Abteilung Allgemeine Psychologie, Justus-Liebig-Universitat, Otto-Behaghel-Str. 10, 35394, Giessen, Germany.
Exp Brain Res. 2010 Dec;207(3-4):213-9. doi: 10.1007/s00221-010-2444-7. Epub 2010 Oct 24.
Alpha waves are traditionally considered a passive consequence of the lack of stimulation of sensory areas. However, recent results have challenged this view by showing a modulation of alpha activity in cortical areas representing unattended information during active tasks. These data have led us to think that alpha waves would support a 'gating function' on sensorial stimulation that actively inhibits unattended information in attentional tasks. Visual suppression occurring during a saccade and blink entails an inhibition of incoming visual information, and it seems to occur at an early processing stage. In this study, we hypothesized that the neural mechanism through which the visual system exerts this inhibition is the active imposition of alpha oscillations in the occipital cortex, which in turn predicts an increment of alpha amplitude during a visual suppression phenomena. We measured visual suppression occurring during short closures of the eyelids, a situation well suited for EEG recordings and stimulated the retinae with an intra-oral light administered through the palate. In the behavioral experiment, detection thresholds were measured with eyes steady open and steady closed, showing a reduction of sensitivity in the latter case. In the EEG recordings performed under identical conditions we found stronger alpha activity with closed eyes. Since the stimulation does not depend on whether the eyes were open or closed, we reasoned that this should be a central effect, probably due to a functional role of alpha oscillation in agreement with the 'gating function' theory.
阿尔法波传统上被认为是感官区域缺乏刺激的被动结果。然而，最近的结果通过显示在主动任务中代表未被注意信息的皮质区域中阿尔法活动的调制，挑战了这一观点。这些数据使我们认为阿尔法波将支持感觉刺激的“门控功能”，在注意力任务中主动抑制未被注意的信息。在扫视和眨眼过程中发生的视觉抑制需要抑制传入的视觉信息，并且似乎发生在早期处理阶段。在这项研究中，我们假设视觉系统施加这种抑制的神经机制是在枕叶皮层中主动施加阿尔法振荡，这反过来又预测在视觉抑制现象期间阿尔法振幅的增加。我们测量了眼睑短暂闭合期间发生的视觉抑制，这种情况非常适合 EEG 记录，并通过通过 palate 施加的口腔内光刺激视网膜。在进行的行为实验中，通过稳定睁开和稳定闭上眼睛来测量检测阈值，在后者情况下显示出敏感性降低。在相同条件下进行的 EEG 记录中，我们发现闭眼时的阿尔法活动更强。由于刺激不取决于眼睛是睁开还是闭上，我们推断这应该是一种中枢效应，可能是由于阿尔法振荡在与“门控功能”理论一致的功能作用。
