De techniek die men in deze studie gebruikte kwam erop neer dat men de patiŽnt vroeg om een bepaald tafereel te visualiseren (bv. tennis spelen) als het antwoord op een gestelde vraag 'ja' was en een ander tafereel (wandelen) als het antwoord 'neen' was. Door na te gaan welke hersenzones daarbij actief waren (fMRI) kon men zo ahw. het antwoord aflezen op de scan.
Het was maar bij een klein aantal patiŽnten mogelijk om op deze wijze te communiceren, maar aangezien ťťn daarvan, de boven vermelde man, zich al sinds 2003 in een vegetatieve toestand bevond, is het toch een belangrijk resultaat.
Het toont aan dat patiŽnten in een vegetatieve toestand mogelijks toch nog over een bepaald niveau van bewustzijn en over een zekere mate van kennis kunnen beschikken...
Researchers in the UK and Belgium who scanned the brains of patients in a vegetative or minimally conscious state while they were asked to perform mental tasks found that some of them were able to control brain activity in a way that suggested signs of awareness and cognition, and in one case, the patient was even able to communicate "yes" and "no" via the brain scan....
For the study, they used functional magnetic resonance imaging (fMRI) to scan the brains of 54 patients for specific activation of blood-oxygenation- level-dependent responses to being asked to perform well-known mental imagery tasks.
The fMRI technique they used in this study was a further development of one they first used with a patient in a vegetative state in a study they published three years ago.
The results showed that:
* 5 of the patients were able wilfully to modulate their brain activity.
* 3 of the 5 patients revealed signs of awareness when they underwent further bedside tests.
* The remaining 2 patients, however, showed no voluntary behaviour that could be detected clinically.
* One of the 3 responsive patients was able to use the technique to answer "yes" or "no" to questions during the fMRI, however "it remained impossible to establish any form of communication at the bedside", wrote the authors.
The authors concluded the results show that:
"A small proportion of patients in a vegetative or minimally conscious state have brain activation reflecting some awareness and cognition."
The male patient at the centre of this study was in a road traffic accident in 2003 when he was 29 years old. He sustained a severe traumatic brain injury that left him physically unresponsive and doctors concluded he was in a vegetative state.
Using their latest fMRI method, Monti and colleagues mapped the patient's brain while they asked him to answer "yes" or "no" to questions like "Is your father's name Thomas?" The scan showed that the patient could wilfully change his brain activity to communicate his answers.
One of the methods they used in the study was to ask the patient to imagine doing something like "playing tennis" when the correct answer was spoken. The fMRI showed that patient's brain became active in the pre-motor cortex, the part that deals with movement...
"We were astonished when we saw the results of the patient's scan and that he was able to correctly answer the questions that were asked by simply changing his thoughts."
"Not only did these scans tell us that the patient was not in a vegetative state, but more importantly, for the first time in 5 years it provided the patient with a way of communicating his thoughts to the outside world," he added.
Co-author Dr Steven Laureys, a member of the team based at the University of LiŤge in Belgium said that so far the scans have been the only viable way to communicate with the patient since his accident.
"It's early days, but in the future we hope to develop this technique to allow some patients to express their feelings and thoughts, control their environment and increase their quality of life," said Laureys.
"Willful Modulation of Brain Activity in Disorders of Consciousness." Monti, Martin M., Vanhaudenhuyse, Audrey, Coleman, Martin R., Boly, Melanie, Pickard, John D., Tshibanda, Luaba, Owen, Adrian M., Laureys, Steven. N Engl J Med Published online 3 February 2010. (abstract)
Op deze Blog (Mind hacks) vind je nog wat bijkomende info.