Abstract
The similarity of sleep and general anesthesia has fascinated scientists for a long time. At first glance, both states are characterized by similar behavioral correlates, namely decreased responsiveness, arousal, and movement. Previously, non-invasive scalp electroencephalographic (EEG) recordings demonstrated highly comparable spectral signatures of both states, such as the ubiquitous presence of slow waves or delta oscillations. More recently, intracranial recordings in humans provided a more fine-grained perspective and revealed that sleep and anesthesia reflect highly distinct entities. Here, we outline how intracranial sleep and anesthesia recordings can be embedded into the clinical routine. We discuss caveats and shortcomings that need to be considered, especially in the context of epilepsy as the underlying neurological disorder. Subsequently, we provide a practical road map to obtain state-specific neural recordings and discuss technical prerequisites as well as important analytical considerations. Finally, we summarize how intracranial recordings extend our understanding about the mechanism-of-action of anesthetic drugs at the network level and to which extent these signatures overlap with physiologic sleep networks. Collectively, here we review how intracranial recordings in humans can be leveraged to gain important insights into sleep physiology and the neural correlates of (un-)consciousness.
