London, March 6 : Scientists at the University of California in Berkeley have developed a mind-reading technique that could allow them to crack your mind's internal code and even predict what you're looking at based on your thoughts.
The technique, based on functional magnetic resonance imaging (fMRI), could shed light on how the brain processes visual information, and it might one day be used to reconstruct dreams, according to the researchers.
"[The research] suggests that fMRI-based measurements of brain activity contain much more information about underlying neural processes than has previously been appreciated," Nature quoted Jack Gallant, a neuroscientist at the University of California, Berkeley, and senior author of the study, as saying.
fMRI detects blood flow in the brain, giving an indirect measure of brain activity. Most fMRI studies to date have used the technology to identify the parts of the brain involved in different cognitive tasks, such as reading or remembering faces.
However, the new study has adopted an up-and-coming trend in fMRI i.e. using the technology to analyse neural information processing.
For the study, 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.
The next step is to interpret what a person is seeing without having to select from a set of known images, Gallant said.
"That is in principle a much harder problem," says Gallant.
A decoding device that can read out the brain's activity could be used in medicine to gauge the results of a stroke or the effect of a particular drug treatment, or to help diagnose conditions such as dementia, by seeing how the function of the brain changes as a result of illness or intervention.
Gallant and his team plan to use this technology to better understand how the visual system works by building computational models of various theories and then testing their ability to interpret brain scans.
The study is published in the journal Nature.