Mind Reading with Functional MRI

Scientists can accurately predict which of a thousand pictures a person is looking at by analyzing brain activity using functional magnetic resonance imaging (fMRI) which is a brain imaging method that detects blood flow in the brain, giving an indirect measure of brain activity.

According to the study, published in the the journal Nature, scientists first gathered information about how the brain processes images by recording activity in the visual cortex as subjects looked at several thousand randomly selected pictures. Neurons in this part of the brain respond to specific aspects of the visual scene, such as a patch of strongly contrasting light and dark, so the activity recorded in each area of the brain scan reflects the visual information being processed by neurons in that area of the brain. The researchers compiled this information to develop a computer model that would predict the pattern of brain activity triggered by any image.

When volunteers were later shown a new image not included in the first set, the computer model was able to correctly predict which picture out of 120 or 1,000 possibilities the person looked at with 90 or 80 percent accuracy, respectively.

"They can do this with a surprising degree of accuracy," says Frank Tong, a neuroscientist at Vanderbilt University, in Nashville, TN, who was not involved in the research. "People will be struck by how much visual information these researchers were able to extract from the brain."

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