September 7, 2006

scientists react to ‘Brain activity in a vegative state’ paper to be published in Science

A group of collaborating UK and Belgian scientists have reported a study showing that a woman in a ‘vegetative state’ following severe head trauma can successfully understand spoken words.

Dr Narender Ramnani, Reader in Cognitive Neuroscience, Cognitive Neuroscience Laboratory, Department of Psychology, Royal Holloway University of London, said:

“These remarkable findings suggest that a patient in a vegetative state willfuly cooperated with scientists by following their instructions to systematically change the contents of their imagination. This adds weight to the view that she, and perhaps many other patients like her, might be quite capable of decision-making and have a rich and complex internal life. However, this finding is based on a single case so further research is needed to investigate this possibility more robustly. Future research might also make it possible for such patients to communicate their thoughts and intentions to others by controlling their own brain activity. Apart from the scientific points, the study also raises important ethical questions: given that such patients might be conscious and capable of making their own decisions, is it acceptable for others to terminate their lives without the consent of these patients?”

Paul Matthews, Professor of Clinical Neurosciences, Imperial College and MRC Clinical Research Professor, Department of Clinical Neurology, University of Oxford, said:

“When patients are in a vegative state they can react to stimuli but not in a truly meaningful way. Often patients will look as if they are interacting with the environment, which can be distressing for relatives, but this is simply a reaction to stimuli. In a vegative state there can be many signs of types of brain function, but there is no evidence for conscious interaction.

“A vegative state is different to a coma. When a patient is said to be in a coma they remain unreactive to stimuli for long periods of time. If this irreversible it may lead to the decision to turn off a life support machine (a decision which wouldn’t be taken for patients in a vegative state). The key criteria for irreversible coma is a test that demonstrates there is no significant brain function.

“The paper explained that in the case of this patient there was no evidence of meaningful interaction with the environment. In my opinion The fMRI study alone does not provide sufficient evidence that there is conscious interaction with the environment.

“The conclusions suggest that consciousness can be reduced to activity in individual functional systems in the brain, rather than that it is a consequence of an integrated self-recognition of their state. If individual brain systems function (e.g. word recognition or a patterned response to a command) was the only requirement for consciousness, then the computer on which I am typing would be conscious – a highly unattractive conclusion.

“This paper again confirms the potential for fMRI to extend information available from conventional electrophysiological testing in clinical evaluations. It has long been recognised that specific brain functions can be preserved in patients in a vegetative state and the electrophysiological evidence for preserved evoked potentials and TMS responses are consistent with this for visual and motor systems.

“Contrary to the claim of the authors, however, the observations to not establish either that the patient made a “decision to cooperate” or that she had self-awareness. Response to stimuli, even complex linguistic stimuli, does not provide evidence of a “decision” to respond (e.g., withdrawal from an unexpected painful pin prick does not represent a “decision” to respond!). The authors did not image activity related to “decision” (a challenge largely unmet yet in the literature), merely the responses to command stimuli. While these are more complex stimuli than vision or sound, it is a matter of everyday experience that we respond to complex stimuli without explicit conscious decision (e.g., the differing responses to the call of “fare?” vs. “fire!” on a crowded bus).”