Neural dynamics of speech encoding and maintenance during phonological working memory

项目摘要 语音工作记忆是维持和操纵言语表征的能力 在工作记忆中暂时出现的声音它被认为在语言的许多方面起着关键作用 发展，如词汇学习，句子处理和识字技能的获得，以及缺陷 语音工作记忆是许多发展性语言障碍的诊断。经典 语音工作记忆的理论框架认为，信息是在一个专门的工作 记忆存储缓冲区，与语音感知皮层分离;尽管最近的认知模型倾向于 一种观点认为，负责感知语音信息的同一皮层基底也 支持在工作记忆延迟期间维持这些神经表征。事实上，最近的人类 神经影像学研究表明语音工作记忆依赖于语音感知的恢复， 在各种任务中，特别是左上级颞回的激活， 与语音工作记忆临床评估的扫描仪外表现相关。然而，在这方面， 因为这些研究不能在时间上区分语音编码过程中的激活和 编码后持续保持语音表征，我们不知道这些 过程归因于观察到的与行为的相关性。因此， 这些发现，以及他们的临床解释，关键取决于解决语音编码， 工作记忆在时间和空间上的维持过程。我们建议调查的神经动力学 语音工作记忆使用颅内皮层电图，它允许同时 通过放置电极，以毫米和毫秒分辨率记录许多离散的神经群体 直接在清醒的大脑皮层表面，行为人类患者接受手术， 难治性癫痫这项技术将使我们能够直接观察言语之间的关系， 语音工作记忆的编码和维持。通过三个具体目标，我们将（1） 确定在语音工作记忆过程中大脑皮层神经激活的时间过程，（2） 确定在编码期间表示音位信息的相同感知系统是否也 在工作记忆中积极维持这些表征，以及（3）确定感知语音是否 系统在工作存储器维护期间参与更广泛的网络级动态。通过实现 这些目标，这个项目将促进我们的作用感知语音系统的理解，在 语音工作记忆最终，这些发现可以用来为角色提供理论基础 语音工作记忆在语言发展中的作用，并对临床特征有影响 和语音工作记忆缺陷的补救。

PROJECT SUMMARY Phonological working memory is the capacity to maintain and manipulate representations of speech sounds temporarily in working memory. It is believed to play a critical role in many aspects of language development, such as vocabulary learning, sentence processing, and acquisition of literacy skills, and deficits of phonological working memory are diagnostic of many developmental language disorders. The classic theoretical framework for phonological working memory posits that information is held in a dedicated working memory storage buffer, separate from speech perception cortex; although more recent cognitive models favor a view in which the same cortical substrate responsible for perception of phonological information also supports maintenance of those neural representations during working memory delay. Indeed, recent human neuroimaging studies show phonological working memory load-dependent recruitment of speech-perception cortex during a variety of tasks and in particular, activation in left superior temporal gyrus has been shown to correlate with out-of-scanner performance on clinical assessments of phonological working memory. However, because these studies are not able to temporally distinguish activation during phonological encoding from persistent maintenance of phonological representations after encoding, we do not know which of these processes to attribute to the observed correlations with behavior. Therefore, the theoretical implications of these findings, as well as their clinical interpretations, critically depend on resolving phonological encoding and working memory maintenance processes in time and space. We propose to investigate the neural dynamics of phonological working memory using intracranial electrocorticography, which allows for the simultaneous recording of many discrete neural populations with millimeter- and millisecond-resolution by placing electrodes directly on the cortical surface of the brains of awake, behaving human patients undergoing surgery for medically intractable epilepsy. This technique will allow us to observe directly the relationship between speech encoding and maintenance during phonological working memory. Through three specific aims we will (1) determine the time course of neural activation during phonological working memory across the cortex, (2) determine whether the same perceptual systems that represent phonological information during encoding also actively maintain those representations during working memory, and (3) determine whether perceptual speech systems participate in broader network-level dynamics during working memory maintenance. By achieving these aims, this project will advance our understanding of the role perceptual speech systems play during phonological working memory. Ultimately, such findings can be used to inform the theoretical basis for the role of phonological working memory in language development and has implications for the clinical characterization and remediation of phonological working memory deficits.