Patients in a vegetative state are supposed to be completely unaware of their surroudings. Whether this is true is important for negotiating round the complicated legal and ethical tangles that surround the care of such patients. Now, scientists have used brain imaging technology to show that at least one patient is indeed aware of her surroundings and can respond to instructions.
A woman is playing a game of tennis. As she swats the ball around, she is being watched by a stranger. We might automatically read something sinister into this scene but there is a catch. This game isn’t real – it’s taking place entirely in the woman’s mind. The woman herself lies in a hospital bed, where she has stayed for the past year in what doctors call a ‘vegetative state’. The stranger is no voyeur – he is a neuroscientist, watching the woman’s brain on a monitor, and what he is seeing could shake the medical world.
Few medical conditions pose more difficult ethical dilemmas than the vegetative state. Cases like Terri Schiavo’s, where relatives have to make the unenviable decision to cut off support, can attract international notoriety, even drawing stances from the Vatican and the White House (right: protesters at the Schiavo case, killbyte@flickr).
The problem with the vegetative state is that we know precious little about it. It is defined as a state of wakefulness with no awareness, differing from a coma in that patients go through sleep-wake cycles like the rest of us. They may even open their eyes or smile, but it won’t be in response to a friendly face or a good jokes. Their responses are neither purposeful nor consistent, and this is a key element for diagnosing the condition.
After a month, the patient is said to be in a persistent vegetative state, and if the condition does not improve within 3-12 months, the state is said to be permanent. The key questions are these: are these people really incapable of responding to the world around them, and will they ever truly ‘wake up’? The debate has been fuelled by people like Terry Wallis, who spent 19 years in a vegetative state before waking up and rejoining his family. If cases like Terry exist, how can we be sure that other patients will never recover?
Communicating through thought
To get some answers, Adrian Owen at the MRC Cognition and Brain Sciences Unit, Cambridge, has been using brain scanning techniques to visualise the thoughts of people in vegetative states. Most recently, his team has been working with a 23-year old woman who was left with severe brain injuried following a car accident in July 2005. Since then, a team of different medical specialists concluded that she fulfilled all the diagnostic criteria for being in a vegetative state.
Owen begs to differ. He used a brain-scanning technique called functional magnetic resonance imaging – fMRI – to look at how the woman’s brain responded to simple stimuli. At first, he played simple sentences to her, as well as garbled nonsense that sounded very similar. The spoken words alone caused neurons to fire in the woman’s superior and middle temporal gyri, regions of the brain involved in processing speech and language. And if the sentences contained ambiguous words, even more speech-related regions were brought into play.
While these findings provided tantalising hints of purposeful brain activity, they were far from conclusive. For their next test, Owen’s team asked the woman to imagine playing a game of tennis, and as predicted, the neurons in her motor area lit up. When they asked her to imagine more precise activities, such as walking through the rooms of her house, her brain became a hive of activity. The motor cortex was again brought into play, but this time, the team also saw activity in the parahippocampal gyrus (responsible for retrieving geographical memories) and the posterior parietal cortex (responsible for mapping object locations). And amazingly, her responses in all the tests all the tests were completely indistinguishable from those of healthy volunteers.
“These are startling results,” says Owen. “The patient retained the ability to understand spoken commands and to respond to them through her brain activity, rather than through speech or movement Her decision to work with us by imagining particular tasks when asked represents a clear act of intent which confirmed beyond any doubt that she was consciously aware of herself and her surroundings.” This was no vegetative state.
These results clearly raise some massive ethical questions over the fates of other patients currently in vegetative states. But it would be vastly imprudent to make generalities based a single case, and it is unlikely that all such people are secretly aware of their surroundings. Nor is awareness the only possible explanation for the woman’s responses, and some scientists remain unconvinced. Nonetheless, the study provides compelling evidence that at least some vegetative state patients do indeed show awareness, and with fMRI, we can find them.
Whether responsive brain activity means that the woman in Owen’s study will eventually join the ranks of Terry Wallis is uncertain. But identifying such patients may prompt increased care and attention from loved ones and hospital staff, perhaps with positive results. In the mean time, more research, improving imaging techniques and a growing understanding of the brain could allow these patients to communicate with their loved ones through their thoughts.