Nogawa T, Katayama K, Tabata Y, Ohshio T, Kawahara T
Electroencephalogr Clin Neurophysiol. 1976 Jan;40(1):78-88. doi: 10.1016/0013-4694(76)90181-4.
Occipital EEG responses to a single photic flash were studied by using a complex demodulation technique. Individual EEGs were first digitally filtered by making use of the Ormsby band-pass filter. Envelopes of the alpha (8-12 c/sec) and of the low frequency (3-7 c/sec) activities were obtained in terms of the demodulation calculation. Both individual and averaged data of raw, filtered, and demodulated EEGs were utilized for the present study. Two typical kinds of EEG responses were observed. One showed clearly the blocking as well as the enhancement of the alpha activity. The alpha activity first exhibited a reduction in amplitude in the range 50-200 msec after the stimulus (the minimum amplitude at about 150 msec). Then an evocation, rather than merely a recovery, of the alpha was observed in the range 500-800 msec (maximum amplitude at about 650 msec). The other typical example showed the low frequency evoked potential prominently. This response appeared almost locked to the stimulus and showed roughly a bi-phasic pattern in the time range where the alpha blocking took place (30-200 msec). Phases of the evoked low frequency component were almost locked to the stimulus but no distinct phase coherence was observed for the enhanced alpha wavetrains. Detection by demodulation of the phase change of the alpha was critical for a single EEG. It is pointed out that changes of the alpha must be studied on individual EEGs.
采用复解调技术研究了枕叶脑电图对单次闪光的反应。首先利用奥姆斯比带通滤波器对个体脑电图进行数字滤波。通过解调计算获得α波（8 - 12次/秒）和低频（3 - 7次/秒）活动的包络。本研究使用了原始、滤波和解调脑电图的个体数据及平均数据。观察到两种典型的脑电图反应。一种清楚地显示了α波活动的阻断以及增强。α波活动在刺激后50 - 200毫秒范围内首先表现出振幅降低（在约150毫秒时振幅最小）。然后在500 - 800毫秒范围内观察到α波的诱发，而不仅仅是恢复（在约650毫秒时振幅最大）。另一个典型例子突出显示了低频诱发电位。这种反应几乎与刺激同步出现，并且在α波阻断发生的时间范围内（30 - 200毫秒）大致呈现双相模式。诱发的低频成分的相位几乎与刺激同步，但增强的α波列未观察到明显的相位相干。对于单个脑电图，通过解调检测α波的相位变化至关重要。指出必须在个体脑电图上研究α波的变化。
