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Neurol Sci (2015) 36:505513 DOI 10.1007/s10072-015-2072-x
REVIEW ARTICLE
Neural correlates of consciousness: what we know and what we have to learn!
Rocco Salvatore Calabr Alberto Cacciola
Placido Bramanti Demetrio Milardi
Received: 27 October 2014 / Accepted: 9 January 2015 / Published online: 15 January 2015 Springer-Verlag Italia 2015
Abstract Consciousness is a multifaceted concept with two major components: awareness of environment and of self (i.e., the content of consciousness) and wakefulness(i.e., the level of consciousness). Medically speaking, consciousness is the state of the patients awareness of self and environment and his responsiveness to external stimulation and inner need. A basic understanding of consciousness and its neural correlates is of major importance for all clinicians, especially those involved with patients suffering from altered states of consciousness. To this end, in this review it is shown that consciousness is dependent on the brainstem and thalamus for arousal; that basic cognition is supported by recurrent electrical activity between the cortex and the thalamus at gamma band frequencies; and that some kind of working memory must, at least eetingly, be present for awareness to occur. New advances in neuroimaging studies are also presented in order to better understand and demonstrate the neuro-physiological basis of consciousness. In particular, recent functional magnetic resonance imaging studies have offered the possibility to measure directly and non-invasively normal and severely brain damaged subjects brain activity, whilst diffusion tensor imaging studies have allowed evaluating white matter integrity in normal subjects and patients with disorder of consciousness.
Keywords Consciousness Disorders of consciousness
Ascending reticular activating system Default mode
network Neuroimaging
Introduction
Consciousness is a multifaceted concept with two major components: awareness of environment and of self (i.e., the content of consciousness) and wakefulness (i.e., the level of consciousness).
Whereas the level of arousal reects the overall state of activity in the brain, conscious awareness is a more dynamic and complex process involving various cerebral networks at any one time. There are several contrasting theories on how we become aware of environmental and internal stimuli, although it is widely believed to depend on interactions between the cortex and specic and non-specic (i.e., intralaminar) thalamic nuclei [1, 2].
Conscious awareness and arousal states also interact. Without arousal, there is no awareness, and in states of high arousal, awareness...