Novel Polygraphic Observations in High Frequency Range during Rapid Eye Movement Sleep

Abstract

EEG activities in the higher frequency range rather than the conventionally used was hypothesized to be more directly related to neurogenic activities which are expected to construct EEG activities. According to this hypothesis, EEG activities up to 90 Hz were measured and analyzed during REM sleep. REM sleep is considered to be only a physiological state which allows one to measure the high frequency EEG activities without contamination of EMG due to muscle atonia except for twitches. The study found that the rhythmic activities with different frequencies randomly appeared one after another in the frequency range up to at least 90 Hz. This result suggests that the rivalry among small neural assemblies activated synchronously is realized during REM sleep, which might be understood within our hypothesized framework of disinhibition and activation associated with REM sleep. In addition, the extremely wide bandwidth of 500 Hz analyzed here disclosed the phasic potentials related to the rapid eye movements which had the consistent topographic pattern, i.e., frontal positive and occipital negative, which suggests the dipole located deep in the brain. This phasic event may be related to a neurogenic potential generating ponto-geniculo-occipital (PGO) wave observed in cats during REM sleep. Therefore, our finding potentially discloses novel aspects of human neurophysiology.