Relations of EEG Patterns with Arousal Level of Rat

Abstract

1. Determination of EEG Patterns in SleepAn experiment was performed to determine relations of EEG patterns in natural sleep with arousal level. 6 male albino rats, 7.5 to 11 months after birth, were used. Stainless steel electrodes were implanted chronically in occipital cortex and hippocampus. EMG recordings were obtained from the neck muscle. By inspection of the polygraphic data based on EEG, EMG and behavior, 7 patterns were classified (Fig. 1). Patterns A and B indicate arousal states. Patterns C and E indicate drowsy or light sleep states. Patterns F and G indicate deep sleep states. Pattern H indicates paradoxical sleep.2. Stimulation ExperimentIn this experiment 4 rats were used. Pure tones (4000 cps, 1 sec. strong = 95 phon, weak =87 phon) were given to the animals when each EEG pattern appeared. It was assumed that tone stimulation would heighten arousal level.Fig. 3 and 4 show EEG pattern change by auditory stimuli during stimulation, post stimulation I (0-3 sec. after stimulation), post stimulation II (3-7 sec. after stimulation). Auditory stimulation changes deep sleep (F, G) and paradoxical sleep (H) EEG patterns to light sleep (C, E) patterns during stimulation or post stimulation I. But during post stimulation II, light sleep patterns changes to deep or paradoxical sleep patterns again.