Boon Mei Ying, Chan Kar Ying, Chiang Jaclyn, Milston Rebecca, Suttle Catherine
School of Optometry and Vision Science, University of New South Wales, UNSW, Sydney, NSW, 2052, Australia.
Doc Ophthalmol. 2011 Apr;122(2):99-113. doi: 10.1007/s10633-011-9264-3. Epub 2011 Mar 3.
Transient chromatic pattern visual evoked potentials (VEPs) have been found to be less repeatable in morphology in children than in adults at low to moderate chromatic contrasts. The purpose of this study is to investigate whether low repeatability of VEP components can be associated with high alpha power, in a comparison of alpha activity in children and adults. Transient chromatic contrast and achromatic resolution VEPs were recorded in children (n = 14, mean 9.6 years) and adults (n = 12, mean 21.8 years) with normal vision and assessed for repeatability. Isoluminant chromatic (magenta-cyan) and luminance-modulated achromatic grating stimuli were presented at and above psychophysical threshold levels, in pattern onset-offset at 2 Hz temporal frequency. EEGs (eyes closed and open) were recorded as single sweeps (1 s long) over three 30 s periods while facing a uniform computer display. An index of VEP detectability by observation was developed based on VEP component repeatability. The index was examined for correlations with alpha-wave parameters. Alpha power was calculated as the sum of the powers of 8-13 Hz frequencies of the EEG sweeps (using the discrete Fourier transform). Alpha power variability was calculated using the standard deviation of the powers of each sweep in a 30 s time period. The children had significantly higher alpha powers than the adults for both the eyes-open and eyes-closed conditions. Alpha power variability was significantly higher for the eyes-open condition only. There was no relationship between alpha power parameters and index of VEP detectability by observation for both the chromatic and achromatic grating stimuli. Poor repeatability of transient pattern VEPs is not associated with high alpha power or its variability in EEG measurements in older children or young adults at Oz.
已发现，在低至中等色度对比度下，儿童的瞬态彩色模式视觉诱发电位（VEP）在形态上的可重复性低于成人。本研究的目的是在比较儿童和成人的阿尔法活动时，调查VEP成分的低可重复性是否与高阿尔法功率有关。对视力正常的儿童（n = 14，平均9.6岁）和成人（n = 12，平均21.8岁）记录瞬态色度对比度和消色差分辨率VEP，并评估其可重复性。在2Hz时间频率的模式起始-偏移中，以高于心理物理学阈值水平呈现等亮度彩色（品红色-青色）和亮度调制的消色差光栅刺激。在面对均匀的电脑显示屏时，在三个30秒时间段内将脑电图（闭眼和睁眼）记录为单次扫描（1秒长）。基于VEP成分的可重复性开发了一个通过观察来检测VEP的指标。检查该指标与阿尔法波参数的相关性。阿尔法功率计算为脑电图扫描8 - 13Hz频率功率之和（使用离散傅里叶变换）。阿尔法功率变异性使用30秒时间段内每次扫描功率的标准差来计算。在睁眼和闭眼条件下，儿童的阿尔法功率均显著高于成人。仅在睁眼条件下，阿尔法功率变异性显著更高。对于彩色和消色差光栅刺激，阿尔法功率参数与通过观察检测VEP的指标之间均无关系。在较大儿童或年轻成人的Oz脑电图测量中，瞬态模式VEP的可重复性差与高阿尔法功率或其变异性无关。
