Methods for Dynamic Functional Imaging

描述（由申请人提供）：感知的基本目标是通过解释感官刺激的时间和空间规律来推断世界的结构，这些规律映射到环境中的结构，如物体和表面。本研究的目的是追踪低层次对象处理操作在时间和皮层区域的演变过程中的出现，并研究快速、在线学习或适应如何改变这些反应。我们建议在正常成人中研究视觉系统将视觉场景分割为物体和表面的机制，以及它如何适应具有不同时间规律性水平的刺激的反应，使用脑电图源成像和功能MRI技术的组合。在第一个目标中，我们将研究注意力如何与涉及图像-背景分割的低级机制相互作用。一种新颖的、多输入的刺激和分析方法将被用来分离对图形及其背景的反应。在第二个目标中，我们将通过将行为表现与出现在可预测目标之前的视觉和控制区域的活动相关联，来确定时间可预测性如何塑造行为形状识别的准确性。第二个目标是确定对时间规则刺激作出的预期诱发活动是否可以隐式发生。第三个目标将记录对不同显著程度的可预测和不可预测刺激的反应。预期活动将通过从在一定刺激显著性范围内的时间规则刺激中减去由随机刺激产生的诱发反应的重建来分离。这些数据将用于测试预期活动在前额叶皮层产生的假设，并在枕/枕颞皮层的目标区域产生最大的影响，以降低显著性刺激。我们将研究的任务需要整个视觉层次的综合活动，在前额皮质的执行控制区域和负责感觉运动整合和运动反应的区域。我们开发的将大脑活动和行为联系起来的方法将有助于理解和管理视觉处理、视觉记忆、视觉运动整合和运动执行的障碍。由于这些方法是非侵入性的，它们可以直接应用于临床人群，用于未来对皮质性视觉障碍、创伤性脑损伤、中风、痴呆和先天性脑畸形的研究。这些疾病经常损害视觉处理，并且每一种都经常涉及运动和认知功能的重大损害。仔细修改将在本提案中制定的方案，可能会提供与这些疾病的诊断和管理有关的信息。

DESCRIPTION (provided by applicant): The fundamental goal of perception is to infer the structure of the world through an interpretation of temporal and spatial regularities in sensory stimulation that map onto structures in the environment such as objects and surfaces. The goal of this proposal is to trace the emergence of low-level object processing operations as they evolve in time and cortical area and to study how rapid, on-line learning or adaptation modifies these responses. We propose to study the mechanisms by which the visual system segments the visual scene into objects and surfaces and how it adapts its responses to stimuli with varying levels of temporal regularity using a combination of EEG source-imaging and functional MRI techniques in normal adults. In the first Aim we will study how attention interacts with low-level mechanisms involved in figure-ground segmentation. A novel, multi-input stimulation and analysis method will be used to separate response to figures and their backgrounds. In the second Aim, we will determine how temporal predictability shapes the accuracy behavioral shape discrimination by correlating behavioral performance with activity in visual and control areas that occurs before the presentation of predictable targets. A second goal is to determine if anticipatory evoked activity made in response to temporally regular stimuli can occur implicitly. The third Aim will record responses to predictable and unpredictable stimuli of varying degrees of salience. Anticipatory activity will be isolated by subtracting reconstructions of the evoked response derived from random stimuli from those measured with temporally regular stimuli over a range of stimulus salience. These data will be used to test the hypothesis that anticipatory activity is generated in prefrontal cortex and produces its largest effects in target areas of occipital/occipital temporal cortex for low salience stimuli. PUBLIC HEALTH RELEVANCE The tasks we will study require integrated activity throughout the visual hierarchy, in executive control areas of pre-frontal cortex and in areas responsible for sensory motor integration and motor response. The methods we develop to link brain activity and behavior at each of these levels will be relevant to understanding and managing disorders of visual processing, visual memory, visuo-motor integration and motor execution. Because the methods are non-invasive they can be applied directly to clinical populations in future studies of Cortical Visual Impairment, traumatic brain injury, stroke, dementia and congenital brain malformations. These disorders frequently compromise visual processing and each often involves significant compromise of motor and cognitive functions. Careful adaptation of the protocols that will be developed in this proposal may provide information relevant to the diagnosis and management of these disorders.