Neural Basis of Lexical and Speech Processing

描述（由申请人提供）：本研究的目标是探索语音和词汇处理的两个关键方面的神经系统：听众如何感知一个稳定的语音识别，尽管有许多可变性来源（对象恒常性/不变性问题），以及他们如何成功地选择合适的候选词从许多字，共享声音形状属性（语音竞争的决议）。一系列的实验将调查语音类别跨元音环境和不同的扬声器的不变性，和发音的语音特征跨发音的位置和方式的变化和发音的方式跨语音和发音的位置的变化的不变性。一个fMRI适应范例将用于识别语音处理流中的大脑区域，这些区域在不同的变异源下显示出不变的神经反应。颞区的不变神经反应表明，语音不变性来自不变的声学模式。额区（包括额下回（IFG）、运动前区和运动区）的不变神经反应表明，语音不变性来自共同的运动/发音手势。顶叶区的不变神经反应表明，语音恒定性来自更高层次的抽象语音表征。在发音区没有激活的情况下，IFG中不变的神经反应表明语音恒定性是由决策相关过程决定的。第二个系列的实验将研究在语音竞争条件下招募的大脑区域。据推测，IFG服务的域一般的作用，因此将被招募的条件下的语音竞争。然而，据推测，IFG是不响应的刺激的语音特性中固有的竞争，但只在竞争的决议，即当竞争表示被激活，一个字需要从这些竞争表示中选择招募。与此相反，有人假设，SMG被招募在访问的词汇形式的一个词，无论选择的要求与激活调制的程度的语音竞争。最后，它提出，语音竞争招聘相同的神经系统在听觉单词识别和口语单词的生产。在听觉词识别中，将使用眼动追踪范式来研究起始竞争、词汇密度和语音介导的竞争。在口语单词的产生，单词阅读和图片命名范式将被用来调查生产的话，没有发声的竞争对手，生产的话，从高密度与低密度的邻居，和生产的话，在相同的语音竞争对手集与那些不相同的竞争对手集。公共卫生相关性这项拟议中的研究增加了我们对涉及语音和文字处理的大脑区域的了解。这些结果提供了关键的基线数据，用于了解脑损伤失语症患者的这种缺陷的基础，用于识别脑损伤后恢复过程中可能招募的大脑区域，以及为言语和语言缺陷患者制定潜在的康复策略。所提出的理论途径和方法可以应用于其他认知系统，为探索其他认知过程的大脑功能提供了一种手段。

DESCRIPTION (provided by applicant): The goal of this research is to explore the neural systems underlying two critical aspects of speech and lexical processing: how listeners perceive a stable phonetic percept despite many sources of variability (the object constancy/invariance problem) and how they successfully select the appropriate word candidate from the many words that share sound shape properties (the resolution of phonological competition). One series of experiments will investigate invariance for phonetic categories across vowel environments and different speakers, and invariance for the phonetic feature of voicing across variations in place and manner of articulation and manner of articulation across variations in voice and place of articulation. An fMRI-adaptation paradigm will be used to identify brain regions in the phonetic processing stream that show invariant neural responses under different sources of variability. Invariant neural responses in temporal areas would suggest that phonetic invariance derives from invariant acoustic patterns. Invariant neural responses in frontal areas including the inferior frontal gyrus (IFG), premotor, and motor areas would suggest that phonetic invariance derives from shared motor/articulatory gestures. Invariant neural responses in parietal areas would suggest that phonetic constancy derives from higher order abstract phonological representations. And invariant neural responses in the IFG in the absence of activation of articulatory areas would suggest that phonetic constancy is determined by decision-related processes. A second series of experiments will investigate the brain regions recruited under conditions of phonological competition. It is hypothesized that the IFG serves a domain general role and hence will be recruited under conditions of phonological competition. However, it is hypothesized that the IFG is not responsive to competition inherent in the phonological properties of the stimulus but is recruited only in the resolution of competition, i.e. when competing representations are activated and a word needs to be selected from among these competing representations. In contrast, it is hypothesized that the SMG is recruited in accessing the lexical form of a word irrespective of selection demands with activation modulated by the degree of phonological competition. Finally, it is proposed that phonological competition recruits the same neural systems in both auditory word recognition and spoken word production. In auditory word recognition, an eyetracking paradigm will be used to investigate onset competition, lexical density, and phonologically mediated competition. In spoken word production, word reading and picture naming paradigms will be used to investigate the production of words with and without voiced competitors, the production of words from high versus low density neighborhoods, and the production of words presented in the same phonological competitor set versus those not in the same competitor set. PUBLIC HEALTH RELEVANCE The proposed research adds to our knowledge of the brain areas involved in the processing of speech and words. The results provide critical baseline data for understanding the bases of such deficits in brain-injured patients with aphasia, for identifying those areas of the brain that may be recruited in recovery processes subsequent to brain injury, and for potentially developing rehabilitative strategies for patients with speech and language deficits. The theoretical approach and methods proposed can be applied to other cognitive systems, providing a means of exploring brain function underlying other cognitive processes.