EEG Brain Connectivity Analysis: Sleep Staging and Anesthetic Depth

Abstract

The brain, as the central organ of the nervous system, performs a wide array of functions through its intricate neural network and chemical activities. These functions encompass essential aspects of life, including learning, memory, emotion regulation, perception, and motor control, and are closely tied to various physiological and neurological processes that govern human behavior and survival. To explore the brain, a multitude of medical devices have been developed, such as magnetic resonance imaging (MRI), computed tomography (CT), electroencephalography (EEG), and more. EEG, in particular, records electrical changes associated with brain activity and has found extensive use in various fields of brain research. Furthermore, it is increasingly employed in both medical applications, like the diagnosis of abnormal brain activity (e.g., epilepsy), and in real-life contexts, such as Brain-Computer Interfaces (BCI). This paper aims to quantitatively evaluate brain activity by acquiring EEG data using EEG equipment and employing brain connectivity analysis to examine the flow of brain information during states of altered consciousness (anesthesia and sleep). The objective is to provide a quantitative analysis of brain activity during altered states of consciousness. In Part 1, we investigate the patterns of brainwave changes associated with different sleep stages through brain connectivity analysis, with the goal of identifying indicators for accurate sleep stage assessment. Furthermore, we seek to implement a deep learning model for sleep stage classification, potentially replacing manual sleep stage scoring by sleep experts. In Part 2, we analyze changes in brain connectivity resulting from variations in anesthesia depth, aiming to identify precise features related to the depth of anesthesia. Typically, devices like the Bispectral Index (BIS) monitor anesthesia states, and this study explores the potential of using brain connectivity as an indicator of anesthesia depth, akin to BIS and other anesthesia monitoring tools.