NeuroImage
May 1, 2020
Matthew I Banks, Bryan M Krause, Christopher M Endemann et al.
78 citations
Disruption of cortical connectivity likely contributes to loss of consciousness during sleep and general anesthesia, but the degree of overlap in mechanisms is unclear. Using intracranial recordings from five adult neurosurgical patients, alpha-band connectivity (measured by weighted phase lag index) was compared across natural sleep stages and propofol anesthesia. In wake states, alpha-band connectivity within the temporal lobe was dominant, a pattern largely unchanged in light sleep (N1, REM) and sedated states. Transitions into states of reduced consciousness (deep sleep N2/N3 and anesthesia-induced unresponsiveness) showed dramatic shifts, with dominant connections moving to prefrontal cortex. The findings suggest common mechanisms of loss of consciousness in sleep and anesthesia.
Cerebral cortex (New York, N.Y. : 1991)
August 23, 2023
Bryan M Krause, Declan I Campbell, Christopher K Kovach et al.
Theories of consciousness propose that brain mechanisms for losing and regaining consciousness are similar regardless of cause. Using intracranial electroencephalography in neurosurgical patients during propofol anesthesia and overnight sleep, researchers found strikingly similar reorganization of cortical networks. Effective dimensionality of functional connectivity decreased during reduced consciousness (anesthesia unresponsiveness, N2 and N3 sleep), indicating lower network complexity. These changes were global, not region-specific. Brain regions became more functionally distant yet individual recording sites closer to nearest neighbors, reflecting decreased differentiation and integration. This network reorganization constitutes a common neural signature of reduced consciousness across anesthesia and sleep, providing a framework for understanding neural correlates of consciousness.
eNeuro
January 1, 2017
Andrew M Haun, Masafumi Oizumi, Christopher K Kovach et al.
A pattern of integrated information—a measure inspired by integrated information theory—corresponds to what a person consciously sees, whereas broader information measures such as mutual information and entropy do not. Intracranial recordings from six neurosurgical patients showed that, in object-sensitive brain areas, the hierarchical causal structure of neural interactions matched the subjects' conscious percepts when they viewed faces or objects under conditions that dissociate perception from the physical stimulus (continuous flash suppression and backward masking). Unsupervised classification confirmed that integrated information patterns, but not other information measures, clustered according to the subjects' visual experiences. The findings suggest that locally integrated information plays a key role in the neural basis of conscious object perception.