British scientists said they could communicate with a patient who has not shown any sign of outward consciousness for five years.
They used a new brain scanning technique to 'talk' to the 29 year old Belgian man who damaged his brain in a car accident and has been classified as being in a vegetative state.
The patient was able to communicate "yes" and "no" using just his thoughts during a research conducted by a team from Cambridge University.
The study was published in the New England Journal of Medicine.
Dr Adrian Owen, who led the team, said this is a rare case.
The research raises many ethical issues including whether or not to allow patients in a permanent vegetative state to die by withdrawing all treatment.
Dr Ranaan Gillon is professor of medical ethics at Imperial College in London.
Someone who knows how it feels to be awake, but unable to communicate, is the Daily Telegraph's Jeffrey Lean.
The journalist was in a coma for a month after an operation went wrong.
First broadcast 4 February 2010