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22· Science&Technology

‘Brain dead’?

Maren Urner askswhat brain activity in the case of vegetative state patients tells us and explores the dilemmas surrounding howwe definewhat it is to be conscious

Consciousness is considered as the “holy grail” in neuroscience. The question is not only a philosophical one, but relates tomedical and daily life decisions: Whom to attribute consciousness to and what are nec- essary conditions for it? Verbal com- munication is certainly a bad guess, since you would deny that babies and deaf people are conscious.

ness without detectable awareness. Scientists all over the world try to es- tablish means to communicate with these patients in whatever possible manner. Three weeks ago the BBC claimed that “scientists have been able to reach into themind of a brain- damagedman and communicate with his thoughts”. In fact,MartinM.Monti, PhD, of

Towhomcan we attribute consciousness

-what are the necessary conditions for it?

Patients in a persistent vegetative

state are patients that had been in coma due to severe brain damage, but then progressed to a state of wakeful-

the UK Medical Research Council, and colleagues, reported in The New England Journal of Medicine that they have been able to record brain activity, which was wilfully modu- lated by five out of 54 patients (23 which were diagnosed as being in a vegetative state and 31 being in a minimally conscious state; among the five responders one was diagnoses as being minimally consciousness). In order to measure possible men-

tal stages in the patients, they used functional magnetic resonance imag- ing (fMRI). This is a technique which is used extensively by neuroscientists and indirectly measures immediate brain activity via the amount of de- oxygenation in the blood running through the brain. More precisely, the patients were

placed in an MRI scanner and asked to either imagine playing tennis or imagine navigating through a famil- iar roomor driving through a familiar neighbourhood. Control tests with healthy people have shown that these

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tasks activate different brain regions. Interestingly, one patient was able to actually communicate via the fMRI measurements:He was able to answer five out of six questions correctly with “yes” by imaging to play tennis or “no” by imaging to navigate. Impor- tantly, only patients who suffered physical head injuries are among the five who showed responses at all, and three out of the five were indeed able to physically move when tested at their bedside. The study heated up the discus-

sion about consciousness among sci- entists and laymen in a comparable manner. The most important ques- tion for relatives of a person in a veg- etative state is, “Are you there?” Relating this question to the study of Monti and colleagues this question might be rephrased to: “Does the ability to respond to five out of six

Themost important question for relatives of a person in a vegetative state is “Are

you there?”

Sources

Original paper: http://content.nejm.org/cgi/content/abstract/362/7/579 http://news.bbc.co.uk/1/hi/health/8497148.stm http://www.webmd.com/brain/news/20100203/vegetative-patients-talk-with-brain?page=2 http://www.medpagetoday.com/Neurology/GeneralNeurology/18283

highly overlearned autobiographical questions via brain activity imply that a person is aware?” According to Mark A. Brooks, PhD, neuropsychol- ogist, the answer is no. "Awareness is the functional totality of all cognitive skills - the sum of arousal, orienta- tion, attention, perception, memory, and reasoning”, he said. Whatever implications the results

– and follow-up studies possibly repli- cating the results – will have, “the findings primarily underscore the limitations of current categorisations for diminished states of conscious- ness”, Alan Faden, MD at the Uni- versity of Maryland School of Medicine in Baltimore, said in an email. Improved technology requires - not only - doctors to modify (diag- nostic) categories for what is called consciousness and diminished states of consciousness. Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28
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