Architecture and plasticity of auditory lexical representations in the human brain

考虑到全球语言的多样性和丰富性，言语感知可以说是人类大脑的主要成就之一。虽然认知神经学家现在广泛支持皮质区域层次结构服从于听觉和语音处理的概念，但对于不同大脑区域在语音识别中所起的作用，语音系统如何学习和代表口语单词，以及通过一种感觉(例如，通过阅读)学习单词如何允许大脑通过另一种感觉(例如，通过听力)识别相同的单词，存在着很大的分歧。在国家科学基金会的支持下，我们将使用先进的功能磁共振成像(FMRI)来研究这些问题。具体地说，该项目旨在通过首次将功能磁共振技术应用于这一领域，解决正在进行的关于单词在大脑中如何以及在哪里表示的重大争议，这些技术已成功地用于回答书面单词领域的相关问题。第二项研究将探索大脑如何学习新的口语单词，并将它们添加到听觉词典中。在最后一组研究中，该项目将为我们理解阅读中听觉和视觉系统是如何联系的，以及这种相互作用是如何通过跨感官学习实现的，开辟了新的天地。理解语音处理和语言的跨感觉学习的神经基础不仅是基础科学非常感兴趣的领域，而且也是从教育和语言学习到工程(通过阐明深层多感觉层次的有效学习算法，例如用于自动语音识别)以及生物医学领域(通过为研究包括阅读困难和语言理解障碍在内的一系列疾病建立基础)的其他领域。该研究项目将形成一个培养下一代科学家的机会，包括研究生、本科生和高中。更科学地说，该项目的首要目标是研究人脑中听觉词汇的存在和可塑性，并了解书面和听觉语音表征的耦合，从而实现词汇学习的跨模式迁移。该项目有三个目标：目标1解决目前关于听觉单词表征在大脑中的存在和位置的争议。为了识别“视觉词形区域”中的“视觉词汇”，我们将使用敏感的fMRI快速适应(fMRI-RA)和其他先进的fMRI技术来检验在左侧前上颞叶皮质类似的“听觉词形区域”内存在(接受性)听觉词汇的假说。同时，我们将测试在听觉背向流的运动相关言语区域中是否存在另一个词汇，这些词汇代表发音形式，这些发音形式是由言语知觉通过“反向模型”自动激活的。目的2旨在探讨在听觉词汇中加入新词所引起的可塑性。目的3研究书面语言与听觉系统的相互作用。先前的研究表明，阅读激活了熟练读者的语音表征，而这种语音编码对阅读习得至关重要。我们将测试新的假设，即书写的单词会导致听觉系统的广泛激活，以及对新书写的单词的训练可以驱动听觉词汇系统中的单词选择性重新连接。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Considering the diversity and richness of languages spoken around the globe, speech perception is arguably one of the main achievements of the human brain. While there is now broad support among cognitive neuroscientists for the concept of a hierarchy of cortical areas subserving auditory and speech processing, there is substantial disagreement about the roles different brain areas play in speech recognition, how the speech system learns and represents spoken words, and how learning words through one sense (e.g., through reading) can allow the brain to recognize the same words through another sense (e.g., through hearing). With support from the National Science Foundation, we will use advanced functional magnetic resonance imaging (fMRI) to investigate these questions. Specifically, the project is designed to resolve a major ongoing controversy regarding how and where words are represented in the brain by, for the first time, applying fMRI techniques to this field that have been used successfully to answer related questions in the domain of written words. A second study will probe how the brain learns new spoken words and adds them to the auditory lexicon. In the final set of studies, the project will break new ground in our understanding of how the auditory and visual systems are linked in reading, and how this interaction is enabled by cross-sensory learning. Understanding the neural bases of speech processing and cross-sensory learning of language are areas of great interest not only for basic science but also other areas ranging from education and language learning to engineering (by elucidating effective learning algorithms for deep multisensory hierarchies, e.g., for automatic speech recognition) as well as biomedical fields (by building a foundation to study a range of disorders, including dyslexia and language comprehension deficits). The research project will form an opportunity to train the next generation of scientists, at the graduate, undergraduate, and high school levels. In more scientific detail, the overarching goal of the proposed project is to study the existence and plasticity of auditory lexica in the human brain, and to understand coupling of written and auditory speech representations that permit cross-modal transfer of lexical learning. The project has three Aims: Aim 1 addresses the current controversy regarding the existence and location of auditory word representations in the brain. Translating techniques we previously developed to identify a "visual lexicon" in the "Visual Word Form Area", we will use sensitive fMRI rapid adaptation (fMRI-RA) and other advanced fMRI techniques to test the hypothesis of a (receptive) auditory lexicon within an analogous "Auditory Word Form Area" in left anterior superior temporal cortex. At the same time, we will test whether another lexicon exists in motor-related speech areas of the auditory dorsal stream representing articulatory word forms that are automatically activated by speech perception via an "inverse model". Aim 2 is designed to probe the plasticity invoked by the addition of novel words to the auditory lexicon. Aim 3 studies the interaction of written language with the auditory system. Prior studies have shown that reading activates phonological representations in proficient readers, and that this phonological recoding is crucial for reading acquisition. We will test the novel hypothesis that written words cause widespread activation of the auditory system and that training on novel written words can drive word-selective rewiring in the auditory lexical system.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.