Thus, conscious access is achieved by corticocortical loops and corticosubcortical loops ( 10). Deep brain nuclei such as the thalamus and cerebellar nuclei have been identified as key structures for the persistent representation of information (or reverberation) within the cortex ( 8, 9). Explicit neural network–based simulation of the GNW incorporates both thalamic and cortical neurons ( 4, 6, 7). According to the global neuronal workspace (GNW) theory, awareness occurs when a specific piece of information is made available to a broad cortical network interconnected through long-distance corticocortical axons ( 3, 4) under the coordination of nuclei of the brainstem ascending reticular formation and the projecting thalamocortical neurons ( 5). The thalamocortical loops and sensorimotor couplings (TCL) theory stipulates that consciousness is “determined by synchronous activity in the thalamocortical system” ( 2).
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Several theories have been proposed for the cerebral mechanisms of consciousness ( 1). Thus, DBS restored the two dimensions of consciousness, arousal and conscious access, following consciousness loss, paving the way to its therapeutical translation in patients with disorders of consciousness.Ĭonsciousness can be studied at two different levels: arousal, emerging from brainstem ascending reticular systems and basal forebrain, and awareness, mainly characterized by the conscious access to a specific piece of information. Last, DBS restored a broad hierarchical response to auditory violations that was disrupted under anesthesia. None of these effects were obtained during the stimulation of a control site in the ventrolateral thalamus. Moreover, DBS restored a broad dynamic repertoire of spontaneous resting-state activity, previously described as a signature of consciousness.
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During anesthesia, central thalamic stimulation induced arousal in an on-off manner and increased functional magnetic resonance imaging activity in prefrontal, parietal, and cingulate cortices. We applied anesthesia to suppress consciousness in nonhuman primates. We tested the hypothesis that deep brain stimulation (DBS) of central thalamus might restore both arousal and awareness following consciousness loss. Loss of consciousness is associated with the disruption of long-range thalamocortical and corticocortical brain communication.