October 28, 2012
Brain Scans Used To Determine Content Of Dreams
redOrbit Staff & Wire Reports - Your Universe Online
Can't remember what you dreamt about last night? Never fear, because a team of Japanese researchers has reportedly discovered a way to determine what thoughts are going through a person's mind about while they sleep.Yukiyasu Kamitani, a member of the ATR Computational Neuroscience Laboratories in Kyoto, and colleagues recruited three male volunteers and monitored them while they slept, using electroencephalography to record their brain waves and studying the results in search of "changes in activity which could be related to the content of their dreams," explained Telegraph Science Correspondent Nick Collins.
When the researchers detected changes in the brain waves of the subjects -- a sign that they had started dreaming -- they woke up the subject and asked him what he had been dreaming about. The subject was then allowed to return to sleep. The process was repeated between seven to 10 times per day, in three-hour blocks, for each participant, Mo Costandi of Nature added.
The researchers compiled approximately 200 dream-related reports from their volunteers, he added.
"Researchers reported that while some of the dreams were out of the ordinary — for example a discussion with a famous actor — most involved more mundane experiences from everyday life," Collins said. "From the dream accounts they picked out 20 of the most commonly occurring themes, such as 'car', 'man', 'woman' and 'computer', and gathered pictures which represented each category."
"The participants were then asked to view the images while their brains were scanned a second time," he added. "By comparing the second set of brain activity data with the recordings made just before the volunteers had been woken up, the researchers were able to identify distinctive patterns in three key brain regions which help us process what our eyes see. They also found that activity in a number of other brain regions with more specialized roles in visual processing, for example in helping us recognize objects, varied depending on the content of the dreams."
Those three brain areas -- V1, V2, and V3 -- are involved in the primary stages of visual processing, Costandi explained. They encode contrast, edge orientation, and other essential features of visual scenes.
Four years ago, Kamitani and his associates reported that they had figured out a way to decode the brain activity linked to the earliest stages of visual processing, and used that information to recreate images that they then showed to volunteers, the Nature writer said. Now, they've built upon those findings and adapted them to dreams.
Their work was presented earlier this month at the Society for Neuroscience's annual meeting, held this year in New Orleans.
"We built a model to predict whether each category of content was present in the dreams," Kamitani told Costandi. "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%."
"This is an interesting and exciting piece of work. It suggests that dreaming involves some of the same higher level visual brain areas that are involved in visual imagery," added University of California, Berkeley, neuroscientist Jack Gallant, who was not involved in the study. “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.” he adds.