BRAIN MECHANISMS OF VISUAL SELECTIVE ATTENTION

本项目的目标是研究神经机制。 选择性注意和注意定向在患者中的作用 局灶性皮质损伤或完全脑连合切断术，以及 正常对照受试者。在一系列实验中，该项目将 研究调节选择性注意到空间的大脑系统 位置，到不同类别的刺激特征，如颜色， 移动和空间频率，以及特征的连接 (对象)。来自动物和人类研究的证据表明， 顶叶皮质主要参与空间认知的各个方面 而次颞叶投影系统参与了 刺激特征和对象的表示。我们假设， 在某种程度上，注意力选择调节大脑皮层区域的活动。 编码特定的视觉特征或维度，因此我们 预测注意的空间方面需要注意的完整性 当注意特征和物体时，顶叶皮质是一种 枕-颞下投射通路。此外，它一直是 假设两个半球的差异专门化 存在基于空间与基于特征和基于对象的感知 左半球偏向于对象表征，而右半球偏向于对象表征 半球是空间加工的主导者。我们将利用 注意力的行为测量(反应时间和准确度)和 顶叶和下叶的电生理测量(即事件相关电位) 单纯性顶叶患者的时间视觉加工研究 与左侧和右侧颞顶皮质病变的对比 大脑半球来研究这些脑区在空间， 基于特征和基于对象的注意力。连合切开术的研究 患者还将研究假想的半球不对称。 在空间和基于对象的选择性注意中，以及半球 在全球和地方层面的处理方面的专业化 刺激物。大脑皮质下和大脑皮层相互作用的研究 关注联合切开患者将继续我们在这方面的工作 区域。先前的结果表明，在许多情况下， 联合切开术患者皮质分离的大脑半球可以发挥作用 在视觉搜索大型阵列中的目标项期间独立 干扰物，同时继续表现为大脑半球间 知觉-运动加工中的相互作用。我们会尝试找出 决定两个大脑的关键条件 在注意处理过程中，大脑半球可以独立运作。 这些研究将有助于识别大脑皮层系统和半球 注意加工的专门化及其贡献 皮层下系统对注意过程整合的影响 人脑。

The goals of the present project are to investigate the neural mechanisms of selective attention and attention orienting in patients with either focal cortical damage or complete cerebral commissurotomy, as well as in normal control subjects. In a series of experiments this project will investigate the brain systems that mediate selective attention to spatial locations, to different classes of stimulus features such as color, movement and spatial frequency, and to conjunctions of features (objects). Evidence from animal and human studies indicate that the parietal cortex is principally involved in aspects of spatial cognition while the inferotemporal projection system is involved in the representation of stimulus features and objects. We hypothesize that, in part, attentional selection modulates activity in the cortical areas that code a particular visual feature or dimension, and we therefore predict that spatial aspects of attention require the integrity of the parietal cortex while attention to features and objects is a function of the occipito-inferotemporal projection pathway. Moreover, it has been hypothesized that differential specializations of the two hemispheres for spatial versus feature- and object-based perception exist such that the left hemisphere is biased towards object representation while the right hemisphere is dominant for spatial processing. We will utilize behavioral measures of attention (response time and accuracy) and electrophysiological measures (i.e., ERPs) of parietal and infero- temporal visual processing in studies of patients with parietal-only versus temporo-parietal cortex lesions of both the left and right hemispheres to investigate the role of these brain areas in spatial, feature-based, and object-based attention. Studies in commissurotomy patients will also investigate the hypothesized hemispheric asymmetries in spatial and object-based selective attention, as well as hemispheric specializations in the processing of global versus local levels of stimuli. Investigations of subcortical and cortical interactions during attention in the commissurotomy patients will continue our work in this area. Previous results have demonstrated that under many conditions the cortically separated hemispheres of commissurotomy patients can act independently during visual search for target items in large arrays of distractors, while continuing to demonstrate interhemispheric interactions in perceptual-motor processing. We will attempt to identify the critical conditions that determine whether or not the two cerebral hemispheres can perform independently during attentional processing. These studies will help to identify cortical systems and hemispheric specializations in attentional processing as well as the contributions of subcortical systems to the integration of attentional processes in the human brain.