Plasticity of Orthographic and Semantic Representations in the Human Brain

人脑中的拼写和语义表示的可塑性

• 批准号: 1026934
• 负责人: Maximilian Riesenhuber
• 金额: $ 65.07万
• 依托单位: Georgetown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1026934&HistoricalAwards=false
• 关键词: Plasticity; Orthographic; Semantic; Representations; Human

The assignment of meaning to sensory stimuli lies at the foundation of human cognition. Reading written words is an excellent domain through which to study the neural bases of this cognitive process. With support from the National Science Foundation, Maximilian Riesenhuber, Ph.D., of Georgetown University, is integrating behavioral approaches with advanced brain imaging techniques to learn the answer to fundamental questions about how the brain processes written words and learns their meaning. Given the cultural recency of reading and the variability of lexica across languages, reading necessarily depends on specific neural representations that are acquired through experience with written words. For example, the written word 'apple' must be connected to semantic concept information learned previously, from seeing or tasting an actual apple. The underlying neural mechanisms that support the learning of orthographic and semantic information and their integration with perceptual learning are still poorly understood. While researchers have identified an area in the left half of the brain, the so-called 'visual word form area,' that appears to be crucial to reading, scientists debate the precise role of this area: Does it contain a collection of word fragments, a dictionary or an encyclopedia? Are the meanings of words and objects stored together in sensory cortex, or are they linked in higher cognitive areas? How does the brain learn that a particular word refers to a particular concept? How does the brain connect orthographic knowledge, learned in the left half of the brain, to perceptual information that has been shown to be predominantly represented in the right half? Resolving these questions is of key interest for cognitive models of reading and the broader understanding of how the brain makes sense of the world. The project builds on Riesenhuber's previous experimental and computational research on general object recognition and learning and recent results showing that the human brain contains a visual word dictionary in the 'visual word form area.' The first study is examining how learning new words refines the brain's visual word representation. The second is examining how novel words are linked to meaning in the brain, testing the hypothesis that the visual word dictionary contains only orthographic information, and that the meanings of words are stored in other brain areas. The third is investigating how orthographic, semantic, and perceptual information are integrated; and how the two brain hemispheres cooperate in linking pictures of objects to verbal labels. The project not only increases the understanding of normal visual word recognition, and how the brain learns to represent objects and associate semantic meaning; but it also provides a framework that can be used to study topics such as reading acquisition, second language learning, and disordered reading. In addition, the techniques developed for this line of research can be translated to study the neural representation of different writing systems, specifically logographic scripts such as Chinese, and the integration of perceptual and semantic information in sign language. The research project is leveraged extensively to train the next generation of scientists, at the high school, undergraduate, and graduate levels. The project includes a summer outreach program, emphasizing the involvement of underrepresented groups through a partnership with Howard University in Washington, DC. In addition, the project presents opportunities for high school students with an interest in cognitive neuroscience to gain hands-on research experience, through a partnership with Thomas Jefferson High School for Science and Technology in Alexandria, VA.

感官刺激的意义分配是人类认知的基础。阅读书面文字是研究这一认知过程的神经基础的绝佳领域。在国家科学基金会的支持下，乔治城大学的Maximilian Riesenhuber博士正在将行为方法与先进的脑成像技术相结合，以了解大脑如何处理书面文字并学习其含义等基本问题的答案。鉴于阅读的文化近代性和不同语言之间词汇的可变性，阅读必然依赖于特定的神经表征，这些表征是通过书面文字的经验获得的。例如，书写单词“苹果”必须与之前从看到或品尝实际的苹果中学到的语义概念信息联系起来。支持正字法和语义信息学习及其与知觉学习整合的潜在神经机制仍然知之甚少。虽然研究人员已经在大脑的左半部分发现了一个区域，即所谓的“视觉词汇形成区”，它似乎对阅读至关重要，但科学家们对这个区域的确切作用仍存在争议：它是包含单词片段的集合、词典还是百科全书？单词和物体的含义是存储在感觉皮层中，还是在更高的认知区域中联系在一起？大脑是如何知道一个特定的词指的是一个特定的概念？大脑是如何将在左脑学习的正字法知识与在右脑主要表现的知觉信息联系起来的？解决这些问题对于阅读的认知模型和对大脑如何理解世界的更广泛理解至关重要。该项目建立在Riesenhuber之前对一般物体识别和学习的实验和计算研究的基础上，最近的结果表明，人类大脑在“视觉单词形式区域”中包含一个视觉单词字典。第一项研究是研究学习新单词如何改善大脑的视觉单词表征。第二个是研究新单词在大脑中是如何与意思联系起来的，测试视觉单词词典只包含正字法信息，单词的意思存储在大脑其他区域的假设。第三是研究如何整合正字法、语义和感知信息；以及两个大脑半球如何合作将物体图片与语言标签联系起来。该项目不仅增加了对正常视觉单词识别的理解，以及大脑如何学习表征物体和联想语义；但它也提供了一个框架，可用于研究主题，如阅读习得，第二语言学习和无序阅读。此外，为这一研究方向开发的技术可以翻译为研究不同书写系统的神经表征，特别是像汉语这样的符号文字，以及手语中感知和语义信息的整合。该研究项目被广泛用于培养高中、本科和研究生阶段的下一代科学家。该项目包括一个夏季外展项目，通过与华盛顿特区霍华德大学的合作，强调弱势群体的参与。此外，该项目还为对认知神经科学感兴趣的高中生提供了机会，通过与弗吉尼亚州亚历山大市托马斯杰斐逊科技高中的合作，获得实践研究经验。