Brain Imaging as a Diagnostic and as a Communicative Tool in Disorders of Consciousness

Recently, a number of neuroimaging studies have been conducted, aimed at detecting signs of consciousness in patients with a diagnosis of vegetative or minimally conscious state. The contributions appeared during an ongoing international ethical and socio-legal debate, on the admissibility of decisions to withdraw artificial nutrition from vegetative patients, thereby allowing them to die. We argue that neuroimaging is more likely to contribute to medical diagnosis and decision making if two requirements are met. First, those studies inferred awareness from the neural correlates of cognitive processes that are assumed to involve consciousness. However, neural correlates of consciousness proper, as defined by current philosophy and neuroscience, are the only admissible non-behavioral signs of awareness. Second, in those studies patients attempted to answer medically irrelevant questions by modulating their cortical activity in imagery tasks. We suggest patients should instead be queried on matters relevant to their clinical condition and quality of life.