SOMATO-DENDRITIC DECOUPLING OF L5 PYRAMIDAL NEURONS ACROSS SLEEP-WAKE STATES

Sleep and general anesthesia both entail a loss of external responsiveness and reduced conscious awareness, yet it is unclear whether they share common cellular mechanisms. The coupling between dendritic and somatic compartments within individual layer 5 (L5) pyramidal neurons may represent a cellular substrate for conscious processing, as these neurons exhibit a compartmentalized architecture in which superficial apical tuft dendrites and deep somata can operate semi-independently to integrate distinct information streams. Indeed, apical dendritic activity in L5 neurons is causally involved in sensory perception, and general anesthesia blocks the propagation of apical dendritic depolarization to the soma. Together, these findings suggest that somato-dendritic decoupling may contribute to anesthesia-induced loss of consciousness. Whether a similar form of somato-dendritic decoupling is a hallmark of sleep remains unknown.
Here, we combined two-photon calcium imaging, Neuropixels recordings, and optogenetic manipulations to study somato-dendritic coupling in mouse somatosensory cortex across sleep–wake states. We find that during REM sleep, apical dendritic calcium activity is significantly reduced, whereas somatic firing rates are preserved or even increased. Furthermore, our results suggest that somato-dendritic decoupling during sleep may arise from NDNF interneuron–mediated suppression of dendritic activity.