Reversing Hemianopia with Cross-Modal Training

项目摘要 中脑上级丘（SC）通常需要同侧视觉皮层的影响来发挥其关键作用。 对侧线索产生视觉反应的作用。因此，视觉皮层损伤消除了 正常的视觉特征处理和同侧SC的视觉功能。结果是对侧 偏盲尽管来自动物模型的见解表明，通过 尽管有许多干预措施，但这些都没有为人类患者提供可行的治疗选择。然而，使用 动物模型，我们最近已经证明，一个非侵入性的康复训练模式（使用 视觉线索）可以永久地恢复动物的视力， 视觉皮层的所有相邻区域。不幸的是，我们在很大程度上忽视了神经变化， 这种视觉的恢复。尽管如此，我们的初步数据确实表明，跨通道训练 皮质-SC回路中的功能重组涉及联合皮质的特定区域（即，的 前外侧裂沟（AES）。这些适应性变化使SC神经元再次具有视觉功能。 反应和支持视觉行为的同侧视觉皮层的情况下-大概通过 来自AES的补偿输入。我们的目标是使用生理和行为技术， 评估大的视觉皮层病变对AES中神经元特性的生理后果 和偏盲动物的SC，并确定它们的特性如何通过交叉模式训练进行修改， 这种视觉恢复了。我们的首要假设是，通过赫布机制，跨模态训练是 能够放大从视觉皮层以外的来源输入到这些区域的正常阈下输入。 了解如何通过非手术的行为训练来利用这种回路的固有可塑性 改善偏侧神经的技术将帮助我们了解该系统的潜在功能， 并提供宝贵的见解，以促进战略，处理这种衰弱的条件，在人类 患者

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.