Tetsuo Furukawa, professor emeritus of neurology at Tokyo Medical and Dental School, is a rarity in Japan: a neurologist who has been crusading against the practice of transplanting organs from brain-dead donors. Furukawa worries that patients in a supposedly brain-dead state may nevertheless feel pain, or some lesser sensation, when the surgeon's knife cuts into their bodies to procure organs.

This may come as a surprise to Japanese, for whom the notion of brain-death has become so common as to be rendered uncontroversial.

But "it has not been scientifically proven that brain-dead people are completely unconscious when they are classified as brain-dead," Furukawa says. "It is possible that they cannot express what they feel in a way that can be detected by others through modern technology."