The state-of-the-art brain scans that allowed doctors to look inside the head of former Israeli prime minister Ariel Sharon show how advances in neuroscience are forcing a rethink of what it means to be in a long-term coma.

Neurologists who performed the tests said they hinted that Sharon, who has been in a coma since suffering a stroke in 2006, may have a degree of consciousness and be able to hear sounds or make out pictures.

“It’s encouraging to find these signs because it opens up the possibility of some meaningful communication,” said Paul Matthews, a professor of neurology at Imperial College London.

Until recently, he said, it had been assumed that many comatose patients diagnosed as being in a “vegetative state” had no meaningful awareness of their surroundings.

Yet progress in the use of functional magnetic resonance imaging (fMRI) scanners – machines that measure brain activity by detecting changes in blood flow – and in reading the signals they give has begun to change that view.

Compared with other “vegetative state” patients who have had similar tests and been described in scientific papers, Sharon’s responses were very faint, said Martin Monti, a cognitive psychologist from the University of California Los Angeles, who co-led the American-Israeli team that scanned Sharon’s brain.

There is little or no likelihood of a rapid recovery by Sharon, a former general, hawkish defense chief and leader of the right-wing Likud party who suffered his stroke weeks after leaving Likud to found a centrist group to pursue peace with the Palestinians.

But with more tests and research to devise a way for him to signal whether he is processing external information, it is possible that he, like others, could one day respond to questions about his state of mind and whether he is in pain.

“If it turns out that these signals are more robust, then there’s no doubt that we could use things like brain-computer interfaces (to communicate),” Monti told Reuters in an interview as he travelled from Israel back to the United States.