Neural Dynamics of Spoken Word Recognition

描述（由申请人提供）：大脑和认知科学的研究提供了压倒性的证据，证明即使是看似简单的任务，如理解口语，也依赖于各种不同类型的信息（如听觉、语音、语音、词汇、语义等）的相互作用。这些相互作用是值得注意的，因为它们似乎允许听者，包括许多负责代表这些类型信息的大脑区域局灶性损伤的中风患者，识别口语，即使由于发音不清，语音合成不完美，嘈杂的环境或由于数字减少或过滤而导致的语音不清晰（例如通过人工耳蜗，助听器或电话连接不良）。由于当前行为和单模成像范式的可解释性存在内在局限性，关于许多这些相互作用的性质或必要性仍然存在激烈的争论。本研究通过整合MRI、MEG和EEG数据来提供语音感知任务中大脑活动的高时空分辨率图像，从而解决了这些局限性。这些数据将提交给格兰杰因果分析，这使得研究人员可以直接检查与处理特定类型信息相关的不同大脑区域的激活之间关系的因果模式。利用这些技术，本研究探讨了产生以下现象的机制：(1)语音的离散分类（分类感知）；(2)频率或语音致音效应对语音感知的影响；(3)语义语境对语音感知的影响。在确定了局部功能如何相互作用以在未受损的听者中产生强大的语言感知之后，这些工具将用于检查中风后18个月内单侧局灶性脑损伤后保存的过程如何重组和整合，以允许失语症患者的功能恢复。这些数据解决了关于大脑功能、人类语言感知的稳健性以及支持失语症患者康复的机制等核心的、以前无法解决的问题。作为基础研究，本研究对局灶性损伤患者的研究、评估和康复具有广泛的指导意义。

DESCRIPTION (provided by applicant): Research in the brain and cognitive sciences provides overwhelming evidence that even seemingly simple tasks like understanding spoken words rely on the interaction of a variety different types of information (e.g. auditory, phonetic, phonological, lexical, semantic etc.). These interactions are remarkable in that they appear to allow listeners, including many stroke patients with focal damage to brain regions that are responsible representing these types of information, to recognize spoken language, even when speech is unclear due to poor articulation, imperfect speech synthesis, noisy environments, or poor signal quality due to digital reduction or filtering (e.g. when experienced via cochlear implant, hearing aids, or a poor phone connection). There is still vigorous debate about the nature or necessity of many of these interactions due to intrinsic limitations in the interpretability of current behavioral and unimodal imaging paradigms. This proposal addresses these limitations by integrating MRI, MEG and EEG data to provide high spatiotemporal resolution images of evolving brain activation during speech perception tasks. These data will be submitted to Granger causality analysis, which allows researchers to directly examine patterns of cause and effect in the relationship between activation of different brain regions associated with the processing of specific types of information. Using these techniques, the proposed research examines the mechanisms that give rise to: (1) the discrete categorization of speech sounds (categorical perception), (2) frequency or phonotactic effects on the perception of speech sounds, (3) the influence of semantic context on speech perception. Having identified how localized functions interact to produce robust speech perception in unimpaired listeners, these tools will then be turned to examine how preserved processes are reorganized and integrated after unilateral focal brain damage in the 18 months following stroke, to allow the recovery of function in aphasic patients. These data address central, previously irresolvable questions about brain function, the robustness of human speech perception, and the mechanisms that support recovery in aphasic patients. As basic research, the work should have wide-reaching implications for the study, assessment, and rehabilitation of patients with focal damage. PUBLIC HEALTH RELEVANCE: Aphasia is a common neurological condition affecting the ability of roughly one million Americans to communicate using language (National Institute on Deafness and Other Communication Disorders, 1997). Despite the fact that aphasia is generally the result of irreversible brain damage, aphasics show differing levels of functional recovery associated and new patterns of brain activation during language tasks (Heiss & Thiel, 2006). The proposed work will characterize patterns of interaction in brain activity in unimpaired listeners and examine how these patterns of activation are integrated with preserved brain function to produce improved language understanding over time in people with aphasia.