In The New Yorker, Jerome Groopman discusses the work of Adrian Owen, a researcher at Cambridge University's Cognitive and Brain Sciences Unit who has been using functional imaging to assess patients in a vegetative state.
Neurologists face major problems in diagnosing the persistent vegetative state (PVS) and other "disorders of consciousness" such as the minimally conscious state (MCS), not least because there is no reliable means of assessing the level of consciousness in patients.
Large proportions of patients in such conditions are therefore misdiagnosed, and, until recently, most doctors assumed not only that such patients were incapable of higher cognitive functions, but also that there is no possibility of recovery. However, in the past year or so, there have been several cases of vast improvements in the brain function of patients with disorders of consciousness.
Earlier this year, for example, researchers from Weill Cornell Medical College in New York used deep brain stimulation to increase arousal levels and motor control in a patient who had been in a minimally conscious state for more than 6 years.
And one of Owen's own studies, published in Science about a year ago, showed that a woman in her early 20s who had been in a vegetative state for 5 months after sustaing severe traumatic brain injury in a car accident was able to imagine playing tennis and to comprehend various spoken sentences, leaving no doubt that she was consciouosly aware of herself and of her surroundings.
This latter study, as well as Owen's earlier work, and that of researchers at the J.F.K. Johnson Rehabilitation Institute in Edison, New Jersey (who were involved in the other study mentioned above) are discussed in detail in the New Yorker article. Groopman also discusses the ethical issues raised by the care of patients with consciousness disorders, and current medical thinking about these disorders.
Reference:
Owen, A. M. et al. (2006). Detecting awareness in the vegetative state. Science 313: 1402. [PDF]
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I doubt Owen "showed that" the woman was able to imagine playing tennis. We already knew, prior to this study, that there are all kinds of neural responses in PVS: P300 responses, for instance. We didn't know whether these responses were automatic or reflections of consciousness. We still don't after this study. Owen's evidence is consistent with either hypothesis. I expect, though, that we will know soon - a study that rules out automatic processing isn't hard to imagine.
What is special, and as Steven Laureys says a clinical challenge, is to determine the blur boundarie between minimally concious state and vegetative state: the clinical "grey zone" distinghising MSM (minimally concious state and VS (vegetative state); with mayor consequences in the ethical and legal dimension regarding disorders of conciousness and the withdrawal of life-prolonging treatments adn the determination of "brain" death or simply death.
Being wakeful but unawareness seems to be slowly shifting due to research like that performed by A. Owen and his group, in which some residual activity appears to be present in motor cortices and hipocampi, during an imaginary task (imagine playing tennis or walking trhough a room), revealing the intact workings of some mechanisms of intention, and therefore human conciousness. But we have to be cautious we don´t know exactly what are the neural components of human conciousness yet.