Universiteit Maastricht

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A conversation without speaking

29 June 2012

Researchers at Maastricht University develop fMRI-based spelling device

Researchers at Maastricht University (UM) have developed an instrument that may enable locked-in patients (people who are unable to speak, move or even blink their eyes because of complete paralysis) to have a conversation by forming words using just their brain signals. This is the first real-time fMRI-based spelling device. The study was published online yesterday in the international journal Current Biology.

The technology builds on the use of fMRI (functional magnetic resonance imaging) brain scans to discover whether people in a vegetative state show any degree of awareness and to enable them to communicate with yes/no responses. Dr Bettina Sorger of the Maastricht Faculty of Psychology and Neuroscience: ‘These possibilities made me wonder whether fMRI could be used to form letters by using cognitive tasks, and thus make communication possible without any form of motor movement.’

Sorger’s team devised a letter-encoding technique that requires almost no prior training. The healthy study participants were asked to perform a specific cognitive task for each letter that was displayed on a screen (e.g. reciting a poem, calculating a sum or mentally drawing a simple object). By varying the starting point and the duration of the task, 27 different brain patterns were produced (one for each letter of the alphabet and one for a ‘space’). The patterns were automatically decoded in real-time using newly developed data analysis methods.

Study participants used this communication method to have a mini-conversation with the researcher in which they were required to answer two open questions. All of the participants successfully produced answers during the one-hour sessions.

The results expanded the current uses of fMRI, which until now had made it possible for users to answer multiple choice questions with four different answers, but never to hold an actual conversation and answer open questions. Sorger: ‘With the help of this new method, people with complete paralysis who cannot benefit from other forms of alternative communication may be given the opportunity to formulate their thoughts and have conversations.’

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