When doctors suspect that a patient might be in a "vegetative" state following a serious brain injury, they run a plethora of tests to confirm the diagnosis. These usually consist of asking patients questions about their environment, and all are aimed at determining their level of consciousness. But contrary to what you might have seen on TV, the sorts of tests rarely include brain scans — ones performed through a machine called an fMRI — because they’re expensive, but more importantly, doctors still don’t quite know what to look for when analyzing someone's awareness through brain activity.

"Looking at brain activity just isn’t the standard of care," says Lorina Naci, a neuroscientist at the University of Western Ontario, in Canada. "And unfortunately patients with brain injuries are notoriously bad at answering questions," so doctors sometimes miss clues that they might have seen if they had used other methods.

That’s why Naci and her team are trying to develop a better way of testing consciousness in patients with brain injuries. And what they’ve come up with — a test that combines an Alfred Hitchcock TV show with an fMRI machine — isn’t just significant for the future of brain science. It’s also significant for one specific human being, as it allowed scientists to determine that a patient with an unknown levels of consciousness was in fact capable of understanding the events happening around him — even though his initial injury had taken place over 16 years ago, and he had been unresponsive since then.

"We show for the first time that a patient with unknown levels of consciousness was able to analyze and monitor information coming from his environment," says Naci, whose work on the patient was published today in Proceedings of the National Academy of Sciences.

In the study, Naci and her colleagues showed an eight-minute edit of Alfred Hitchcock’s "Bang! You’re dead" — a video that’s considered suspenseful and engaging — to 12 healthy participants, while monitoring their brain activity using an fMRI machine. Then, they repeated this experiment with two unconscious patients who had retained the ability to hold their eyes open for long periods of time. The first patient, Naci explains, had suffered a cardiac arrest after a blow to the chest 16 years ago, when he was 18 years old, whereas the second patient, a 20-year-old woman, suffered a brain injury of unknown origin about 10 years ago.

"All the healthy patients showed synchronized brain activity in the brain regions that are ... used as a proxy for awareness," Naci says. And so did the unresponsive male patient.

These findings alone weren’t enough to determine whether the patterns the researchers were seeing in the conscious participants and the unconscious patient indicated engagement and understanding of the frames being presented before him, however. It’s possible that the video might have been triggering the sensory parts of his brain. So, the researchers combined this experiment with two others aimed at determining which parts of the video were most demanding.

"In order to confirm our findings, we linked actual aspects of the movie to a whole new set of participants," Naci says. To do so, the researchers asked new participants to perform a task that would tell the researchers when the movie demanded their attention the most. "What individuals did in the lab, is they were asked to press a button continuously and every once in a while they had to stop pressing the button," all while watching the video. To do this, Naci explains, they had to monitor the their responses "so they would know when to inhibit them." Thus, the researchers were able to determine which parts of the video demanded the most attention from the participants based on how often they screwed up.

As expected, the findings from that experiment — in addition to a questionnaire based experiment — synced up with the fMRI study: the moments that produced the most errors in the button group matched the moments that caused synchronized brain activity in the fMRI participants.

And, just to be sure, the researchers repeated the experiment with the fMRI group using the a re-edited version of the Hitchcock video. "We created a movie that was completely scrambled by putting the frames in a random order with no detectable plot," Naci says. This still caused a certain amount of synchronized brain activity, the researchers say, but only in sensory parts of the brain — not those that allow us to focus and filter out distractions. "This was a big result for us," Naci says, because it showed that "the activity wasn’t just [the result] of some automatic triggering."

Russell Poldrack, a cognitive neuroscientist at Stanford University who didn’t participate the study, wrote in an email to The Verge that the main takeaway of this study is that there may be "big differences in the mental function of people who are labeled as 'vegetative.'’" With this in mind, the method developed by Naci and her colleagues might provide a "potentially powerful tool" for making those distinctions. "It is of course very difficult to make strong conclusions based on such a small sample of patients, and one would like to see it in a larger sample," he said. "But the results from the single patient who showed the effect look very robust to me."

For Naci, the most important aspect of this study are its implications for brain science. "There has been no attempt to qualify what is conscious of the brain activity we see through fMRIs," Naci says. So, this opens doors for being able to measure consciousness "in brain-injured patients or even in developmental consciousness, animal consciousness or patients under anesthesia."

But this study only showed this effect in a single patient. The woman didn’t show this synchronicity, so there’s a lot more work left to be done before the researchers can reach any firm conclusions. "We haven’t yet determined how often this happens," Naci says. "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."

For now, however, the people to whom this matters most are the male patient and his family. "We see different kinds of involvement from various families," Naci says. "But in this particular family, the father had been taking his son to the movies for many years, on a weekly basis," even though he had no way of knowing whether this was making a difference. So "it was reassuring to him that habit was indeed something that his son was understanding — something that he was benefiting from — and that he should keep doing."