Schadow Jeanette, Lenz Daniel, Thaerig Stefanie, Busch Niko A, Fründ Ingo, Rieger Jochem W, Herrmann Christoph S
Department of Biological Psychology, Otto-von-Guericke University of Magdeburg, Germany.
Int J Psychophysiol. 2007 Oct;66(1):28-36. doi: 10.1016/j.ijpsycho.2007.05.010. Epub 2007 Jun 2.
We studied the effect of different contrast levels on the visual evoked gamma-band response (GBR) in order to investigate whether the GBR is modulated in a similar manner as previously reported for visual evoked potentials. Previous studies showed that the GBR can be modulated by individual characteristics (age) and experimental conditions (task difficulty, attention). However, stimulus properties, such as size and spatial frequency, also have a large impact on the GBR, which necessitates identification and control of relevant stimulus properties for optimal experimental setups. Twenty-one healthy participants were investigated during a forced-choice discrimination task. Sinusoidal gratings were presented at three contrast levels with a constant spatial frequency of 5 cycles per degree visual arc (cpd). The present data replicate the results reported for visual evoked potentials and exhibit a contrast dependent modulation of the GBR. Gamma activity is increased for higher contrast levels. These results demonstrate the importance of stimulus contrast for evoked gamma activity. Thus, it appears meaningful to control the contrast of stimuli in experiments investigating the role of gamma activity in perception and information processing.
我们研究了不同对比度水平对视觉诱发伽马波段反应（GBR）的影响，以探究GBR是否像先前报道的视觉诱发电位那样以类似方式受到调制。先前的研究表明，GBR可受个体特征（年龄）和实验条件（任务难度、注意力）的调制。然而，诸如大小和空间频率等刺激特性也对GBR有很大影响，这就需要识别和控制相关刺激特性以实现最佳实验设置。在一项强制选择辨别任务中对21名健康参与者进行了研究。以每度视角5周/度（cpd）的恒定空间频率呈现正弦光栅，对比度水平分为三种。目前的数据重复了视觉诱发电位的报道结果，并显示出GBR的对比度依赖性调制。较高对比度水平下伽马活动增加。这些结果证明了刺激对比度对诱发伽马活动的重要性。因此，在研究伽马活动在感知和信息处理中的作用的实验中，控制刺激对比度似乎是有意义的。
