Abstract
The cortical EEGs of the freely behaving cats were analysed by the use of an automatic frequency analyser during the wakefulness-sleep cycle where the three states, arousal, light sleep and paradoxical phase of sleep (PP) were distinguished. The spectral characteristics during PP and those during light sleep were described taking the spectrum during arousal as reference.
1. EEGs during PP: The sensorimotor cortex showed typically an increase of the slow waves (1-12 c/sec) and the fast waves (30-60 c/sec). Mostly the EEG of the auditory cortex behaved similarly. A decrease of the EEG components in the intermediate frequencies was seen in the associative and visual cortices; it occurred in the 10-30 c/sec waves in the visual cortex and in the 14-30 c/sec waves in the associative cortex.
2. EEGs during light sleep: The sensorimotor and auditory cortical EEGs were enhanced in the entire range of frequency below 30 c/sec with a slight decrease in the components faster than 30 c/sec. The visual and associative cortices showed an increase of the wave components slower than 14 c/sec and a decrease of the components in the range of 20-30 c/sec. Their 30-60 c/sec waves did not show a consistent change.
3. It was suggested that the process of activation maintaining “activated” sleep is not complete as in arousal.
