Visual cortex plasticity in blindness: a window into flexibility of human cortex

项目总结 人类大脑皮层的功能弹性有多大？目前的方案通过研究视觉皮质来解决这个问题。 失明的可塑性。对于天生失明的人来说，所谓的“视觉”皮层会对触觉和声音做出反应。 这些新函数与原始的视觉计算有多相似？一个长期的观点是，功能性的 重组是有限的，即使在可塑性的情况下也是如此。然而，我们最近发表的工作和初步数据表明， 盲人视皮层的功能重组可能比之前认为的更加激进。我们 发现视网膜视觉皮层内的区域在语言和数学任务中是活跃的，并且这一活动是 对句子的语法结构和数学公式的难度很敏感。这种功能的重新调整是 鉴于视觉、语言和数学之间的认知和进化差异，这一点令人震惊。这些新的 这一发现为测试人类大脑皮层灵活性的极限提供了前所未有的机会。在本提案中，我们测试 人类大脑皮层功能多能性假说：能够承担广泛的认知功能 取决于投入，其中投入取决于经验和连接性。我们假设与语言相关的 视觉皮质的可塑性是一种更广泛现象的一部分，在失明情况下，视觉皮质被 视觉皮质和高级认知之间的强大连接导致多种截然不同的高级认知功能 网络，特别是额顶网络。到目前为止，几乎没有证据表明 盲人的视觉皮质。Aim 1测试了一项预测，在出生时失明的人中， 视觉皮层内的区域专门化：语言、数字和认知控制，这种专门化是相关的 与不同额顶网络的连通性。在目标2的第一部分中，我们使用了多体素模式分析和 FMRI自适应以测试盲人视皮层代表高级认知信息的预测， 如词义、数量等。接下来，我们测试视觉皮质在功能上 与使用经颅磁刺激(TMS)的高级认知行为相关。《目标3》考察了 视皮层在生命周期中的可塑性。通过与不同年龄失明的人合作，我们测试了 认为皮质只在发育的敏感期具有高级认知功能的假说。这项工作是 与了解视觉障碍的病理生理学和揭示视觉障碍的时间和机制高度相关 失明会影响人类的大脑。从拟议的项目中获得的关于可塑性的见解有 在神经性和认知障碍的背景下，优化皮质功能具有深远的相关性。

PROJECT SUMMARY How functionally flexible is human cortex? The current proposal approaches this question by studying visual cortex plasticity in blindness. In individuals who are blind from birth, so-called “visual” cortices respond to touch and sound. How similar are these new functions to the original visual computations? A longstanding view is that functional reorganization is limited, even in cases of plasticity. Our recent published work and preliminary data, however, suggest that functional reorganization in the visual cortices of blind individuals may be more radical than previously thought. We find that regions within retinotopic visual cortices are active during language and math tasks, and that this activity is sensitive to the grammatical structure of sentences and the difficulty of math equations. Such functional repurposing is striking, in light of the cognitive and evolutionary differences between vision, language and mathematics. These new findings offer an unprecedented opportunity to test the limits of human cortical flexibility. In this proposal we test the hypothesis that human cortex is functionally pluripotent: capable of assuming a wide range of cognitive functions depending on input, where input is determined by experience and connectivity. We hypothesize that language-related plasticity in visual cortices is part of a broader phenomenon whereby, in blindness, visual cortices are colonized by multiple distinct higher-cognitive functions as a result of strong connectivity between visual cortex and higher-cognitive networks, and fronto-parietal networks in particular. Up until now there has been little evidence for specialization within visual cortices of blind individuals. Aim 1 tests the prediction that in individuals who are blind from birth different regions within visual cortices are specialized for: language, number, and cognitive control and that specialization is related to connectivity with different fronto-parietal networks. In the first part of Aim 2, we use multi-voxel pattern analysis and fMRI adaptation to test the prediction that visual cortices of blind individuals represent higher-cognitive information, such as the meanings of words and numerical quantity. Next we test the prediction that visual cortices are functionally relevant to higher-cognitive behavior using transcranial magnetic stimulation (TMS). Aim 3 examines the time-course of visual cortex plasticity during the lifespan. By working with individuals who lost their sight at different ages we test the hypothesis that cortex assumes higher-cognitive functions only during a sensitive period of development. This work is highly relevant to understanding the pathophysiology of visual impairments and uncovering the timing and mechanisms by which blindness affects the human brain. The insights about plasticity to be gained from the proposed project have far-reaching relevance for optimizing cortical function in the context of neurological and cognitive disabilities.