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Sean Tanabe

2 papers in the library · 51 citations · publishing 2021-2024

Papers

Higher-order sensorimotor circuit of the brain's global network supports human consciousness.

NeuroImage May 1, 2021 Pengmin Qin, Xuehai Wu, Changwei Wu et al. 51 citations

Consciousness depends on a network of brain regions that integrate sensory and motor information. Analyzing fMRI data from people in preserved (awake, fully conscious brain-injury survivors), reduced (N1-sleep, minimally conscious), and lost (N3-sleep, anesthesia, unresponsive wakefulness) states, plus a unique rapid-eye-movement (REM) sleep group, researchers identified key hubs whose degree centrality—a measure of network importance—dropped significantly when consciousness was reduced or absent. These hubs included the supplementary motor area, bilateral supramarginal gyrus, supragenual/dorsal anterior cingulate cortex, and left middle temporal gyrus. A higher-order sensorimotor circuit connecting these regions showed functional connectivity that correlated with consciousness levels across groups and remained active in REM sleep, suggesting this circuit supports consciousness and offers new targets for treating disorders of consciousness.

Evaluation of putative signatures of consciousness using specific definitions of responsiveness, connectedness, and consciousness.

British journal of anaesthesia February 1, 2024 Cameron P Casey, Sean Tanabe, Zahra Z Farahbakhsh et al.

Many EEG-based measures previously thought to indicate unconsciousness actually track sensory connectedness—awareness of the environment—rather than consciousness itself. Analyzing data from the UNderstanding Consciousness Connectedness and Intra-Operative Unresponsiveness Study, researchers tested 10 resting-state EEG markers derived from unresponsive subjects during dexmedetomidine and propofol sedation and natural sleep. While several markers correlated with reported subjective experience (consciousness), none were specific to consciousness alone; each was also linked to connectedness. Loss of normalized-symbolic transfer entropy (front to back) was associated with connectedness across all conditions, and the shift from disconnected consciousness to unconsciousness involved significant decreases in permutation entropy and spectral exponent. The findings caution against equating unresponsiveness with unconsciousness.