Intracortical EEG-vigilance stages and the autonomous nervous system

Different functional brain stages during rest can be assessed by electroencephalogram and divided into EEG-vigilance stages. During transition to subvigil stages also the autonomous nervous system (ANS) plays a crucial role in adopting physiological processes. To analyze the association between EEG-vigilance and the activity of the ANS, 15 minutes of resting-EEG in 40 healthy volunteers including measurement of electrocardiogram (ECG), peripheral temperature and skin-conductance level (SCL) were conducted. Vigilance stages were obtained for 2-second segments by assessing the intracortical EEG-power in specified region of interests. The amount of these stages was correlated at interindividual level with parameters of the ANS. Associations at intraindividual level between distinct vigilance stages and ANS parameters were analysed using ANOVA. Results: showed significant positive correlations between amounts of high vigilance stages and SCL and parameters of heart rate variability (HRV). ANOVA revealed significant increased SCL, temperature and pulse frequency during higher vigilance stages in comparison with lower stages. Sympathic activity is dominating during stages of high vigilance. Thus EEG-vigilance stages represent distinct global functional levels of the organism that are not restricted to cortical areas but also affect the ANS. Combined measures of EEG and parameters of the ANS might endorse the power of EEG in controlling effects of e.g. psychopharmacotherapy.