Oct 212012

People unable to speak through paralysis may one day be able to spell out their thoughts with technology being developed by Dutch scientists. The brain-scanner measures different levels of brain activity and associates each level with a letter of the alphabet. Jim Drury reports.

It’s a brain scan with a difference – one that could enable completely paralysed patients to communicate verbally. Maastricht University scientists proved it’s possible to partially read minds by measuring brain activities associated with individual letters. Neuroscientist Bettina Sorger came up with the idea, which she calls ‘letter decoding’. Sorger assigned volunteers like Thomas different mind tasks so they could map out their own individual alphabet. (SOUNDBITE (English), NEUROSCIENTIST, BETTINA SORGER, SAYING: “We put two things together: the first thing is what the subject is doing and the other is when the subject is doing it, so we have possibility to combine nine different time periods with three different mental tasks, put this together we have 27 different brain activations that we can robustly initiate and this we can use to allocate this to 27 different information units, like 26 letters and the blank space.” The participant must imagine three different scenarios: drawing geometrical objects, counting numbers, and reciting a poem, depending on which letter appears highlighted on screen. The 27 different brain responses are then assigned and the subject can spell out words. UPSOT: NEUROSCIENTIST, BETTINA SORGER, SAYING: “Okay, Thomas, now, I would like to ask you the first question: the question is ‘what is your favourite music genre?'” UPSOT: NEUROSCIENTIST, BETTINA SORGER, SAYING: “Now we know that you prefer rock music, I would like to ask you now: ‘what is your favourite rock band?'” Sorger says it isn’t mind reading as such, because the subject has to actively participate in the test. SOUNDBITE (English), NEUROSCIENTIST, BETTINA SORGER, SAYING: “It’s not possible yet to think of a letter, for example A and then letter B, that we can disentangle the brain activation that is certainly produced when you think of these two letters, but the differences of brain activation are so subtle that we cannot differentiate this, so we have kind of found a circumvention for that and this is that we let the subject voluntary produce brain activation patterns that we can later differentiate.” Sorger says her team’s research is at present a proof of concept. The next stage is performing clinical trials with real patients, to increase accuracy and decrease the time needed to encode letters. Eventually she hopes paralysed patients will be able to communicate at home, rather than travel to use a hospital brain scanner. With further development, Sorger believes ‘letter decoding’ could give a voice to the severely disabled world-wide.

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