Responsiveness in DoC: A quest for consciousness?

Abstract

Interest on consciousness is growing, but how it arises in the brain remains fundamentally unsolved. The variety of brain mechanisms, the impairment of which is observed in DoC, has implication in neuroscience, in suggesting that consciousness results of a complex functional arrangement interacting with but distinct from other higher brain processes. Neuroimaging has challenged the current criteria for consciousness and responsiveness by documenting residual high-level aspects of brain activity in DoC. The clinical standards to classify patients as conscious or unconscious are questioned, and neurologists are confronted with unresolved issues about diagnosis, pain, and predictability of recovery. The epistemological issue remains the defi nition of consciousness beyond subjective feeling, verbal report, probabilistic inference, and pragmatic principles. Classifi cation rests on responsiveness in the absence of a theory about consciousness inclusive of its quantitative characterization. Proper defi nitions for and an up-to-date scrutiny of the available descriptors are needed to think scientifi cally about consciousness.