The role of alpha rhythm in sensory input control during selective attention

本项目的最终目标是研究控制选择性注意的神经系统，特别是EEG α振荡，早期视觉处理和刺激后处理在更高的皮层区域之间的相互作用的时间动态。为此，我们解剖这些机制之间的相互作用，在阿尔法脑电调制，感觉增益控制，视觉通路和事件相关电位。在第一个任期内的补助金，我们采用了经典的波斯纳型空间注意力设计，并发现α振荡和稳态视觉诱发电位（SSVEPs），早期视觉处理的标记之间没有相关性。此外，我们进行了三个视觉搜索实验中，我们发现了预期的α desertification和增加SSVEP振幅沿着与N2pc的目标刺激。有趣的是，虽然分心刺激引起了一个Pd，一个标记的主动刺激抑制，α表现出更大的desertification在电极对侧的分心，和SSVEP振幅增加或显示没有差异相对于刺激前的基线。这些发现，连同其他最近的发现，质疑阿尔法作为一个积极的（自上而下）刺激抑制的神经机制的作用。在未来，我们打算进一步阐述这些意想不到的结果在视觉搜索的分心处理，并将扩大我们的研究范围，包括基于特征的选择性注意以及基于空间的注意设计。 特别是，阿尔法调制在功能为基础的注意力的功能作用，将调查的范例，操纵注意力负荷和促进颜色处理全球整个视野。我们相信，我们的研究结果将大大有助于理解视觉选择性注意的神经系统，并可能会质疑一些已建立的α振荡在注意力中的作用模型。

The ultimate goal of the present project is to investigate the neural systems that control selective attention, in particular the temporal dynamics of the interaction between EEG alpha oscillations, early visual processing and post-stimulus processing in higher cortical areas. To this end, we dissect these mechanisms by looking at the interactions between alpha EEG modulation, sensory gain control, and event-related potentials in the visual pathways. During the first tenure of the grant we employed a classical Posner type spatial attention design and found no correlation between alpha oscillations and steady state visual evoked potentials (SSVEPs), a marker of early visual processing. Further, we conducted three visual search experiments, in which we found the to-be-expected alpha desynchronization and increase of SSVEP amplitudes along with an N2pc for target stimuli. Interestingly, although distractor stimuli elicited a Pd, a marker for pro-active stimulus suppression, alpha exhibited greater desynchronization at electrodes contralateral to the distractor, and SSVEP amplitudes either increased or showed no difference relative to a pre-stimulus baseline. These findings, together with other recent findings, question the role of alpha as a neural mechanism for active (top-down) stimulus suppression. In the future we intend to further elaborate on these unexpected results regarding distractor processing in visual search and will expand the scope of our studies to include feature-based selective attention as well as spatial-based attentional designs. In particular, the functional role of alpha modulations in feature-based attention will be investigated in paradigms that manipulate attentional load and facilitate color processing globally throughout the visual fields. We are convinced that our results will contribute significantly to the understanding of the neural systems that underlie visual selective attention and might call into question some of the established models of the role of alpha oscillations in attention.