Circuit-level dynamics and propagation of slow wave activity modulate their interplay during the awakening process.
iScience December 19, 2025 Antonio Pazienti, Mariel Müller, Conrado A Bosman et al.
Slow-wave activity (SWA) in non-REM sleep and anesthesia is a hallmark of unconsciousness, but how it changes during the return to consciousness is unclear. Recording multi-area and laminar activity in mouse posterior parietal (PPC) and primary visual (V1) cortices during spontaneous awakening from isoflurane anesthesia, the authors show that spectral power is stronger in PPC (especially superficial layers) during deep unconsciousness but stronger in V1 upon awakening. Rostro-caudal (feedback-like) propagation of SWA is state-dependent, particularly in layer 5. Excitability of layer 2/3 neurons, suppressed at high isoflurane, recovers during awakening, when V1 and feedforward pathways reassert a strong role. SWA is a multiscale phenomenon with hierarchical and laminar properties.