Reorganization of Visual Cortex in Macular Disease

黄斑疾病中视觉皮层的重组

• 批准号: 6983786
• 负责人: NANCY KANWISHER
• 金额: $ 33.68万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-02 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6983786
• 关键词: clinical research; developmental neurobiology; functional magnetic resonance imaging; human subject; macular degeneration; neural degeneration; neural information processing; neural plasticity; neurophysiology; patient oriented research; vision tests; visual cortex; visual fields; visual stimulus

DESCRIPTION (provided by applicant): Macular degeneration (MD)-the loss of central vision due to retinal damage-is the leading cause of visual impairment in the developed world, affecting more than 1.6 million Americans over the age of 50. Individuals with loss of central vision must learn to cope with peripheral vision only, which has low acuity and contrast sensitivity. In normal subjects, a large region of visual cortex is allocated to processing visual information at the center of gaze, and an understanding of what happens to this cortical region when its input is cut off by MD will be critical in any effort to develop better methods of vision rehabilitation. Pilot fMRI data from our lab shows a striking and previously undescribed phenomenon in which the region of visual cortex that responds to the fovea in normal subjects is strongly activated by peripheral stimuli in MD subjects, indicating functional reorganization of retinotopic cortex (FRRC) in MD. The research outlined in this proposal will use fMRI scanning of MD subjects as well normal control subjects while they view visual stimuli, in order to test the following hypotheses about MD: i) that FRRC occurs rapidly after the onset of MD and strengthens over time, such that we will find FRRC in every binocular MD subject who has central field loss, including those who have developed the disease very recently, ii) that FRRC occurs even in monocular MD, although more slowly than in binocular MD, iii) that formerly foveal cortex will respond primarily or only to stimuli presented in the "preferred retinal locus" (i.e. that part of the surviving retina that MD subjects use preferentially for tasks such as reading and face recognition), iv) that FRRC will be found only when the scotomas cover the fovea, not when the fovea is spared and the peripheral visual field is compromised, and v) that formerly foveal cortex contributes to visual performance in MD subjects, but does so for peripheral (rather than central) visual space. This research is important for three reasons: 1) It will inform research into the basic neuroscience of cortical plasticity and its relationship to behavior; 2), It will answer fundamental questions about the neural mechanisms by which MD subjects cope with loss of central vision; 3) It will help guide the search for better rehabilitation strategies for people with MD.

描述（由申请人提供）：黄斑变性（MD）-由于视网膜损伤导致的中心视力丧失-是发达国家视力损害的主要原因，影响超过160万50岁以上的美国人。丧失中央视觉的个体必须学会仅科普周边视觉，其具有低敏锐度和对比敏感度。在正常受试者中，视觉皮层的大区域被分配用于处理凝视中心的视觉信息，并且理解当其输入被MD切断时该皮层区域发生的事情对于开发更好的视觉康复方法的任何努力都至关重要。从我们的实验室的试点功能磁共振成像数据显示了一个惊人的和以前未描述的现象，在该地区的视觉皮层，在正常受试者的中央凹强烈激活的周边刺激在MD的主题，表明功能重组的视网膜皮层（FRRC）在MD。本提案中概述的研究将使用功能磁共振成像扫描MD受试者以及正常对照受试者，当他们看到视觉刺激时，以测试以下关于MD的假设：i）FRRC在MD发作后迅速发生并随时间加强，使得我们将在具有中心场损失的每个双眼MD受试者中发现FRRC，包括最近发展该疾病的那些受试者，ii）FRRC甚至发生在单眼MD中，尽管比双眼MD中更慢，iii）以前的中央凹皮质将主要或仅对“优选视网膜位点”中呈现的刺激作出反应。（即，MD受试者优先用于诸如阅读和面部识别的任务的存活视网膜的那部分），iv）仅当暗点覆盖中央凹时才发现FRRC，而不是当中央凹被保留并且周边视野受损时，以及v）以前中央凹皮质有助于MD受试者的视觉表现，但是对于周边（而不是中央）视觉空间也是如此。这项研究很重要，原因有三：1）它将为皮质可塑性及其与行为关系的基础神经科学研究提供信息; 2）它将回答有关MD受试者科普中心视力丧失的神经机制的基本问题; 3）它将有助于指导MD患者寻找更好的康复策略。