FUNCTIONAL MAPPING OF HUMAN VISUAL CORTEX

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。这个持续项目的长期目标是开发和应用功能磁共振成像（fMRI）技术来研究和表征负责正常视觉感知和注意力的神经机制。该项目将专注于开发一套神经生理学原理，以表征人类皮层视觉处理的注意力相关控制。（1,2）在两组初始实验中，将对两种基于fmri的皮质活动测量方法进行严格评估，以确定其准确反映注意力行为影响的能力。我们将检验这些方法在三种不同类型的注意力密集型任务（绝对检测、增量检测和特征连接检测）下准确描述注意力强度和地形特性的能力。我们假设这些测量将反映任务的特定注意力需求。(3)接下来，这些措施将被用于观察注意力意志控制的“自上而下”效应，首先是孤立的，然后与视野中单个和多个物体的自下而上影响结合起来。本文将介绍一种可视化“注意场”的新方法。(4)在第四组实验中，将使用该方法来验证注意地形可以同时反映视觉显示的空间和物体相关特征的假设。后者将用遮挡、颜色和立体线索进行对象分割测试，以确定诱导的注意地形是否线索不变。(5)基于“注意拥挤”的实验将用于识别注意选择的皮质位点（或多个位点）。(6)在最后的研究中，我们研究了不同空间参照系（视网膜参照系与面向对象参照系）对皮层活动的影响。我们假设枕部视觉区不会受到受试者参照系的影响，但部分顶叶和/或额叶皮质会受到影响。总之，这些研究结果将极大地促进我们对视觉空间注意的神经生理基础和视觉信息进入意识的控制机制的理解。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The long-range goal of this continuing project is to develop and apply the technology of functional magnetic resonance imaging (fMRI) to the study and characterization of neural mechanisms responsible for normal visual perception and attention. The project will concentrate on developing a set of neurophysiological principles that characterize the attention-related control of cortical visual processing in humans. (1,2) In a pair of initial experiments, two fMRI-based measures of cortical activity will be critically evaluated for their ability to accurately reflect the behavioral effects of attention. We will examine the ability of these measures to accurately depict the intensive and topographic properties of attention under three different types of attention-intensive tasks: absolute detection, increment detection and feature conjunction detection. We hypothesize that these measures will reflect the specific attentional demands of the tasks. (3) Next, these measures will be used to observe the "top-down" effects of volitional control of attention, first in isolation, then in conjunction with the bottom-up influences of single and multiple objects in the field of view. A novel method for visualizing the "attentional field" will be introduced. (4) In a fourth set of experiments, this approach will be used to test the hypothesis that attention topography can reflect both spatial and object-related characteristics of the visual display. The latter will be tested with occlusion, color, and stereoscopic cues for object segmentation to determine if the induced attentional topography is cue-invariant. (5) An experiment based on "attentional crowding" will be used to identify the cortical site (or sites) of attentional selection. (6) In a final study, we examine the effects of attending to different spatial reference frames (retinal vs object-oriented) on cortical activity. We hypothesize that occipital visual areas will be unaffected by the subject's reference frame but that portions of parietal and/or frontal cortex will be affected. Together, the results of these studies will significantly advance our understanding of the neurophysiological basis of visuospatial attention and the mechanisms controlling the access of visual information to conscious awareness.