Three-node network motifs—recurring patterns of connections—reorganize in the brain during anesthetic-induced unconsciousness and recovery. In nine healthy volunteers undergoing a 3-hour anesthesia protocol, electroencephalography (EEG) recordings in the alpha band (8–13 Hz) showed that two specific motifs (motifs 1 and 5) changed their topology significantly between responsive and unresponsive states. Motif 1 consisted of long-range chain-like connections, while motif 5 comprised short-range loop-like connections. The topological reorganization of motif 5 preceded the return of responsiveness, and motif 1 accompanied it, suggesting these motifs may help reveal neural correlates of consciousness.
Amplitude-based (AEC) and phase-based (wPLI) measures of functional connectivity yield different patterns of brain network activity across states of consciousness. In nine healthy participants undergoing propofol and isoflurane anesthesia, AEC showed strongest connectivity during deep unconsciousness, while wPLI showed strongest connectivity during full consciousness. AEC outperformed wPLI in classifying anesthetic-induced unconsciousness from baseline (83.7% accuracy), distinguishing deep from light unconsciousness (66.3% vs. 56.2%), and separating responsiveness from unresponsiveness (76.0% vs. 63.6%). Combining both measures did not improve accuracy over AEC alone. The authors conclude that envelope-based measures better detect alterations in brain connectivity across levels of anesthetic-induced unconsciousness.