Intracranial electroencephalography signatures of the induction of general anesthesia with Propofol

Abstract

General anesthesia is a drug-induced, reversible behavioral state characterized by hypnosis (loss of consciousness), amnesia (loss of memory), analgesia (loss of pain perception), akinesia (loss of movement), and hemodynamic stability (stability and control of the cardiovascular, respiratory, and autonomic nervous systems). Each year, more than 25 million patients receive general anesthesia in the United States. Anesthesia-related morbidity is a significant medical problem, including nausea, vomiting, respiratory distress, post-operative cognitive dysfunction, and post-operative recall. To eliminate anesthesia-related morbidity, the brain systems involved in producing general anesthesia must be identified and characterized, and methods must be devised to monitor those brain systems and guide drug administration. A priority for anesthesia research is to identify the brain networks responsible for the characteristic electroencephalography (EEG) signals of anesthesia in relation to sensory, cognitive, memory, and pain systems. In this thesis, we recorded simultaneous intracranial and surface EEG, and single unit data in patients with intractable epilepsy who had been previously implanted with clinical and/or research electrodes. The aims of this research were to characterize the neural signals of anesthesia in a regionally and temporally precise way that is relevant to clinical anesthesia, and to identify dynamic neuronal networks that underlie these signals. We demonstrated region-specific, frequency-band-specific changes in neural recordings at loss of consciousness. We related these findings to theories of how anesthetic drugs may impart their behavioral effects.