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Hearing and Donuts (Brain and Bagels) Seminar
November 4, 2022 @ 8:30 am - 9:30 am
Matt Banks, Ph.D.
Professor of Anesthesiology, UW-Madison
Topic: Altered functional geometry of human cortical networks during states of reduced consciousness
Although sleep and anesthesia are predicted to share common neural signatures of transitions into and out unconsciousness, supportive evidence has been elusive. We identified these signatures using intracranial electroencephalographical recordings in neurosurgical patients. We applied diffusion map embedding map cortical location into a space where proximity indicates functional similarity using a normalized connectivity (‘diffusion’) matrix, itself a rich source of information about network properties. During reduced consciousness, diffusion matrices exhibited decreased effective dimensionality, reflecting reduced network entropy. Furthermore, functional brain regions exhibited tighter clustering in embedding space with greater distances between regions, corresponding to decreased differentiation and functional integration. These changes were not region-specific, suggesting global network reorganization. These results strongly suggest common neural substrates for loss and recovery of consciousness during anesthesia and sleep, providing a systems-level mechanistic understanding within an intuitive geometric context and laying the foundation for evaluation of cortical state transitions in clinical settings.