Washington ? Advanced brain scanning uncovered startling signs of awareness in a woman in a vegetative state, British scientists reported Thursday – a finding that complicates one of medicine’s ethical minefields.

The work is sure to elicit pleas from families desperate to know if loved ones deemed beyond medical help have brain activity that doctors don’t suspect. “Can he or she hear and understand me?” is a universal question.

It’s far too soon to raise hopes, the British researchers and U.S. brain specialists stress. There’s no way to know if this 23-year-old woman, brain-damaged more than a year ago, will recover, and therefore if her brain activity meant anything medically. Her brain injury may not be typical of patients in a vegetative state.

Scientists don’t even agree on whether the woman had some real awareness – she seemed to follow, mentally, certain commands – or if her brain was responding more automatically to speech.

“This is just one patient. The result in one patient does not tell us whether any other patient will show similar results, nor whether this result will have any bearing on her,” cautioned neuroscientist Adrian Owen of Britain’s Medical Research Council. He led the novel brain-scanning experiment, reported in the journal Science.

The work does raise calls for more research in this difficult-to-study population – because of the tantalizing prospect of one day learning how to predict whose brain is more likely to recover, and maybe even tailoring rehabilitation.

“It raises the questions of ethics and experience of these patients, I think, to a new level,” said neuroscientist Joy Hirsch of New York’s Columbia University Medical Center. “It raises the tension about how we treat these patients.”

But, “making medical decisions based on this information at this point in time we say is not appropriate,” warned Hirsch, who is conducting similar research and already receives “just heartwrenching” requests for help.

The woman was injured in a car crash. By the time Owen scanned her brain five months later, she had been pronounced in a vegetative state – physically unresponsive to a battery of tests. A small percentage of people make some recovery after a short period in a vegetative state.

Those who don’t improve after a longer period are classified as in a “persistent vegetative state,” such as the late Terri Schiavo, who became a subject of political controversy over the question of taking such patients off life support. An autopsy showed she had irreversible brain damage.