Propofol disrupts the functional core-matrix architecture of the thalamus in humans

Anesthesia-induced unconsciousness involves a shift in the functional geometry of thalamocortical circuits, moving from a normal unimodal-transmodal pattern to a transmodal-deficient one. This alteration is linked to spatial variations in matrix cell composition within the thalamus, suggesting that disrupted connectivity of matrix cells plays a key role in the loss of consciousness. The study used functional magnetic resonance imaging in healthy volunteers during conscious baseline, deep sedation, and recovery, applying a functional gradient mapping technique to delineate these changes. The findings bridge cellular and systems-level understanding of consciousness.

Study at a glance

Abstract

Research into the role of thalamocortical circuits in anesthesia-induced unconsciousness is difficult due to anatomical and functional complexity. Prior neuroimaging studies have examined either the thalamus as a whole or focused on specific subregions, overlooking the distinct neuronal subtypes like core and matrix cells. We conducted a study of heathy volunteers and functional magnetic resonance imaging during conscious baseline, deep sedation, and recovery. We advanced the functional gradient mapping technique to delineate the functional geometry of thalamocortical circuits, within a framework of the unimodal-transmodal functional axis of the cortex. Here we show a significant shift in this geometry during deep sedation, marked by a transmodal-deficient geometry. This alteration is closely linked to the spatial variations in the matrix cell composition within the thalamus. This research bridges cellular and systems-level understanding, highlighting the crucial role of thalamic core–matrix functional architecture in understanding the neural mechanisms of states of consciousness. Anesthesia alters thalamocortical circuits, causing a shift from unimodal-transmodal functional geometry to a transmodal-deficient pattern. This change is associated with disrupted matrix cell connectivity, suggesting a mechanism for unconsciousness.