DEPTH-ELECTROENCEPHALOGRAMS OF CHICKENS IN WAKEFULNESS AND SLEEP

Spontaneous EEG activities of the hyperstriatum accessorium, archistriatum, paleostriatum augmentatum and primitivum, dorsal and ventral hippocampus, area entorhinalis, area paraentorhinalis, and optic tectum were recorded simultaneously in unanaesthetized chickens during sleep and wakefulness and subjected to frequency analyses. The results obtained are as follows. 1. No regular slow waves such as seen in the hippocampus of mammals during arousal and paradoxical sleep were observed in the hippocampus of chickens. 2. No high-voltage fast waves appeared in the archistriatum during arousal. 3. Regular alpha-like waves of 8-13 Hz appeared in the paleostriatum primitivum during slow-wave sleep. 4. In association with rapid eye movements, monophasic spikes were recorded in the optic tectum of chickens during the paradoxical-sleep phase. 5. Frequency analyses revealed that the EEGs of the hyperstriatum accessorium of chickens during arousal and paradoxical sleep contained more developed components of slow waves than in the EEGs of the neocortex of mammals.