A new device can enable people who are completely unable to speak or move to manage unscripted back-and-forth conversation.
Claimed as the first real-time, brain-scanning speller, the system builds on earlier uses of fMRI brain scans to assess consciousness in people described as being in an unconscious, vegetative state and to enable them to answer yes and no questions.
"The work of Adrian Owen and colleagues led me to wonder whether it might even become possible to use fMRI, mental tasks, and appropriate experimental designs to freely encode thoughts, letter-by-letter, and therewith enable back-and-forth communication in the absence of motor behavior," said Bettina Sorger of Maastricht University in The Netherlands.
Sorger's team came up with a letter-encoding technique that, they say, requires almost no pre-training. Participants can select letters on a screen, which guides the letter encoding.
For each specific character in the study, participants were asked to perform a particular mental task for a set period of time. That produced 27 distinct brain patterns corresponding to each letter of the alphabet and the equivalent of a space bar, which could be automatically decoded in real-time using new data analysis methods.
In each experiment, participants held a mini-conversation consisting of two open questions and answers. Everyone the researchers tested was able to successfully produce answers within a single one-hour session.
In the past, fMRI has only allowed people to answer the equivalent of multiple-choice questions.
Ultimately, says Sorger, her team's goal is to switch the new fMRI technology to a more portable and affordable method for measuring blood flow, such as functional near-infrared spectroscopy (fNIRS).