Reorganization of Visual Cortex in Macular Disease

黄斑疾病中视觉皮层的重组

• 批准号: 7273523
• 负责人: NANCY KANWISHER
• 金额: $ 36.43万
• 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/7273523
• 关键词: Accommodation phosphene; Accounting; Adult; Affect; Age; Age of Onset; American; Behavior; Behavioral; Bilateral; Blindness; Characteristics; Clinical; Condition; Contrast Sensitivity; Data; Detection; Development; Disease; Employee Strikes; Face; Functional Magnetic Resonance Imaging; Individual; Learning; Location; Macular degeneration; Maps; Methods; Neurosciences; Performance; Peripheral; Play; Process; Psychophysiology; Reading; Rehabilitation therapy; Research; Residual state; Retina; Retinal; Retinitis Pigmentosa; Role; Running; Scanning; Scotoma; Severities; Signal Transduction; Stimulus; Testing; Thalamic structure; Time; Transcranial magnetic stimulation; Vision; Visual; Visual Cortex; Visual Fields; Visual impairment; coping; disorder of macula of retina; fovea centralis; gaze; macula; monocular; neuromechanism; rehabilitation strategy; remediation; research study; retinal damage; retinotopic; visual information; visual performance; 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(申请人提供)：黄斑变性(MD)--由于视网膜损伤而导致的中心视力丧失--是发达国家视力受损的主要原因，影响超过160万50岁以上的美国人。中心视力丧失的人必须学会只处理周边视力，因为周边视力和对比敏感度较低。在正常受试者中，视觉皮质的一大块区域被分配用于处理凝视中心的视觉信息，了解当MD切断输入时这一皮质区域发生了什么，这对于开发更好的视力康复方法至关重要。来自我们实验室的飞行员fMRI数据显示了一个以前没有描述过的显著现象，在正常受试者中，对中心凹做出反应的视觉皮质区域在MD受试者中被外周刺激强烈激活，这表明MD患者的视网膜皮质(FRRC)进行了功能重组。在该提案中概述的研究将使用MD受试者和正常对照组受试者在观看视觉刺激时的fMRI扫描，以检验关于MD的以下假设：i)FRRC在MD开始之后迅速发生并随时间增强，使得我们将在每个具有中心视野损失的双眼MD受试者中发现FRRC，包括那些最近发展为疾病的受试者，ii)FRRC甚至在单眼MD中发生，尽管比双眼MD更慢，Iii)以前的中心凹皮质主要或仅对“首选视网膜区域”(即MD受试者优先用于阅读和人脸识别等任务的存活视网膜的那一部分)中的刺激做出反应；iv)只有当暗点覆盖中心凹时，才会发现FRRC，而不是当中心凹被保留和外围视野受损时；v)以前的中心凹皮质对MD受试者的视觉表现有贡献，但对外围(而不是中央)视觉空间起作用。这项研究之所以重要，有三个原因：1)它将为皮质可塑性的基础神经科学及其与行为的关系的研究提供信息；2)它将回答关于MD受试者应对中央视力丧失的神经机制的基本问题；3)它将有助于指导为MD患者寻找更好的康复策略。