1980 Volume 23 Issue 3 Pages 159-164
Slow vertex responses evoked by pure tone acoustic stimuli were recorded in 4 young adults with normal hearing acuities under natural sleep. The acoustic stimuli of pure tone were given by 20dB above their thresholds. All trials in one person were carried out every 5 minutes constantly, and background EEG was monitered and the stages of sleep were determined according to the criteria of Dement & Kleitman. The sleep was induced naturally without any medication in all examinations.
The results were as follows;
1) The most clear and fine waves of averaged responses with the largest N1-P2 amplitudes and the shortest N1-N2 intervals were recorded in awake conditions. The morphology of averaged waves became more unclear as the stage of sleep getting deeper.
2) The averaged responses recorded during change of sleep stage in one trial showed more obscure morphology: longer N1-N2 intervals and smaller N1-P2 amplitudes.
3) In the pure tone stimuli just above the hearing threshold, P2-N2 amplitudes decreased with deepening of the sleep stage.
4) In the examinations with acoustic stimuli, it was difficult to keep the sleep stage 4 constant even in one trial, and this might be caused by the acoustic stimuli.
