Imbalance of Neuronal Activity as the Underlying Principle of Unconsciousness in Sleep and General Anesthesia

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Unconsciousness is part of our daily life: We experience it during sleep, which constitutes about one third of our lives, or as general anesthesia during a surgical procedure. Sleep is a natural state induced by the brain itself and is vital for a healthy mind and body - without sleep we die. Anesthesia, on the other hand, is an artificial 'sleep' that keeps us unaware of our surroundings, oblivious to painful stimuli and hinders us from forming new memories. While sleep has positive effects on our cognitive abilities, a deep anesthesia can even be harmful. Although both states of unconsciousness play such an important role in our lives, the underlying neuronal principles remain poorly understood and it is still unclear how much these states have in common. Here, we aim to differentiate distinct neuronal states of unconsciousness by comparing network activity in waking, sleep and general anesthesia within the same patient. We will test if unconsciousness is the result of an imbalance of neuronal activity on the I) local (within one area) or II) global (between different areas) level. To achieve these goals, we will take advantage of the excellent spatiotemporal resolution of intracranial recording in patients who suffer from pharmacoresistant epilepsy. These recordings provide detailed insights into brain dynamics not only on the surface but also within deep brain structures.The proposed project will advance our understanding of the neurophysiological basis of altered states of consciousness with extensive implications for both basic as well as translational sciences. The outcomes of this study will be of clinical use and can help to improve neuromonitoring in anesthesia and intensive care and by that reduce the incidence of side effects like intraoperative awareness or postoperative cognitive decline. Furthermore, they will enhance sleep monitoring (e.g. in a laboratory) and make sleep scoring easier and more accurate. The new insights from this study may shed new light on the basis of other altered forms of consciousness (e.g. coma, vegetative state, postictal state or absence epilepsy) and could thereby help to develop novel therapeutic strategies.