The Effects of Visual Deprivation

描述（由申请人提供）：最近开发的外科手术，角膜缘干细胞置换术，现在允许许多以前不适合手术的患者进行角膜置换。这些患者中的许多人遭受了长期的视觉剥夺，因此提供了一个极其难得的机会来检查视觉功能是如何依赖于经验的。我们将研究：（1）基于剥夺的敏锐度丧失的神经部位。我们将分区的网站剥夺为基础的分辨率损失之间的光学，外侧膝状体核，初级和次级视觉区，使用结合的心理物理（外部）对比敏感度功能，干涉对比敏感度功能和神经反应功能内的外侧膝状体核，纹状体，和纹外视觉区使用功能性磁共振成像（fMRI）测量。(2)行为丧失作为剥夺的功能。初步数据表明，长期的视觉剥夺也会导致更高层次的视觉过程的缺陷，例如对图形、物体和面孔的处理。相比之下，颜色和运动处理似乎相对不受长期剥夺的影响。我们将对患者进行广泛的行为任务测试，以了解剥夺的影响如何与任务相互作用。(3)行为缺失的神经部位。我们将根据解剖学和功能标准定义广泛的皮质视觉区，包括外侧膝状体核、V1-V4区、运动区MT+和梭状舌回中被认为负责面部和物体处理的区域。我们将比较患者的行为表现与这些视觉区域的大小和敏感度。除了是研究剥夺对人类视觉系统影响的独特机会外，这项研究还应该为正在接受视力恢复手术的患者提供有关术后他们应该期待什么样的视力的信息。干细胞置换是一种越来越普遍的主要手术，近年来，视网膜假体等其他视力恢复技术也取得了显著进展。重要的是，患者在选择接受视力恢复手术时，要准确估计风险和收益。

DESCRIPTION (provided by applicant): A recently developed surgical procedure, limbal stem cell replacement, now permits corneal replacement in many patients who were previously ineligible for surgery. Many of these patients have suffered long-term visual deprivation, thus providing an extremely rare opportunity to examine how visual function is dependent on experience. We will study: (1) The neural site of deprivation-based acuity loss. We will partition the sites of deprivation-based resolution loss between the optics, lateral geniculate nucleus, and primary and secondary visual areas, using a conjunction of the psychophysical (external) contrast sensitivity function, the interferometric contrast sensitivity function and the neural response function within the lateral geniculate nucleus, striate, and extrastriate visual areas measured using functional magnetic resonance imaging (fMRI). (2) Behavioral losses as a function of deprivation. Preliminary data suggests that long-term visual deprivation also results in deficits in higher-level visual processes, such as the processing of configural form, objects, and faces. In contrast, color and motion processing seems relatively unaffected by long periods of deprivation. We will test our patients on a wide range of behavioral tasks to see how the effects of deprivation interact with task. (3) The neural site of behavioral losses. We will define, based on both anatomical and functional criteria, a wide range of cortical visual areas, including the lateral geniculate nucleus, areas V1-V4, motion area MT+ and regions in the fusiform lingual gyd thought to be responsible for face and object processing. We will compare patients' behavioral performance to the size and sensitivity of these visual areas. Besides being a unique opportunity to study the effects of deprivation on the human visual system, this research should provide patients who are undergoing sight recovery procedures with information as to what sort of sight they should expect postoperatively. Stem cell replacement is a major operation that is becoming more and more common, and other techniques for sight restoration, such as retinal prostheses, have shown remarkable progress in recent years. It is important that patients are given an accurate estimation of risks and benefits when being given the option of undergoing sight-recovery procedures.