Rihs Tonia A, Michel Christoph M, Thut Gregor
Functional Brain Mapping Laboratory, Department of Neurology, University Hospital Geneva, Switzerland.
Neuroimage. 2009 Jan 1;44(1):190-9. doi: 10.1016/j.neuroimage.2008.08.022. Epub 2008 Aug 28.
Voluntarily directing visual attention to a cued position in space leads to improved processing of forthcoming visual stimuli at the attended position, and attenuated processing of competing stimuli elsewhere, due to anticipatory tuning of visual cortex activity. In EEG, recent evidence points to a determining role of modulations of posterior alpha-band activity (8-14 Hz) in such anticipatory facilitation (alpha-power decreases) versus inhibition (alpha-power increases). Yet, while such alpha-modulations are a common finding, the direction of modulation varies to a great extent across studies implying dependence on task demands. Here, we reveal opposite modulation of posterior alpha-power with early/initiation versus later/sustained processes of anticipatory attention orienting. Marked alpha-decreases were observed during shifting of attention (initial 700 ms) over occipito-parietal areas processing to-be-attended visual space, while alpha-increases dominated in the subsequent maintenance phase (>700 ms) over occipito-parietal cortex tuned to unattended positions. Notably, the presence of alpha-modulation strongly depended on individual resting alpha-power. Overall, this provides further support to an active facilitative versus inhibitory role of alpha-power decreases and increases and suggests that these attention-related changes are differentially deployed during anticipatory attention orienting to prepare versus maintain the cortex for optimal target processing.
通过视觉皮层活动的预期调整，主动将视觉注意力引导至空间中的某个提示位置，会使在被注意位置即将出现的视觉刺激的处理得到改善，而其他位置的竞争性刺激的处理则会减弱。在脑电图中，最近的证据表明，后阿尔法波段活动（8 - 14赫兹）的调制在这种预期促进（阿尔法功率降低）与抑制（阿尔法功率增加）中起决定性作用。然而，虽然这种阿尔法调制是一个常见的发现，但调制的方向在不同研究中差异很大，这意味着它依赖于任务需求。在这里，我们揭示了在预期注意定向的早期/起始过程与后期/持续过程中，后阿尔法功率的相反调制。在将注意力转移（最初700毫秒）到处理待注意视觉空间的枕顶区域期间，观察到明显的阿尔法降低，而在随后的维持阶段（>700毫秒），阿尔法增加在调整到未注意位置的枕顶叶皮层中占主导。值得注意的是，阿尔法调制的存在强烈依赖于个体静息阿尔法功率。总体而言，这进一步支持了阿尔法功率降低和增加的积极促进与抑制作用，并表明这些与注意力相关的变化在预期注意定向过程中被差异地部署，以准备与维持皮层进行最佳目标处理。
