Reversing Hemianopia with Cross-Modal Training

项目摘要 中脑上丘(SC)通常需要同侧视觉皮质的影响才能发挥其关键作用。 在产生对侧提示的视觉运动反应中的作用。因此，视觉皮质损伤消除了这两种情况 正常的视觉特征加工和同侧SC的视觉功能。结果是产生了一个对侧 偏盲。尽管来自动物模型的洞察力表明这种缺陷的改善是有可能通过 尽管有许多干预措施，但这些措施都不能为人类患者提供可行的治疗选择。但是，使用 动物模型，我们最近证明了一种非侵入性康复训练范例(使用 听觉-视觉提示)可以永久性地恢复偏盲动物的视力 视觉皮质的所有毗连区域。不幸的是，我们在很大程度上忽视了导致神经变化的因素 这种视力的恢复。然而，我们的初步数据确实表明，跨模式培训产生了 皮质-SC环路中的一种功能重组，涉及联合皮质的特定区域(即 外胚层前沟(AES)。这些适应性变化使SC神经元再次具有视觉能力 在没有同侧视皮层的情况下的反应和支持视觉行为--推测是通过 来自AES的补偿性输入。我们的目标是使用生理和行为技术 在AES中评估大视皮层损伤对神经元特性的生理影响 和偏盲动物的SC，并确定它们的特性是如何通过跨模式训练而改变的 这一愿景得到了恢复。我们最重要的假设是，通过Hebbian机制进行的跨模式培训 能够放大来自视觉皮质以外的来源对这些区域的正常亚阈值输入。 了解如何通过非手术的行为训练来利用这一回路的固有可塑性 改善半身不遂的技术将帮助我们理解这个系统的潜在功能能力， 并提供了宝贵的见解，以促进应对这种人类虚弱状况的策略 病人。

Project Summary The midbrain superior colliculus (SC) typically requires influence from ipsilateral visual cortex to play its critical role in generating visuomotor responses to contralateral cues. Thus, visual cortex lesions eliminate both normal visual feature processing and the visual functions of the ipsilateral SC. The result is a contralateral hemianopia. Although insights from animal models suggest amelioration of this deficit is possible through a number of interventions, none of these offers viable therapeutic options for human patients. However, using an animal model, we have recently demonstrated that a non-invasive rehabilitative training paradigm (using auditory-visual cues) can permanently reinstate vision in animals rendered hemianopic by unilateral removal of all contiguous areas of visual cortex. Unfortunately, we are largely ignorant of the neural changes that induce this reinstatement of vision. Nevertheless, our preliminary data do suggest that cross-modal training produces a functional reorganization in a cortico-SC circuit that involves specific regions of association cortex (i.e., the anterior ectosylvian sulcus, AES). These adaptive changes render SC neurons once again capable of visual responses and of supporting visual behavior in the absence of ipsilateral visual cortex – presumably via compensatory inputs from AES. Our objective here is to use physiological and behavioral techniques to evaluate the physiological consequences of large visual cortex lesions on the neuronal properties in the AES and SC of hemianopic animals, and to determine how their properties are modified by cross-modal training so that vision is restored. Our overarching hypothesis is that cross-modal training, via Hebbian mechanisms, is able to amplify the normally subthreshold inputs to these regions from sources other than visual cortex. Understanding how the inherent plasticity of this circuit can be harnessed via non-surgical, behavioral training techniques to ameliorate hemineglect will help us understand the latent functional capabilities of this system, and provide invaluable insights to facilitate strategies for dealing with this debilitating condition in human patients.