In 1997, a teenage boy got kicked in the chest during a fight. The blow to his heart cut off blood supply to his brain, and after he had spent 3 weeks in a coma, doctors proclaimed him to be in a vegetative state—though his eyes were sometimes open, he appeared to be completely unaware of himself or his surroundings. But years later, with the help of a suspenseful TV clip directed by Alfred Hitchcock, researchers say they’ve detected glimmers of consciousness in the now–35-year-old man.
Few reliable tools exist for detecting neural signals of awareness in people who appear unresponsive, says Lorina Naci, a neuroscientist at the University of Western Ontario in London, Canada, and lead author of the new study. Over the past decade, her Western University colleague Adrian Owen has demonstrated that it is occasionally possible to detect awareness in unresponsive individuals by asking them to follow commands, such as to imagine playing tennis, while measuring their brain activity in a functional magnetic resonance imaging (fMRI) machine. Still, such methods are limited by the “notorious” difficulty that brain-damaged people have following instructions and paying attention, Naci says.
So she and Owen decided to try screening for consciousness with an activity that doesn’t require much effort: watching television. To ensure that it would be easy for patients to pay attention, they chose an episode of the TV series Alfred Hitchcock Presents called “Bang! You’re Dead.” The abridged, 8-minute episode has a simple, suspenseful plot, Naci says: A young boy with a toy gun finds his uncle’s loaded revolver and plays at shooting people, not understanding that the gun is real. For viewers, who know that some of the gun’s chambers contain bullets, “there are very tense moments” when the boy points the gun at his mother and a little girl in the supermarket, she says.
First, the researchers needed to determine how a healthy brain would respond to the episode, so they recruited 12 volunteers to watch the clip inside an fMRI scanner. During the moments of greatest suspense, activity in the frontal parietal brain regions, which are devoted to orchestrating attention, flared up in healthy participants and became increasingly intense until the end of the film, when the boy nearly hits the family maid with a real bullet. The volunteers’ subjective feelings closely tracked with their brain activity, implying a common neural experience of anxiety and dread, Naci says.
Next, after obtaining permission from their caregivers, the team put two brain-damaged patients into the scanner—a 20-year-old female patient who fell into a coma in 2007 after suffering brain damage of unknown origins, and the 35-year-old man. Despite having her eyes open throughout, the young woman showed no brain activity in response to the film, Naci says. In contrast, the man displayed peaks and valleys of brain activity that closely matched those of the healthy volunteers, suggesting that he might have been following the plot, the team reports online today in the Proceedings of the National Academy of Sciences.
The new study “opens the door to a whole new way” of searching for signs of awareness in people who have been misdiagnosed as being in a vegetative state, Naci says. Compared with following instructions or focusing on a contrived scenario, simply watching a film could provide an “effortless” way for patients who are unable to communicate to show that they are tuned into their surroundings, she says.
It’s too early to say whether the method will be useful for most apparently unaware and unresponsive brain injury patients, however, says Nicholas Schiff, a neurologist at Weill Cornell Medical College in New York City who wasn’t involved in the research. Although the technique was able to distinguish a high-functioning patient from one with much lower levels of brain activity, the vast majority of people with such injuries fall somewhere in between those two extremes, he says. In these patients, researchers are likely to see a highly variable mix of responses, and “it’s not clear” whether the TV clip technique will be able to detect consciousness in more ambiguous cases, he says.
Using film to trigger detectable signs of consciousness has another major limitation: Many brain-damaged patients can’t keep their eyes open and looking forward, or simply can’t see, says neurologist Andrew Goldfine of the Stony Brook Neurosciences Institute in New York, who wasn’t involved with the new study. Nor is it clear whether the similar patterns of brain activity between the healthy participants and the brain-damaged patient mean that the man is having the same “conscious” experience of the film, Naci notes.
Still, the study has provided some comfort to the patient’s family, she says. For many years after his injury, his father took him to see a film once a week, based on the conviction that he enjoyed it, she says. Eventually he stopped, but “we now do believe that this individual is enjoying being taken to the movies,” and that “we should provide more enriching environments” for such patients, she says.