In 2006 Dr Adrian Owen and his team made medical history.
They discovered a new realm of consciousness, somewhere between life and death, which they called the Grey Zone.
The people who inhabit it are frequently labelled as irretrievably lost, with no awareness or sense of self.
The shocking truth is that they are often still there, an intact mind trapped inside a broken body and brain, hearing everything around them, experiencing emotions, thoughts, pleasure and pain.
But now, through Dr Owen's pioneering techniques, we can talk to them - and they can talk back.