Some patients who fall into a coma are aware of their surroundings even though they can't communicate with others, and now scientists have found a new way to help identify them.
Scientists still don't fully understand how the brain activity gives rise to consciousness, but have been able to find differences between a conscious brain and an unconscious one. Those insights are helping researchers design tests for the minority of comatose patients who may be "aware" but who are unable to show it, the LiveScience Website reports.
For the latest study, medical investigators tracked 32 comatose patients and 26 healthy people. Some of the comatose patients displayed some awareness of their surroundings (by following simple commands, such as squeezing a finger, for instance). But others were diagnosed as in a "persistent vegetative state," meaning they had lost all conscious awareness.
The researchers examined participants' brain waves using electroencephalography (EEG) and identified patterns that allowed them to compare comatose patients' brains with those of healthy people.
The results showed brains of healthy conscious people had "rich and diversely connected networks," lacking in the comatose patients' brains, the researchers said. But some comatose patients who were thought to be completely vegetative actually showed some patterns similar to those of healthy people, suggesting they may have some level of awareness.
For example, brain imaging showed that when they were told to imagine doing a physical activity, such as playing tennis, the area of the brain responsible for controlling movement, lit up.
"Some vegetative patients who show signs of hidden awareness have remarkably well-preserved networks similar to healthy adults," the researchers wrote.
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