The Effects of Visual Deprivation

描述(申请人提供)：最近开发的一种外科手术，角膜缘干细胞置换，现在允许许多以前不符合手术条件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研究视觉功能是如何依赖经验的。我们将研究：(1)基于剥夺的视力丧失的神经部位。我们将结合心理物理(外部)对比敏感度函数、干涉对比敏感度函数和功能磁共振成像(FMRI)测量的外侧膝状体、纹状体和纹状体外视区内的神经反应函数，将基于剥夺的分辨率丧失的部位划分在光学、外侧膝状体核以及初级和次级视觉区域之间。(2)作为剥夺功能的行为损失。初步数据表明，长期的视觉剥夺还会导致高级视觉过程的缺陷，如对形态、物体和面孔的加工。相比之下，颜色和动作加工似乎相对不受长期剥夺的影响。我们将在广泛的行为任务中测试我们的患者，看看剥夺的影响如何与任务相互作用。(3)行为损失的神经部位。我们将根据解剖学和功能标准定义广泛的皮质视觉区域，包括外侧膝状核、V1-V4区、运动区MT+和梭形舌回中被认为负责面部和物体加工的区域。我们会将患者的行为表现与这些视觉区域的大小和敏感度进行比较。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程序的患者提供信息，告诉他们手术后应该看到什么样的视力。干细胞置换是一项越来越常见的重大手术，其他恢复视力的技术，如视网膜假体，近年来也显示出显著的进步。重要的是，当患者可以选择接受视力恢复手术时，必须准确地估计风险和收益。

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.