TORONTO, Feb. 11, 2009 – A team of researchers at Bloorview Kids Rehab, Canada’s largest children’s rehabilitation hospital, has used optical brain imaging to develop a technique for decoding the preferences of those who cannot speak or move. The purpose of the method is to determine the choice of disabled children, with the goal of ultimately opening the world of options.
By measuring the intensity of near-IR light absorbed in brain tissue, Bloorview scientists have demonstrated with 80 percent accuracy a person’s preference for one of two drinks.
“This is the first system that decodes preference naturally from spontaneous thoughts,” says Sheena Luu, the University of Toronto biomedical engineering student who led the study under the supervision of Tom Chau, who is chairman of pediatric rehabilitation engineering for Canada Research.
Most brain-computer interfaces designed to read thoughts require training. For example, to indicate yes to a question, the person needs to perform an unrelated mental task – such as singing a song in his head.
The nine adults in Luu’s study received no training. Prior to the study, they rated eight drinks on a scale of one to five.
Wearing a headband fitted with fiber optics that emit light into the brain’s prefrontal cortex, they were shown two drinks on a computer monitor, one after the other, and asked to make a mental decision about which they liked more.
“When your brain is active, the oxygen in your blood increases, and depending on the concentration, it absorbs more or less light,” Luu said. “In some people, their brains are more active when they don’t like something, and in some people, they’re more active when they do like something.”
After teaching the computer to recognize the unique pattern of brain activity associated with each subject’s preference, the researchers accurately predicted 80 percent of the time which drink the participants liked better.
“Preference is the basis for everyday decisions,” said Luu. When children with disabilities can’t speak or gesture to control their environment, they may develop a learned helplessness that impedes development.
In the future, Luu envisions creating a portable near-IR sensor that rests on the forehead and relies on wireless technology to offer choices to children who can’t speak or move.
Her work is part of Chau’s body-talk research, which aims to give children who are “locked in” by disability a way to express themselves through subtle body processes like breathing pattern, heart rate and brain activity.
Luu notes that the brain is too complex ever to allow decoding of a person’s random thoughts. “However, if we limit the context – limit the question and available answers, as we have with predicting preference – then mind-reading becomes possible.”
This study was published in the February Journal of Neural Engineering.
For more information, visit: www.utoronto.ca or www.bloorview.ca