A study of EEG activities during sleep-wakefulness states in rabbits by autocorrelation and power spectrum analyses.

A polysomnography was performed on nine rabbits with electrodes chronically implanted at the sensorimotor and visual corticies and hippocampus. The physiological sleep of the rabbits was divided into three stages: awake (W), slow wave sleep (SWS) and REM sleep (REM). For autocorrelation and power spectrum analyses, a transitional zone (T) from W to SWS was added to the fundamental three stages. No essential differences between the mean frequencies of the cortical and hippocampal EEGs were seen. The mean frequencies of hippocampal EEG were as follows: 6.4 in W, 5.4 and 2.4 in T, 2.2 in SWS and 7.3 Hz in REM. The mean peak frequency of hippocampal EEG during REM was significantly higher than that during W.