Neural correlates of normal and impaired consciousness

Consciousness is notoriously difficult to conceptually define and measure, despite being central to human experience in both health and pathology. In recent years, the combined efforts of researchers working in the fields of philosophy, psychology and neuroscience have led to the development of a level-versus-contents bi-dimensional theoretical framework to assist the scientific study of consciousness. According to the bi-dimensional model of consciousness, conscious states are characterised by the general level of arousal (clinically tested as responsiveness) and the awareness of specific contents of consciousness (clinically tested as first-person reports of subjective experiences). This model allows clinical researchers to systematically explore the neural correlates of consciousness across a range of healthy and altered conscious states. In addition to physiological states, such as the different sleep stages, both chronic and transient pathologies of consciousness have been the subject of high-quality neurological research conducted over the last few years. Chronic pathologies of consciousness include coma, vegetative state, and minimally conscious state, whereas the different types of epileptic seizures are the most extensively investigated neurological conditions associated with transient alterations of consciousness. Multidisciplinary approaches to consciousness studies offer promising avenues to reach the dual goal of shedding some initial light on the so-far elusive neural correlates of consciousness and improving health-related quality of life in patients with chronic and transient neurological conditions affecting consciousness.