EEG-vigilance regulation: BOLD signal correlations and pathological aspects in psychiatric disorders

Different global functional states of the brain can be separated with electroencephalogram (EEG) not only during sleep (sleep stages 1, 2, 3, NREM and REM sleep) but also during wakefulness under resting conditions (EEG-vigilance stages from full alertness to sleep onset). The development of a computer based algorithm enables a more reliable classification of these EEG-vigilance stages than a visual inspection of EEG data does. These EEG-vigilance stages were used as regressors for the analysis of simultaneous functional magnetic reso-nance imaging (fMRI) and EEG measurements in healthy controls. It has been found that the occur-rence of occipital, parietal and frontal BOLD signal patterns are associated with different EEG vigilance stages. Resting state networks and their temporal dynamics seem to be related to the EEG-vigilance levels. Further, the EEG-vigilance classification has been used to analyze differences in the timecourse of EEG-vigilance stages in patients with obsessive compulsive disorder (OCD), borderline patients and healthy controls. Borderline patients more often exhibit a labile vigilance regulation with a faster vigilance decrease over time than patients suffering from OCD. These results provide evidence that EEG-vigilance stages and the regulation of these functional brain states can be used to investigate pathological mechanisms of vigilance regulation in different psychiatric disorders.