Signs of consciousness have been detected in three people previously thought to be in a vegetative state, with the help of a cheap, portable device that can be used at the bedside.
"There's a man here who technically meets all the internationally agreed criteria for being in a vegetative state, yet he can generate 200 responses [to direct commands] with his brain," says Adrian Owen of the University of Western Ontario. "Clearly this guy is not in a true vegetative state. He's probably as conscious as you or I are."
In 2005, Owen's team, used functional MRI to show consciousness in a person who was in a persistent vegetative state, also known as wakeful unconsciousness – where the body still functions but the mind is unresponsive – for the first time. However, fMRI is costly and time-consuming, so his team set about searching for simple and cost-effective solutions for making bedside diagnoses of PVS. Now, they have devised a test that uses the relatively inexpensive and widely available electroencephalogram (EEG).
In three of the people with PVS, brain regions known to be associated with those tasks lit up with activity, despite physical unresponsiveness. This suggested to the researchers that the subjects were carrying out a complex set of cognitive functions including hearing the command, understanding language, sustaining attention and tapping into working memory.
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