Measuring (un)conscious states: research, clinical applications & ethics

Consciousness is a multidimensional construct with no widely accepted definition. Especially in pathological conditions it is less clear what exactly is meant by unconsciousness, how it can be reliably observed or measured. When it comes to bedside detection of consciousness, this needs to be inferred via the evaluation of motor activity, with the aim to disentangle reflex from nonreflex behavior. Despite systematic assessments, behavioral evaluation is not straightforward due to patients’ physical and cognitive condition. As a result, the presence of consciousness can be underestimated. During the last two decades, the diagnosis of disorders of consciousness has been notably facilitated by means of technological modalities. Although most of such research has concerned patient groups, lately single-patient differentiation by means of automatic algorithms has been achieved. Here, I will show how functional neuroimaging has assisted patient diagnosis, how it can be potentially informative of clinical outcome and what these findings teach us about typical conscious states. As this type of research touches upon philosophical and ethical issues, I will discuss show the emerging neuro-ethical concerns stemming from the research of this challenging clinical population.