The Current of Consciousness: Neural Correlates and Clinical Aspects.

Consciousness is understood through its neuroanatomic basis, with recent studies identifying EEG, ERP, and fMRI signals that predict aspects of conscious experience. Disorders affecting the reticular activating system alter the level of consciousness, while cortical disorders such as seizures, migraines, strokes, and dementia disrupt phenomenal consciousness. The memory theory of consciousness offers a new explanation of phenomenal consciousness that may better account for experimental studies and clinical experience. Despite advances in understanding the physiology underlying both level and phenomenal consciousness, the complete neurobiological basis remains unknown.

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Abstract

PURPOSE OF REVIEW: In this review, we summarize the current understanding of consciousness including its neuroanatomic basis. We discuss major theories of consciousness, physical exam-based and electroencephalographic metrics used to stratify levels of consciousness, and tools used to shed light on the neural correlates of the conscious experience. Lastly, we review an expanded category of 'disorders of consciousness,' which includes disorders that impact either the level or experience of consciousness. RECENT FINDINGS: Recent studies have revealed many of the requisite EEG, ERP, and fMRI signals to predict aspects of the conscious experience. Neurological disorders that disrupt the reticular activating system can affect the level of consciousness, whereas cortical disorders from seizures and migraines to strokes and dementia may disrupt phenomenal consciousness. The recently introduced memory theory of consciousness provides a new explanation of phenomenal consciousness that may explain better than prior theories both experimental studies and the neurologist's clinical experience. Although the complete neurobiological basis of consciousness remains a mystery, recent advances have improved our understanding of the physiology underlying level of consciousness and phenomenal consciousness.