The Neural Bases of Statistical and Referential Cues to Phonetic Category Structu

描述（由申请人提供）：本研究的目的是探讨成人习得新语音类别能力的神经机制。具体来说，我们将研究输入的统计和参考属性的经验如何影响受试者对声学-语音连续体的感知敏感性，以及这些敏感性变化的神经相关性。这将通过使用功能性磁共振成像（fMRI）来测量成年受试者熟悉来自非母语语音连续体的听觉刺激的激活模式来完成。重要的是，在熟悉过程中呈现的听觉刺激的统计分布以及伴随听觉刺激的视觉/参考线索将会变化，以分离统计和参考线索与语音类别识别的神经关联。神经结构对连续体上不同位置等效声间隔的敏感性将使用短间隔习惯化范式进行探讨，其中fMR信号的适应释放被用作神经对语音类别结构变化敏感性的标记。本研究认为，颞后上回等区域的激活变化作为熟悉的功能，表明语音类别结构的变化在语音加工流的早期被介导。另外，额叶（额下回）和顶叶（边缘上回、角回）结构的激活变化表明，语音类别的扭曲发生在加工流的后期，反映了注意力、词汇或执行系统的补充。结果将阐明统计和参考线索塑造感知敏感性的过程，最终形成语音类别的基础。

DESCRIPTION (provided by applicant): The goal of this research is to investigate the neural mechanisms which underlie adults' ability to acquire new phonetic categories. Specifically, we will investigate how experience with statistical and referential properties of the input shapes subjects' perceptual sensitivities to items along an acoustic-phonetic continuum, and the neural correlates of these changes in sensitivity. This will be accomplished by using functional MRI (fMRI) to measure activation patterns in adult subjects who have been familiarized with auditory stimuli taken from a non-native phonetic continuum. Importantly, the statistical distribution of the auditory stimuli presented during familiarization, as well as the visual/referential cues which accompany the auditory stimuli will be varied in order to isolate neural correlates of statistical and referential cues to phonetic category identity. Sensitivity of neural structures to equivalent acoustic intervals at different locations along the continuum will be probed using a short-interval habituation paradigm, in which release from adaptation of the fMR signal is used as a marker for neural sensitivity to changes in phonetic category structure. It is argued that changes in activation as a function of familiarization in such areas as the posterior superior temporal gyrus would suggest that the changes in phonetic category structure are mediated early in the phonetic processing stream. Alternatively, changes in activation in the frontal (inferior frontal gyrus) and parietal (supramarginal gyrus, angular gyrus) structures would suggest that the warping of phonetic categories occurs later in the processing stream and reflects the recruitment of attentional, lexical, or executive systems. Results will shed light on the process by which statistical and referential cues shape perceptual sensitivities which ultimately form the basis of phonetic categories. Relevance: The proposed research will shed light on the neural mechanisms which underlie the acquisition of phonetic categories, and may ultimately be used to inform treatment strategies for children with developmental language disorders. Additionally, results should add to our understanding of the neural bases of speech processing in adults, which may be used to suggest rehabilitative strategies for aphasic patients who have suffered language impairments due brain injury.