Alpha Oscillations Correlate with the Successful Inhibition of Unattended Stimuli
Alpha Oscillations Correlate with the Successful Inhibition of Unattended Stimuli
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DOI：
10.1162/jocn.2010.21557
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发表时间：
2011-09-01
影响因子：
3.2
通讯作者：
Jensen, Ole
中科院分区：
文献类型：
--
作者：
Handel, Barbara F.;Haarmeier, Thomas;Jensen, Ole
因为人类的视觉系统不断受到输入的轰炸，所以有必要有有效的机制来过滤掉不相关的信息。这在一定程度上是通过分配注意力来实现的，它允许视觉系统处理相关的输入，同时屏蔽不相关的输入。注意分配的生理基础是什么？有人提出α活性反映了功能抑制。在这里，我们询问α振荡的抑制是否对抑制无人参与输入的感知具有行为后果。为此，我们利用脑磁图研究了两种注意力状态下α活动对运动加工的影响。所使用的视觉刺激包括两个随机点运动图，同时呈现在左右视觉半球。受试者被提示暗中观看左或右运动学图。1.5秒后，第二个线索测试被试是否能报告在有人参与的半场（80%）或无人参与的半场（20%）中连贯运动的方向。枕叶α功率对侧高于对侧，提示对侧抑制。我们的主要发现是，在20%的无效提示试验中，这种α偏侧化确实与运动方向的感知相关：在无人看管的半场中，α偏侧化明显的受试者在检测运动方向方面更差。相比之下，侧化与参与的视觉半球的视觉辨别无关。我们的研究结果强调了α振荡的抑制性，并表明α活动的增加削弱了对注意力领域之外输入的处理。
Because the human visual system is continually being bombarded with inputs, it is necessary to have effective mechanisms for filtering out irrelevant information. This is partly achieved by the allocation of attention, allowing the visual system to process relevant input while blocking out irrelevant input. What is the physiological substrate of attentional allocation? It has been proposed that alpha activity reflects functional inhibition. Here we asked if inhibition by alpha oscillations has behavioral consequences for suppressing the perception of unattended input. To this end, we investigated the influence of alpha activity on motion processing in two attentional conditions using magneto-encephalography. The visual stimuli used consisted of two random-dot kinematograms presented simultaneously to the left and right visual hemifields. Subjects were cued to covertly attend the left or right kinematogram. After 1.5 sec, a second cue tested whether subjects could report the direction of coherent motion in the attended (80%) or unattended hemifield (20%). Occipital alpha power was higher contralateral to the unattended side than to the attended side, thus suggesting inhibition of the unattended hemifield. Our key finding is that this alpha lateralization in the 20% invalidly cued trials did correlate with the perception of motion direction: Subjects with pronounced alpha lateralization were worse at detecting motion direction in the unattended hemifield. In contrast, lateralization did not correlate with visual discrimination in the attended visual hemifield. Our findings emphasize the suppressive nature of alpha oscillations and suggest that processing of inputs outside the field of attention is weakened by means of increased alpha activity.