Leading Edge / Summer 2009
Mind Reader

An infrared ray may help caregivers decode the wishes of people with severe paralysis


Tom Chau is a modern-day mind reader. Ensconced in a lab at Bloorview Kids Rehab in Toronto, Chau – a clinical engineer and senior research scientist – is designing a technology that uses infrared light to decode the wishes of children with “locked-in syndrome.” The rare condition received a wallop of public attention in 2007 with the release of The Diving Bell and the Butterfly, a film based on a memoir by Jean-Dominique Bauby,  a journalist and editor in France. After suffering a major stroke, Bauby wrote the book using only the movement of one eye.

Chau says there are hundreds of thousands of people around the world who have survived a condition such as a brain stem stroke, a brain tumour or severe cerebral palsy, but have virtually no ability to communicate beyond very minimal muscular function, such as moving their eyes up and down. “In lots of cases,” he says, “we can’t confirm what they can hear or see.”

Chau has developed a technique that uses infrared light to measure blood flow in the frontal lobe, a region of the brain associated with decision-making. The light is directed at the person’s forehead using fibre-optic wires on a headband. The wavelength Chau uses penetrates the skull to a depth of about 1.5 centimetres – far enough, he says, to reach the brain’s surface.

The device is calibrated to measure the amount of infrared light that’s absorbed by oxygenated and deoxygenated hemoglobin. A change in oxygenated hemoglobin is evidence of heightened brain activity in response to visual or auditory stimuli. Chau and his team have worked with nine able-bodied adults to determine if they can detect preferences for different types of drinks by gauging this kind of blood movement. Initial tests have distinguished a resting brain from one that’s making a choice, he explains. “Most of the communications with these individuals is framed as a yes or no question.”

While his work is still in the early development stage, Chau is looking to expand the scope of the project with new research grants and more subjects (he’s already got a long list of volunteers). Ultimately, Chau says, the goal is finding a way to allow these individuals to “consciously modulate their brain activity” so their thoughts can activate computerized devices, such as keyboards. “Ideally, if I were thinking ‘A,’ it would type an ‘A.’” The technology “can allow individuals to direct their own care and improve their basic quality of life.”


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