Researchers say vegetative brain-injury patients may be more conscious than previously realized.
In a new study, scientists used MRI brain scans to evaluate 54 unresponsive patients.
The researchers asked them to imagine certain scenarios such as navigating their hometown streets or playing tennis.
The activity triggered brain activation in five of the patients. The other 49 patients showed no signs of consciousness on their scans.
One of the study's authors, Martin Monti, is with the Medical Research Council Cognitive and Brain Sciences Unit in Cambridge, England. He marveled over the case of a 29-year-old patient who was able to answer yes-or-no questions by envisioning certain scenes doctors asked him to imagine.
"We were stunned when this happened," Martin said. "I find it literally amazing. This was a patient who was believed to be vegetative for five years."
Experts say the findings highlight the difficulty of accurately evaluating people with severe brain damage.
The study, authored by researchers in Britain and Germany, was published online Wednesday by the New England Journal of Medicine.