SCIENTISTS have reached into the shuttered world of a "lost" brain-damaged patient and communicated with him via his thoughts.
The 29-year-old Belgian was able to answer "yes" and "no" to questions by conjuring up imaginary scenes while having his brain scanned.
Before the extraordinary experiment, the man, who suffered a severe head injury in a road accident in 2003, had shown no sign of being aware of the outside world.
Five years ago, he was presumed to have slipped from a coma to a vegetative state, leaving his body functioning but his personality and consciousness wiped out.
The British and Belgian researchers now know that the diagnosis was wrong. The man was able to respond to questions about his life as scientists monitored activity in his brain.
They admitted to being "astonished" by the result, which has enormous implications for the care and treatment of vegetative patients.
The man was one of 23 patients diagnosed as being in a vegetative state and recruited for a three-year study by Medical Research Council (MRC) scientists in Cambridge and colleagues from the University of Lige in Belgium.
Its aim was to see if brainscans could detect signs of awareness in patients who were thought to be closed off from the world.
Functional magnetic resonance scanning (fMRI) was used to measure activity in "motor" and "spatial" brain regions while the patients were asked to imagine specific scenes.
The scans use magnetic fields and radiowaves to detect surges of bloodflow that accompany neural activity.
For the "motor" task, patients were asked to imagine standing still on a tennis court and swinging an arm to return balls from an instructor. To activate the "spatial" region, they had to imagine navigating the streets of a familiar city or walking from room to room in their home.
In four cases, the scans were able to detect activity in the appropriate brain region as the patients carried out the scientists' verbal instructions.
But one Lige patient who had produced reliable responses was singled out for an even more remarkable test. He was asked to use "motor" or "spatial" imagery as "yes" and "no" answers to questions. The patient responded accurately to five out of six autobiographical questions posed by the scientists.
On one occasion he was asked "Is your father's name Alexander?" and correctly answered "Yes" by imagining the tennis scene. When he was asked "Is your father's name Thomas?", he answered "No" by thinking about roaming streets or walking around the house.
However, when the sixth question was asked, virtually no activity was seen in either brain region. The scientists believe the patient had either fallen asleep or simply failed to hear the question.
Dr Adrian Owen, whose team developed the technique at the MRC Cognition and Brain Sciences Unit, Cambridge, said: "We were astonished when we saw the results of the patient's scan and that he was able to correctly answer questions that were asked by simply changing his thoughts.
"Not only did these scans tell us that the patient was not in a vegetative state but, more importantly, for the first time in five years, it provided the patient with a way of communicating his thoughts to the outside world."
The study was published in the New England Journal of Medicine.