Consciousness and Its Disorders

Everybody knows what consciousness is and yet a universally accepted definition is lacking. While the scientific problem of consciousness has been denied for the most part of the 20th century, the current consensus is that there is indeed a problem to be solved. And while philosophy has dealt with consciousness for centuries, the current consensus is that there is a problem that might not be solvable. We briefly review the landscape of philosophical positions on consciousness, deliberately avoiding the ubiquitous distinction between the “hard” and “easy” problems. Instead, we focus on the neuroscientific problems of consciousness. Our main purpose is to review how the field advanced on these problems, from the early quest for the neural correlates of consciousness to the development of several theoretical models of consciousness, and some of the current controversies that are setting up new directions of research. This chapter closes with a discussion on the clinical relevance of consciousness research, in the context of diagnosing and treating patients suffering from post-comatose disorders of consciousness.