consciousness
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Physiology
- state of awareness of self & suroundings
- largely dependent upon activity in the cerebral cortex
- the adrenergic (locus ceruleus) & cholinergic (pedunculopontine) systems may play a role
- thalamocortical circuits may play a role in consciousness[3]
- specific thalamic nuclei establish direct, targeted connections to defined cortical areas, relaying sensory signals with high precision
- nonspecific nuclei, by contrast, project widely across multiple cortical areas, playing a role in regulating general cortical arousal & supporting complex cognitive functions
- the thalamus has two distinct cell classes, core cells & matrix cells
- core cells primarily innervate granular layers of the cerebral cortex
- matrix cells diffusely innervate the supragranular cerebral cortex
- specific thalamic nuclei are generally core-rich
- nonspecific nuclei are generally matrix-rich
- however each nucleus contains a mixture of core cells & matric cells
- interactions between matrix-rich nonspecific thalamus & thick-tufted cortical layer-5 pyramidal neurons may play a role in consciousness
- supragranular distal apical dendrites of layer-5 pyramidal neurons play a role in corticocortical feedback processing
- infragranular proximal somatic dendrites play a role in corticocortical feedforward processing
- matrix-rich nonspecific thalamus targets oblique dendrites along the apical trunk of the layer-5 pyramidal neurons, modulating the dendrosomatic coupling between supragranular distal apical dendrites & infragranular proximal somatic dendrites
- coupling between these dendritic compartments of the layer-5 pyramidal neurons may enable large-scale cortical integration
- disruption of this coupling by suppression of nonspecific thalamocortical connectivity may contribute loss of consciousness induced by general anesthesia[3]
* mean arterial blood pressure of >= 50 mm Hg may be needed to maintain consciousness[2]
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References
- ↑ Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
- ↑ Jump up to: 2.0 2.1 Peberdy MA et al. Cardiopulmonary resuscitation in adults and children with mechanical circulatory support: A Scientific Statement from the American Heart Association. Circulation 2017 Jun 13; 135:e1115 PMID: https://www.ncbi.nlm.nih.gov/pubmed/28533303
- ↑ Jump up to: 3.0 3.1 3.2 Huang Z, Mashour GA, Hudetz AG. Propofol disrupts the functional core-matrix architecture of the thalamus in humans. Nat Commun. 2024 Sep 9;15(1):7496. doi:http://dx.doi.org/ 10.1038/s41467-024-51837-1. PMID: https://www.ncbi.nlm.nih.gov/pubmed/39251579