Neuroanatomical Basis of Consciousness
Neurology utilizes a localization based approach that has firmly established the functional neuroanatomy of consciousness. Clinical disorders can either impair the specific contents of consciousness, such as language or visual processing; or can interfere with the overall level of consciousness. The specialized brain networks controlling the level of consciousness are called the "consciousness system," and include cortical components, consisting mainly of bilateral frontoparietal association cortex, as well as subcortical components comprising multiple parallel arousal systems in the upper brainstem, thalamus, hypothalamus, and basal forebrain. Subcortical arousal systems include widespread projections acting through glutamate, gamma amino butyric acid, acetylcholine, epinephrine, dopamine, serotonin, histamine, and orexin. The bilateral higher order heteromodal association cortex acts together with the subcortical components of the consciousness system to control the level of alertness, attention, and awareness. Cortical anatomy is also crucial for other aspects of consciousness including hemispheric specialization, emotional drive, feature binding, top down, bottom up, task positive and task negative (default mode) attention systems, voluntary action, self awareness, and memory encoding for the report of conscious experience.