Similarities and differences between natural sleep and urethane anesthesia.

Slow oscillations in the brain’s parietal cortex during urethane anesthesia differ fundamentally from those during natural non-REM sleep in mice, despite appearing similar on the surface. Differences are evident in the local field potential, the underlying current sources, and the modulation of unit activity. The data show that slow network oscillations in natural sleep and anesthesia are generated by different mechanisms, challenging the assumption that anesthesia reliably models sleep-related brain activity. This work highlights that phenomenological similarities can mask distinct neural processes, with implications for using anesthesia as a model for sleep and consciousness studies.

Study at a glance

Abstract

Slow oscillations dominate the EEG or local field potential (LFP) of mammals during specific periods within natural sleep and anesthesia. Such similarities have led to the use of anesthesia as a model to study sleep and state-dependent changes of consciousness. Previous research has documented the similarities between the activated state of urethane anesthesia and natural REM sleep, particularly with respect to network oscillations in the theta (θ) frequency domain. Likewise, the deactivated states, characterized by large amplitude slow waves in both urethane anesthesia and non-REM sleep, have generally been regarded as similar. Here, we report striking differences between slow oscillations in the mouse parietal cortex during the deactivated state of urethane anesthesia and natural non-REM sleep. These differences are notable in the LFP, the underlying current sources, and in the modulation of unit activity. Our data show that slow network oscillations in natural sleep and anesthesia are generated by different mechanisms, despite phenomenological similarities.