Parameter-based assessment of visual attention: functional neuroanatomy, timing and interference

无论从基础视觉神经学的角度还是从临床神经学的角度，理解视觉空间注意的机制都具有特别重要的意义，因为注意在空间中的分配是与视觉环境有效互动的先决条件。这项建议的目的是通过结合行为测量、功能磁共振成像(FMRI)和有效连接分析来提供自上而下和自下而上过程的进一步证据。在一系列先导实验的基础上，将检验几个假设，根据的基本假设是，如果目标分布在半个领域，则注意力焦点可以分散。在与事件相关的参数设计中，我们将分析行为测量(反应时间和错误率)与早期视觉和顶叶皮质区域的血流动力学反应之间的相关性。我们的方法具有几个优势，这些优势超出了以前在该领域的工作；i)它允许对提示期和目标选择期以及它们在每个视网膜感兴趣区(ROI)内的相关激活进行单独分析；ii)改变目标的显著程度将使我们能够检查任务难度效应及其对提示期和目标选择期的影响；iii)对多个ROI之间连接的注意调制的分析将允许量化早期视觉区域内以及早期视觉区域与顶叶和额叶皮质区域之间的神经交互的上下文变化。

Understanding the mechanisms of visuo-spatial attention is of particular importance both from the perspective of basic visual neuroscience and from the perspective of clinical neurology; as the allocation of attention in space is a prerequisite for the effective interaction with our visual environment. The aim of this proposal is to provide further evidences of top-down and bottomup process by combining behavioural measures, functional magnetic resonance imaging (fMRI) and the analysis of effective connectivity. Based on a series of pilot experiments several hypotheses will be tested, according to the basic assumption that the focus of attention can be split if targets are distributed across hemifields. In an event-related parametric design we will analyze the correlation between behavioural measures (reaction times and error rates) and the hemodynamic response of early visual and parietal cortical areas. Our approach has several advantages, which go beyond previous work in the field; i) it allows a separate analysis of the cueing period and the target selection period and their related activation within each of the retinotopic regions of interest (ROIs), ii) varying the saliency of targets will allow us to examine task difficulty effects and their impact on the cueing period and the target selection period, iii) the analysis of the attentional modulation of connectivity between multiple ROIs will allow quantification of contextual modifications of neural interactions within early visual areas as well as between early visual areas and areas in parietal and frontal cortex.