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Can We "Talk" to Vegetative Patients Via fMRI?
Neuroscientists claim to have communicated with a patient who appears to be in a vegetative state by asking him questions and studying fMRI images of his brain directly afterward.
The Claim
Asking a persistently vegetative patient a question while his head is in a brain-scan machine, doctors can interpret his answer from the results of the scan. This would be the first time a patient with lack of consciousness would be able to give doctors feedback on his care and pain levels. The question-and-answer technique first appeared to have success in 2010.
The Study
A person is in a vegetative state (VS) when he is "awake" but not aware, as opposed to being in a coma, in which the patient is asleep and not aware. In VS, he can open his eyelids, swallow food, and demonstrate sleep cycles. His body may respond to external stimuli or vocalize, but apparently without self-awareness or awareness of his surroundings.
In the United States, the condition is called a persistent vegetative state (PVS) after a month without recovery of consciousness. After a year, it is called permanent, which reflects the slim likelihood that consciousness will return after this point, according to a study in the New England Journal of Medicine. Naming and defining these stages vary by country and are still disputed.
The patient in question is 39-year-old Scott Routley, who has been in PVS for 12 years following brain trauma suffered in a car accident. Professor Adrian Owen of the Brain and Mind Institute at the University of Western Ontario (@comadork on Twitter, fittingly), says that Routley answered questions about his pain level by "thinking" them and allowing Owen's team to see his answers via fMRI.
Images of the brain seen through fMRI are often used to identify areas of the brain associated with specific activities before brain surgery, to judge the level of risk. These images show blood flow to brain tissues. Deoxygenated blood is much more magnetized than oxygenated blood, and fMRIs can see the difference (granted, there is a lot of noise in the signal, and the results can be messy and hard to interpret). When neurons in the brain are activated, freshly oxygenated blood rushes to the site, visible as a demagnetized zone in the brain about 5 seconds after the nerve fires. That's how fMRI scanners create a picture of brain activation.
Owen's technique begins with establishing a baseline of the person's brain activity, then asking the patient to visualize doing a series of routine activities, such as playing a sport or walking a familiar path. The team takes note of what areas of the brain activate when the patient imagines these activities. Then the doctors ask the patient yes-or-no questions, asking the patient to visualize one specific image for yes and another for no. The idea is that if "walking down a path" means no, and the scientists see the fMRI signature for "walking down a path" after they ask the question, they'll know the patient is trying to say no.
Routley's doctors asked him if he was in pain, and the image for "no" came up. Owen alleges that his method is reliable enough to assert that Routley is not in pain. Owen has claimed that 20 percent of PVS patients could be capable of communicating using his system.
The Backstory
Owen has been pushing this idea since 2006, when he first published his fMRI findings in Science, saying with one patient he had "confirmed beyond any doubt that she was consciously aware of herself and her surroundings." That short article spawned a number of doubtful responses, like that of neurologist Daniel Greenberg, who believed the idea was promising but the study design had flaws, saying that "words and sentences can induce activation in people who are clearly unconscious."
A big part of the problem is the slippery nature of terms like conscious and aware. Owen claims patients like Routley are conscious, but many other experts disagree. Routley still conforms to a clinical diagnosis of PVS, and many experts hold to the notion that it is fundamentally impossible to communicate with patients in a vegetative state.
One explanation is that Routley is not truly in a vegetative state. Last November the prestigious Coma Science Group in Belgium called for new guidelines for diagnosing and classifying these disorders of consciousness, using evidence from Owen as well as from other researchers. They brought together neuroimaging studies that have "demonstrated that a small subset of unresponsive 'vegetative' patients might show unambiguous signs of consciousness and command following inaccessible to bedside clinical examination." That is, an external assessment of the patient might reveal no signs of consciousness, but brain imaging techniques like Owen's could. The Coma Science Group suggested a new diagnosis code and medical subject heading in the US National Library of Medicine for "minimally conscious state" (MCS). Currently, MCS is still listed in the same entry with PVS, and the clinical distinction is controversial.
Michael Miller of the department of psychological and brain sciences at the Sage Center for the Study of the Mind at UC Santa Barbara has published extensively about the reliability, or lack thereof, of fMRIs. (His most famous study found functional activity in the brain of a dead salmon.) In an email, the fMRI skeptic reiterated the likelihood of false positives with fMRI when the researcher isn't careful, but adds, "Having said that, Adrian Owen is an extremely careful and thoughtful fMRI researcher, and his work on vegetative and minimally-conscious patients is meticulous and truly groundbreaking."
Owen says one of the next steps is to use an electroencephalogram, which is cheaper and directly measures electrical activity in the brain, though it is less precise than fMRI.
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