入眠時緩徐眼球運動のDC記録とAC記録の比較

Following a brief review of eye movements in terms of mental activities and a technology of electro-oculograph (EOG), this study demonstrated slow eye movements (SEMs) in a transition from wakefulness to sleep by comparing DC and AC EOG recordings, and examined the distortions introduced into AC EOGs. Simultaneous recordings were made of EEG (C4/A1), EOGs (E1/A1 & E2/A1) and respiration in ten female subjects. Nonpolarizable Ag/Agcl electrodes were attached to the skin near outer canthi of eyes. Skin resistances were less than 5Kohm. Time constants for EOG channels were DC and 2sec. After controlled pursuit eye movements were tested by tracking targets at .2Hz and .5Hz, subjects lay in bed and slept 60 minutes. Two types of SEMs were differentiated: a continuous series of SEMs (burst type) and individually separated ones (single type). Burst SEMs were frequent and predominant early in a transition from wakefulness to sleep, while single SEMs appeared before an actual onset of sleep. Excursions of SEMs ranged in a swing from 1 to 16sec (mode: 2-3sec). There was a marked attenuation of AC recordings as the swing of SEMs became longer than 10sec. Such distortions were evident for single SEMs and during sleep The quantitative assessment of distortions of SEM wave forms was made in three subjects by computing product moment correlation coefficients between DC and AC EOG recordings. High correlations were consistently yielded for the controlled slow pursuit movements. SEMs showed a large variation of correlation coefficients ranging from .2 to .9, thus suggesting that the present time constant 2sec might not be sufficient to reproduce DC signals. Recommendable values of time constant for sleep EOG recording should be longer than 4sec, for lower cut-off frequencies are expected to be low enough to follow SEMs. EOGs during slow wave sleep showed no eye movements but contaminates coming from EEG slow components, that could not support Dement\u27s expectation concerning the possibility of the slowest SEMs in deep sleep