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consciousness

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]

Related

loss of consciousness (LOC) subconsciousness

Specific

altered state of consciousness awareness

General

physiologic process

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
  2. 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: 28533303
  3. 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: 10.1038/s41467-024-51837-1. PMID: 39251579