Application of Electroencephalography for Assessing Adaptation Processes in Humans (Review)

Electroencephalography is an informative method for recording the electrical activity of the brain, which is widely used in physiological and clinical studies to assess the functional state of the body. In general, electroencephalography allows to identify characteristic adaptive changes and helps understand the general patterns of compensatory and adaptive responses. This review examines the use of electroencephalography to assess adaptation processes during stress, and cognitive and physical exertion. Currently, neurophysiological diagnostics of stressful conditions is based on the analysis of the main electroencephalogram rhythms: delta (1–4 Hz), theta (4–8 Hz), alpha (8–14 Hz), beta (14–30 Hz), and gamma (>30 Hz), with an assessment of their spectral characteristics (amplitude, dominant frequency, index). Modern research has identified three key electrophysiological correlates of stress: decreased mediofrontal theta activity, modified delta oscillations, and frontal alpha asymmetry. Adaptation to cognitive loads is a crucial mechanism for maintaining mental performance and preventing cognitive fatigue. Electroencephalography allows for an objective assessment of the functional state of cognitive processes, tracking the dynamics of changes in fundamental brain rhythms, and identifying key neurophysiological mechanisms of central nervous system adaptation to various types of mental exercise. This is of significant importance for both fundamental research on cognitive functions and applied aspects of optimizing mental performance. The review shows that the neurophysiological mechanisms of adaptation to physical loads include various complex changes that are clearly reflected in the electroencephalogram. Thus, electroencephalography is an effective tool for assessing not only changes in the brain’s bioelectrical activity, but also the processes of adaptation and recovery during stress, and cognitive and physical exertion.