Disorders of consciousness, as conceived today, are a relatively recent phenomenon. Indeed, until about 60 years ago, individuals who suffered from a brain injury of the severity that typically leads to a disorder of consciousness rarely survived. In the fifties, the introduction of mechanical ventilation radically changed our ability to extend the life of these patients. This revolutionary advance in critical care, however, confronted clinicians with an almost unprecedented, and highly perplexing, neurological condition in which patients are alive but not responsive to their surroundings. In the past 30 years, and particularly since the introduction of noninvasive brain imaging techniques, patients suffering from this neurological condition have been at the center of flourishing clinical research, aimed at developing a full understanding of loss and recovery of cognitive function after severe brain injury, and scientific interest, aimed at understanding one of the most central aspects of the human brain: consciousness.