Dissociating Components of the Attentional Network in Neglect

描述（由申请人提供）：中风后的脑损伤影响了许多美国人，对生活质量和进行日常生活活动的能力产生重大影响。为了尽量减少中风对人类和经济的影响，需要了解预测康复和成功康复的因素。视觉忽视是右半球脑损伤的常见后果，这种症状（或综合征）的存在是不良临床结果的主要预测因素。视觉忽视是一种临床注意力缺陷，患者无法注意到或对病灶对面的事物做出反应。因此，一个右半球中风的人可能只吃盘子的右手边，忽略左边的食物，或者可能只刮右脸的胡子，等等。人们对忽视进行了多年的研究，部分原因是它具有重要的临床意义，但也因为它有可能为研究大脑的注意力机制提供洞见。最常见、最严重、最持久的忽视是右半球受损，导致左半球被忽视。右侧忽视的存在更具争议性，临床意义较小。由于这些原因，目前的研究仅限于右半球损伤引起的左忽视的研究。关于忽视的两个最基本的问题仍然没有答案，也是科学文献中深刻争议的主题。简单地说，就是：赤字的本质是什么？导致忽视的脑损伤的关键区域是什么？我们提出一个简单的理论框架来回答这些问题，并为注意力的不同观点提供和解。我们认为，视觉忽视是一种复杂的综合征，尽管如此，它仍可分解为一系列缺陷，这些缺陷是由大脑皮层四个区域的损伤或功能障碍造成的。这四个皮层区域代表了大脑注意力网络中离散但相互关联的模块。顶叶内沟是一个参与决定事物整体结构并对其作出反应的区域；该区域的损伤与线对分任务中的偏差有关。颞盖和脑岛（一个通常被称为颞上回的区域）参与了对物品的定位；该区域的损坏将导致在线取消任务出错。颞顶叶交界参与分配物品的显著性；对该区域的损害将导致视觉消失——只有在良好视野中有物体时，才无法报告受损视野中的物体。最后，额叶视野是主要与知觉抑制有关的区域；对这一区域的破坏会导致注意力更加分散。我们认为，关于核心区域和症状的争议是由于这四个系统受损的患者取样的可变性。本研究通过神经心理学、功能性核磁共振成像和经颅磁刺激在正常观察者身上的融合使用来测试这些预测。

DESCRIPTION (provided by applicant): Brain damage following stroke affects many Americans, having a major impact on quality of life and the ability to carry out activities of daily life. To minimize the human and economic impact of stroke, the factors that predict recovery and successful rehabilitation need to be understood. Visual neglect is a common consequence of brain damage to the right hemisphere, and the presence of this symptom (or syndrome) is a major predictor of poor clinical outcomes. Visual neglect is a clinical deficit of attention, in which the person fails to notice, or to respond to items opposite the lesion. So a person with a stroke to the right hemisphere may eat from only the right hand side of their plate, ignoring the food on the left, or may shave only the right side of their face, and so on. Neglect has been studied for many years, in part for its major clinical significance, but also because it has the potential to provide insight into brain mechanisms of attention. The most common, severe and enduring neglect follows damage to the right hemisphere, leading to neglect of the left. The presence of right neglect is more controversial, and of lesser clinical significance. For these reasons, the present study is confined to studies of left neglect due to right hemisphere damage. The two most fundamental questions about neglect remain unanswered, and the subject of deep controversy in the scientific literature. Simply stated, these are: what is the nature of the deficit? and what are the key areas of brain damage that cause neglect? We propose a simple theoretical framework for answering these questions and providing rapprochement for the divergent views of attention. We propose that visual neglect is a complex syndrome that is nonetheless dissociable into sets of deficits that result from damage to, or dysfunction of, four regions of the cortex. These four cortical regions represent discreet, yet interconnected modules in the attentional network of the brain. The intraparietal sulcus is a region involved in determining the global structure of items, and responding to them; damage to this region is associated with bias on the line bisection task. The temporal operculum and insula (a region often referred to as superior temporal gyrus) is involved in orienting to items; damage to this region will lead to errors on the line cancellation task. The temporoparietal junction is involved in assigning salience to items; damage to this region will lead to visual extinction - a failure to report items in the impaired visual field only if there are items in the good field. Finally the frontal eye fields are regions primarily concerned with perceptual inhibition; damage to this region will lead to increased distractibility. We propose that the controversies over the core areas and symptoms are due to variability in sampling patients with damage to these four systems. The present study tests these predictions by converging use of neuropsychology, functional MRI, and transcranial magnetic stimulation in normal observers.