the experiment was published in Science during April.

The new results are “striking,” says neuroscientist Frank Tong, of Vanderbilt University in Nashville. Tong told Science News that the experiment shows “brain activity during dreaming is very similar to activity during wakefulness.”

Neuroscientists like Tong and those who conducted the new study want to understand how our brains produce the images we see in a dream. Scientists have only a slight understanding of this, Tong says. The new study adds to that knowledge. Comparing sleeping and waking brain activity could also help scientists understand other brain states, such as those of people in a coma.

Dreams aren’t easy to study. Previous experiments on mice have helped scientists understand some aspects of dreaming, such as how memories are formed. These studies can go only so far — after all, mice can’t describe their dreams to researchers.

Dream experiments on people are limited, too. The dream-filled part of adult sleep takes 90 minutes to kick in. So researchers have to settle in and wait. And the machine they use to scan participants’ brains — called an fMRI — is noisy. It can prevent some people from falling asleep.

Kamitani and his coworkers found a different way to study dreams. They cut out the wait by recording the brain activity of people in the early stages of sleep.

Their experiment involved three adult males who volunteered to sleep for science. The participants were in for a rough night.

The scientists recorded the brain activity of the men as they fell asleep in an fMRI. Shortly after the volunteers dozed off, the researchers awakened them. Each time, the men had to describe what they had just seen in their dreams. The scientists took careful notes of the volunteers’ descriptions. Over and over, the volunteers fell asleep for a short while before being woken up and asked to describe their dreams.

Later, the scientists asked the same volunteers to look at images while awake. Their brain activity was recorded during this exercise, too. Some of the pictures showed objects the participants had reported seeing in their dreams.

The scientists then added the new brain activity data — along with the corresponding images — to the computer program. At this point, the program analyzed both waking and sleeping data. It then linked certain patterns in brain activity to particular images. Using those links, the program analyzed a sleeping patient’s brain activity. More often than not, the program correctly picked which of two objects had appeared in a dream — for example, a girl and not a book.

Kamitani says the study suggests that the brain experiences real and dreamed images in similar ways. So if seeing is believing, then the brain is giving us another good reason to believe in our dreams.

Discovering if the brain experiences dreamed sounds and emotions in the same way will require more studies in the future.

Power Words

neuroscience Any of the sciences that deal with the structure or function of the nervous system and brain.

fMRI (functional magnetic resonance imaging) A special type of machine used to study brain activity. It uses a strong magnetic field to monitor blood flow in the brain. Tracking the movement of blood can tell researchers which brain regions are active.