Dr. Daniela J. Lamas at The New York Times:

A provocative large study published last year in The New England Journal of Medicine suggests that at least one in four people who appear unresponsive actually are conscious enough to understand language. As a doctor who sometimes sees patients like this, these findings are, in a word, terrifying.

Studies like this raise the possibility that there are tens of thousands of men and women locked inside their own minds, isolated to a degree I cannot even imagine. They are voiceless and largely invisible, with some of them being cared for in nursing facilities.