Thousands of brain-damaged people who are treated as if they are almost completely unaware may in fact hear and register what is going on around them but be unable to respond, a new brain-imaging study suggests. The findings, if repeated in follow-up experiments, could have sweeping implications for how to care best for these patients. Some experts said the study, which appeared yesterday in the journal Neurology, could also have consequences for legal cases in which parties dispute the mental state of an unresponsive patient. The research showed that the brain-imaging technology, magnetic resonance imaging, can be a powerful tool...