CORTICAL AND SUBCORTICAL EEG IN RELATION TO SLEEP-WAKE BEHAVIOR IN MAMMALIAN-SPECIES

In humans and several other mammals, a quantitative EEG analysis has b een used to study the regulation of sleep-wake behavior. In all mammal ian species studied, cortical EEG recorded during non-REM sleep (NREMS ) is characterized by the occurrence of spindles and high voltage, slo w waves (0.5-4.0 Hz). Furthermore, slow-wave activity (SWA) is low at the beginning of a NREM episode and it rises in the course of a NREM e pisode. The rise rate and the maximal level of SWA are a monotonic fun ction of the duration of prior wakefulness. During REMS, cortical EEG typically exists of low-voltage, mixed frequencies and, in some animal s, a prominent theta rhythm is superimposed. Only after sleep deprivat ion in some species does cortical EEG within REMS change. Especially, the EEG activity during wakefulness depends considerably on the behavi oral state, on the electrode location and on the species. On average, cortical EEG within wakefulness consists of low-voltage, mixed frequen cies. The few studies done on subcortical EEG clearly show that the el ectrical activity differs highly between brain regions and between spe cies. However, two recent studies, in which a spectral analysis of sub cortical EEG was made, showed that, at least in humans and cats, the c hanges occurring in subcortical EEG associated with changes in sleep-w ake behavior parallel the general characteristics of cortical EEG desc ribed above.