Thalamus modulates consciousness via layer-specific control of cortex

Neurons in the thalamus and deep cortical layers are most sensitive to changes in consciousness level, consistent across different anesthetic agents and sleep. Deep layer activity is sustained by interactions with the central lateral thalamus. Consciousness also depends on deep layer neurons providing feedback to superficial layers, suggesting long-range feedback and intracolumnar signaling are important. Stimulating the central lateral thalamus in anesthetized macaques effectively restored arousal and wake-like neural processing in a location- and frequency-specific manner. These findings suggest layer-specific thalamocortical correlates of consciousness and inform how targeted deep brain stimulation can alleviate disorders of consciousness.

Study at a glance

Abstract

SUMMARY: Functional MRI and electrophysiology studies suggest consciousness depends on large-scale thalamocortical and corticocortical interactions. However, it is unclear how neurons in different cortical layers and circuits contribute. We simultaneously recorded from central lateral thalamus (CL) and across layers of frontoparietal cortex in awake, sleeping and anesthetized macaques. We found that neurons in thalamus and deep cortical layers are most sensitive to changes in consciousness level, consistent across different anesthetic agents and sleep. Deep layer activity is sustained by interactions with CL. Consciousness also depends on deep layer neurons providing feedback to superficial layers (not to deep layers), suggesting long-range feedback is important, as well as intracolumnar signaling. To show causality, we stimulated CL in anesthetized macaques and effectively restored arousal and wake-like neural processing. This effect was location- and frequency-specific. Our findings suggest layer-specific thalamocortical correlates of consciousness and inform how targeted deep brain stimulation can alleviate disorders of consciousness.