Psychophysiological effects of unperceivable stimuli

本研究旨在阐明不可感知刺激对人的心理生理影响，特别是超声对脑电图的影响。实验步骤和结果如下：(1)设备：利用PC-9801 DA微型计算机（NEC）和安装在其中的D/ a转换器的函数发生器（Iwatsu, FG350）产生听觉刺激，函数发生器的输出由音频放大器（DENON PMA390）放大。听觉刺激通过耳机（松下RP-Fl）呈现给受试者。采用脑电图仪（Nihon-kohden EEG-7314）记录脑电图。记录的数据由盒式数据记录器（TEAC R-61）存储在磁带上。(2)听觉刺激呈现：随机呈现200 Hz、2 Khz和20 Khz正弦波三种听觉刺激。演示的持续时间在25到35秒之间（平均= 30见）。ITI也在25 - 35秒之间（平均30秒）。各听觉刺激的振幅均以正弦曲线的形式上升，在触发信号出现后200ms内达到峰值。在刺激偏移处，振幅也以正弦曲线的形式下降，在200msec内达到0点。(3)步骤：在部分隔音电磁屏蔽的房间里，受试者闭着眼睛坐在躺椅上。将Ag/AgCl电极贴于F3、C3、01、A2（参考）点记录EEG。同时记录水平和垂直的眼电和心电，以检查它们在脑电图记录中可能存在的污染。(4)脑电数据分析：从C3点重新编码的脑电振幅数据，每10 msec进行12位数字化。对这些数字化数据进行FFT处理。结果发现，在20 Khz的超声声中，7-8 Hz（慢α）和6-7 Hz（快α）的分量增加。进一步的研究正在进行中，通过增加被试的数量和增加一些控制范式。

This study was conducted to clarify the psychophysiological effects of unperceivable stimuli on human, especially the effects of ultrasonic sound on EEG. Experimental procedures and results obtained are as follows ;(1) Apparatus : Auditory stimuli were generated by a function generator (Iwatsu, FG350) utilizing PC-9801 DA microcomputer (NEC) and D/A converter installed in it Output from the function generator was amplified by an audio amplifier (DENON PMA390). Auditory stimuli were presented to the subuject through a headphone (PANASONIC RP-Fl). EEG was recorded by the Electroencephalography (Nihon-kohden EEG-7314). Recorded data were stored on the magnetic tape by a cassette data recorder (TEAC R-61).(2) Auditory stimulus presentation : Three kinds of auditory stimuli (200 Hz, 2 Khz and 20 KHz sine wave) were presented in a random order. Duration of the presentation was between 25 and 35 sec (mean = 30 see). ITI was also between 25 and 35 sec (mean = 30 sec). Amplitude of each auditory stimulus raised in a form of sinusoid curve reaching its peak within 200 ms after the trigger signal onset. At the offset of the stimulus, the amplitude falled also in a form of sinusoid curve reaching 0 point within 200 msec.(3) Procedure : The subject was seated with his eyes closed on a reclining chair in a partly sound proof - electromagnetic shielded room. Ag/AgCl electrodes were attached to F3, C3, 01 and A2 (reference) points for recording EEG. Horizontal and vertical EOG and ECG were also recorded for cheeking their possible contamination in EEG records.(4) EEG data analysis : Recoded EEG amplitude data from C3 point were digitized in 12 bit everly 10 msec. FFT was performed on these digitized data. It was found that components of 7-8 Hz (slow alpha) and 6-7 Hz (fast rheta) increased as the ultrasonic sound of 20 Khz was presented. Further study in now in pregress, by increasing the number of subjects and adding several control paradigms.