Previous studies have shown that the neural mechanisms underlying visual spatial attention rely on top-down control information from the frontal and parietal cortexes, which ultimately amplifies sensory processing of stimulus occurred at the attended location relative to those at unattended location. However, the modulations of effective brain networks in response to stimulus at attended and unattended location are not yet clear. In present study, we collected event-related potentials (ERPs) from 15 subjects during a visual spatial attention task, and a partial directed coherence (PDC) method was used to construct alpha-band effective brain networks of two conditions (targets at attended and nontargets at unattended location). Flow gain mapping, effective connectivity pattern, and graph measures including clustering coefficient (C), characteristic path length (L), global efficiency (E global), and local efficiency (E local) were compared between two conditions. Flow gain mapping showed that the frontal region seemed to serve as the main source of information transmission in response to targets at attended location while the parietal region served as the main source in nontarget condition. Effective connectivity pattern indicated that in response to targets, there existed obvious top-down connections from the frontal, temporal, and parietal cortexes to the visual cortex compared with in response to nontargets. Graph theory analysis was used to quantify the topographical properties of the brain networks, and results revealed that in response to targets, the brain networks were characterized by significantly smaller characteristic path length and larger global efficiency than in response to nontargets. Our findings suggested that smaller characteristic path length and larger global efficiency could facilitate global integration of information and provide a substrate for more efficient perceptual processing of targets at attended location compared with processing of nontargets at ignored location, which revealed the neural mechanisms underlying visual spatial attention from the perspective of effective brain networks and graph theory for the first time and opened new vistas to interpret a cognitive process.

中文翻译：

---

在视觉空间注意任务过程中使用部分定向相干性研究Alpha波段有效脑网络。

先前的研究表明，视觉空间注意力的神经机制依赖于额叶和顶叶皮层的自上而下的控制信息，从而最终放大了相对于无人值守位置发生的刺激的感觉处理。但是，尚不清楚响应于有人照看和无人照管位置刺激的有效大脑网络的调制方式。在本研究中，我们在视觉空间注意任务中收集了15名受试者的事件相关电位（ERP），并使用部分定向相干（PDC）方法构建了两种条件的α波段有效脑网络（目标分别为参加者和参加者）无人参与的非目标）。流量增益映射，有效连接模式以及包括聚类系数（C）在内的图形度量，比较了两个条件下的特征路径长度（L），全局效率（E global）和局部效率（E local）。流量增益映射表明，额叶区域似乎是人们对有人参与目标的响应而传递信息的主要来源，而顶区则是非目标条件下对信息传递的主要来源。有效的连通性模式表明，与对非目标的反应相比，对目标的反应从额叶，颞叶和顶叶皮层到视觉皮层存在明显的自上而下的连接。图论分析用于量化大脑网络的地形特性，结果表明，针对目标，与响应非目标相比，大脑网络的特征在于特征路径长度和全局效率大大降低。我们的研究结果表明，较小的特征路径长度和较大的全局效率可以促进信息的全局集成，并为在照看位置的目标进行有效的感知处理（而不是在忽略位置的非目标）进行处理提供了基础，这揭示了视觉空间注意的潜在神经机制首次从有效的大脑网络和图论的角度出发，开辟了新的视野来解释认知过程。