The interrelationship between the level and the content of consciousness in different pathophysiologic and pharmacologic states. Contemporary advances in neuroscience have unmasked a wide knowledge gap in the neurophysiologic characterization of human consciousness. The level of consciousness is generally assessed by either wakefulness or responsiveness to external stimuli. The content of consciousness includes internal (self) and external (environmental) awareness. The content of consciousness is difficult to assess in unresponsive and noncommunicative patients (e.g., coma or general anesthesia settings). The temporal pattern of recovery in neuronal networks that mediate the content of consciousness in the severely injured human brain has not been completely elucidated. Adapted from Laureys  with permission of the publisher Elsevier Ltd.