A man who was diagnosed to be in a vegetative state for nearly two decades was found capable of following the plot of a 1961 episode of the Alfred Hitchcock Presents suggesting consciousness in a patient believed to be entirely unresponsive following a violent incident that deprived his brain of oxygen 16 years ago.

In an experiment described in a study published in the journal Proceedings of the National Academy of Sciences (PNAS) on Sept. 15, Adrian Owen, from The Brain and Mind Institute of The University of Western Ontario, and colleagues asked one dozen volunteers to watch an engaging Hitchcock thriller "Bang! You're dead," which was shortened to eight minutes.

The researchers monitored the brain activities of the participants using a functional magnetic resonance imaging (fMRI) machine while they watched the video and then repeated this with two nonresponsive patients who can open their eyes for a long time. The first patient was 18 years old when he lost consciousness after being assaulted 16 years ago and the second one is a 20-year old who had brain injury about a decade ago.

Owen and colleagues found that the first patient showed similar patterns of brain activities in the areas of the brain associated with higher cognition and the processing of sensory information to those of the healthy volunteers suggesting that he may have actually understood and followed the plot of the film.

"What we saw is that his brain changed at all of those key moments in the movie in exactly the same way as a healthy volunteer," Owen said. "Essentially we were getting at consciousness. We were measuring or detecting the fact that this patient was able to follow the plot."

The researchers said that their study has implications on understanding consciousness particularly in unresponsive patients who cannot speak and show willful behavior to express their conscious experiences.

"This approach provided strong evidence for intact conscious experiences in a brain-injured patient who had remained behaviorally nonresponsive for 16 y," the researchers wrote in their study. "These findings shed light on the common basis of human consciousness and enable the interpretation of conscious experience in the absence of behavior."

Owen and colleagues, however, admitted that there is still more work to be done since the second patient did not exhibit the same brain activity as the first patient.

"We haven't yet determined how often this happens," study researcher Lorina Naci, also from The Brain and Mind Institute, said. "So our next step is to look at that in a number of brain-injured patients, and to figure out how frequently they show this type of activity."