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Brain scanner may help "locked in" people communicate

posted 18 Sep 2012, 06:16 by Mpelembe Admin   [ updated 18 Sep 2012, 06:16 ]

People unable to speak through paralysis may, before too long, 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.

MAASTRICHT, THE NETHERLANDS (RECENT) (REUTERS) - Scientists at Maastricht University in the Netherlands have proved it is possible to partially read the mind of someone who wants to communicate their thoughts by measuring brain activity associated with letters of the alphabet.

The research is the brain child of neoroscientist Bettina Sorger, who prefers to call it 'letter decoding' instead of mind reading, because the active mental participation and compliance of the subject attached to the brain scanner are necessary.

"This is a proof of concept study with healthy participants, we have not scanned any patient yet, it's the next step, and we don't do mind reading, so we cannot read the thoughts of others, we do letter decoding in an indirect way and we are depending on the compliance of the participant, so we cannot just read out the thoughts of someone," Sorger told Reuters.

Since current technology cannot yet record subtle differences in brain activities associated for each letter of alphabet, Bettina says she has found a way around it by assigning different mind tasks to different letters.

"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," she said.

Patients are asked to perform one of three mental tasks, each of which is paired with one of three rows of letters on a screen. The three mental tasks are motor imagery (imagining drawing geometrical objects), mental calculation (imagining counting numbers) and inner speech (imagining reciting a poem). In order to spell out a word, the patient waits for each letter to be highlighted on the screen before performing the mental task that applies to the row in which it appears. Gradually, the word forms. A test patient was able to tell Dr Sorger that his favourite music genre was "rock" and that his favourite band was "AC/DC".

By highlighting each letter for a different period of time, Bettina receives 27 different brain responses which she assigns to the letters of the English alphabet.

"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," Sorger told Reuters.

The next task for Sorger and her team is to perform clinical trials with patients, to increase accuracy and decrease the time necessary for encoding each letter. The final goal is to enable paralysed patients to communicate with their environment from home, without having to travel to a hospital to use a brain scanner.

Sorger is also working on using other modalities for guidance, such as hearing or touch, so people who cannot use their eyes can still use this tool to communicate with their environment.