Developing a rational strategy for visual rehabilitation after cortical lesions

视野丧失是中风的常见必然结果（Pollock等人，The科克伦图书馆：John Wiley&Sons; 2011，第103页）。 p. 1-83），这是普遍存在的VA人群。大脑中动脉和后动脉梗塞常损害视力 导致部分或完全同侧偏盲或象限盲的皮质网络。最 常见的临床上显著的视皮层损伤涉及初级视皮层和邻近区域（区域 V1+）。V1区是视觉输入到更高（纹外）皮质区的主要中继，V1区的损伤会导致 对侧暗点，在暗点内视觉感知严重受损。由此造成的视觉缺陷是 长期以来被认为难以康复，即基本上不可逆转，并损害生活质量 显著视野丧失损害了许多日常生活活动，包括安全行走、驾驶， 阅读、烹饪、监督未成年人和其他人，明显降低了病人的独立性（退伍军人健康 2002年倡议：视力障碍和失明）。视觉运动感知的丧失对于以下患者是特别成问题的： 导航环境和避免与移动物体碰撞。在这里我们重点研究 视觉运动知觉的康复。 几项研究表明，视觉皮层可以从暗点的内部驱动，即从 没有视觉感知的视野。一个这样的区域，可以在视觉上调节， 缺乏V1输入的是hV 5/MT+，这是一个对视觉运动感知很重要的区域。虽然这种调制是 弱，一般不赋予有用的视力（“盲视”），它提出了希望，适当的设计， 新的康复战略也许能够加强这些部分发挥作用的途径，促进康复。 最近的工作（Huxlin等人，J Neuroscience 29（13）：3981-91，2009）已经表明，视觉神经系统中的强化训练可以改善视觉神经系统的功能。 运动辨别任务可以改善某些皮层V1损伤受试者的视觉运动感知（参见 图5-6）。然而，这项工作仍处于初步阶段。具体而言，并非所有受试者都受益于 （第C2节），不清楚视野的哪些部分适合视力康复， 恢复机制尚不清楚。我们的目标有两个：1）引导功能性磁共振 本发明涉及用于识别视觉区域的功能磁共振成像（fMRI）群体感受野映射方法， 在初级视皮层（V1+区）损伤后更容易进行视觉康复。2)探测 最近报道的康复诱导的视觉表现改善的潜在机制， 发生在某些受试者中（初步数据图5-7）。我们将致力于实现以下具体目标： 目的1：我们将证明功能性磁共振成像（fMRI）群体感受野映射 方法可以识别更适合视觉运动感知康复的视野区域 在初级视觉皮层（V1+区）损伤后。假设1：暗点的区域， 在备用区V1和hV 5/MT+（见图1）的驱动fMRI活动将更容易恢复，并将达到 与仅激活hV 5/MT+区域的区域相比，更高的行为阈值。 目的2：研究早期视区、hV 5/MT+和额-颞叶视区的视觉调制强度如何变化。 顶叶网络辅助注意力和高阶视觉处理，康复训练后。 确定观察到的变化是否与恢复相关。假设2：培训将增加 视觉运动刺激反应的信噪比在hV 5/MT+区，而在备用V1+区 而早期的纹外区将保持相对不变。hV 5/MT+应答强度的增加将 最好与恢复相关。hV 5/MT+应答强度的变化可能通过自上而下介导 通路，可能与注意力网络有关（见[43] [44]和初步数据图5-7）。 我们的长期目标是利用从功能磁共振成像方法获得的信息来实现一个原则性的策略， 开发视觉皮层损伤后的康复治疗。

Visual field loss is a common corollary of stroke (Pollock et al,The Cochrane Library:John Wiley & Sons; 2011,p p. 1-83) that is prevalent in the VA population. Posterior and middle cerebral artery infarcts often injure visual cortical networks resulting in partial or complete homonymous hemianopia or quadrantanopia. The most common clinically significant visual cortical injury involves the primary visual cortex and adjacent regions (area V1+). Area V1 is the chief relay of visual input to higher (extrastriate) cortical areas, and V1 lesions result in a dense contralateral scotoma within which visual perception is severely impaired. The resulting visual deficit is long thought to be resistant to rehabilitation, i.e. to be essentially irreversible, and impairs quality of life significantly. Visual field loss impairs many activities of daily living, including the ability to ambulate safely, drive, read, cook, supervise minors, and others, markedly reducing the independence of the patient (Veterans Health Initiative 2002: Visual Impairment and Blindness). Loss of visual motion perception is particularly problematic for navigating the environment and for avoiding collision with moving objects. Here we focus on studying rehabilitation of visual motion perception. Several studies demonstrated that visual cortex can be driven from the interior of the scotoma, i.e. from areas of the visual field where there is no visual perception. One such area that can be visually modulated in the absence of V1 input is hV5/MT+, an area important for visual motion perception. Although this modulation is weak and does not generally confer useful vision (“blindsight”), it raises the hope that appropriately designed new rehabilitative strategies may be able to strengthen these partially functioning pathways promoting recovery. Recent work (Huxlin et al. J Neuroscience 29(13):3981-91, 2009) has shown that intensive training in a visual motion discrimination task can improve visual motion perception in some subjects with cortical V1 lesions (see fig 5-6). However, this work is still at the preliminary stage. Specifically, not all subjects appear to benefit (section C2), it is not clear which parts of the visual field are amenable to visual rehabilitation, and the mechanism of recovery remains unclear. Our goal here is twofold: 1) To pilot functional magnetic resonance imaging (fMRI) population receptive field mapping methods for identifying regions of the visual field that are more amenable to visual rehabilitation after lesions of the primary visual cortex (area V1+). 2) To probe the mechanisms underlying the recently reported rehabilitation-induced improvement in visual performance that occurs in some subjects (preliminary data fig. 5-7). We will address the following specific aims: Aim 1: We will show that functional magnetic resonance imaging (fMRI) population receptive field mapping methods can identify regions of the visual field that are more amenable to visual motion perception rehabilitation after lesions of the primary visual cortex (area V1+). Hypothesis 1: Regions of the scotoma that elicit visually driven fMRI activity in both spared area V1 and hV5/MT+ (see fig.1) will be easier to rehabilitate, and will reach higher behavioral thresholds, compared to regions that activate only area hV5/MT+. Aim 2: Study how the strength of visual modulation changes in early visual areas, in hV5/MT+, and in fronto- parietal networks subserving attention & higher-order visual processing, following rehabilitative training. Determine whether observed changes are correlated with recovery. Hypothesis 2: Training will increase the signal to noise ratio of the response to visual motion stimuli in area hV5/MT+, while responses in spared V1+ and early extrastriate areas will remain relatively unchanged. Increase in hV5/MT+ response strength will correlate best with recovery. The change in hV5/MT+ response strength will likely be mediated via top down pathways, potentially associated with attentional networks (see [43] [44] and preliminary data fig. 5-7). Our long-term goal is to use information obtained from fMRI methods to implement a principled strategy for developing rehabilitative treatments following visual cortex injury.