FUNCTIONAL MAPPING OF HUMAN VISUAL CORTEX

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。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，以表征人类大脑皮层视觉处理的注意力相关控制。(1，2)在两个初步实验中，将对两个基于fMRI的皮质活动指标进行批判性评估，以确定它们是否能够准确反映注意力的行为影响。我们将考察这些测量在三种不同类型的注意密集型任务：绝对检测、增量检测和特征关联检测下准确刻画注意力的集约性和地形性的能力。我们假设这些措施将反映任务的具体注意要求。(3)接下来，这些测量将被用来观察注意意志控制的自上而下效应，首先是孤立的，然后是结合视场中单个和多个物体的自下而上的影响。我们将介绍一种新的可视化“注意领域”的方法。(4)在第四组实验中，这一方法将被用来检验注意地形图能够反映视觉显示的空间特征和对象相关特征的假设。后者将用遮挡、颜色和立体线索进行对象分割的测试，以确定诱导的注意地形图是否线索不变。(5)基于“注意拥挤”的实验将被用来识别注意选择的一个或多个大脑皮层部位。(6)在最后一项研究中，我们考察了关注不同空间参照系(视网膜与面向对象)对皮质活动的影响。我们假设，枕叶视觉区域不会受到受试者参照系的影响，但顶叶和/或额叶皮质的部分会受到影响。综上所述，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学基础以及控制视觉信息进入意识意识的机制的理解。

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.