Tracking consciousness in minimal behavioural responsiveness

Consciousness is a complex construct with no universal definition. Especially in pathological conditions, it is less clear what is meant by (un)consciousness. How can one reliably observe and measure it? When it comes to bedside evaluation, this needs to be inferred via the evaluation of motor activity, with the aim to disentangle reflex from nonreflex behaviour. Despite systematic assessments, behavioural 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 the emerging neuro-ethical concerns stemming from the research of this challenging clinical population.