Electrocorticographic Study of Categorical Phoneme Perception in the Human Tempor

描述（由申请人提供）：语音感知的基本机制尚不清楚。人类听觉系统有规律地将高度声学可变的输入处理成不变的语音表示——这是人类交流的关键功能。为了更好地理解这一特性，我建议研究分类感知（CP）过程中语音的皮层表征。当感知到一个变量的变化，如沿着物理连续体的音位对比，不是渐进的，而是作为一个离散类别的实例时，就会发生CP。先前的功能性神经影像学研究已经表明，颞上回和颞外侧皮层的沟参与音素处理，但不清楚皮层代表这些声音的确切方式。在为期一年的培训计划中，我计划使用皮质电图（ECoG），直接将电极应用于大脑表面以记录皮层活动，来检查颞上回的分类语音处理。我将利用高密度脑电图阵列和信号分析技术，在被动听语音刺激的6例癫痫患者慢性植入硬脑膜下网格。语音辨别和识别行为任务将在术前进行，并在其他健康的正常受试者中进行，以确定CP转换的边界。音素刺激将集中于与众所周知的分类心理物理特性的三个对比：/b/ vs /d/， /r/ vs /I/和/d/ vs /t/。我们假设，诱发电位和/或神经振荡活动的高度特定时空模式将揭示语音音位对比的紧急分类表征，该表征密切反映行为阈值，而不是声学参数的连续线性表征。提高对言语处理机制的理解对包括自闭症、阅读障碍和语言学习障碍在内的交流障碍的起源和补救具有直接意义。

DESCRIPTION (provided by applicant): The basic mechanisms underlying speech perception are unclear. The human auditory system regularly processes highly acoustically variable inputs into invariant representations of speech- a critical function for human communication. In order to better understand this property, I propose to investigate the cortical representations of speech sounds during categorical perception (CP). CP occurs when a change in a variable such a phonemic contrast along a physical continuum is perceived, not as gradual but as an instance of discrete category. Previous functional neuroimaging research has implicated the superior temporal gyrus and sulcus of the lateral temporal cortex in phonemic processing, but not the precise means by which the cortex represents those sounds. During a one-year training program, I plan to use electrocorticography (ECoG), the direct application of electrodes to the brain surface for recording cortical activity, to examine categorical speech processing in the superior temporal gyrus. I will utilize a high-density ECoG array and signal analysis techniques during passive listening to speech stimuli in six epilepsy patients with chronic implanted subdural grids. Phonetic discrimination and identification behavioral tasks will be performed pre-operatively, and in additional healthy normal subjects, to determine boundaries for CP transitions. Phoneme stimuli will focus on three contrasts with well-known categorical psychophysical properties: /b/ vs /d/, /r/ vs /I/, and /d/ vs /t/. We hypothesize that a highly specific spatiotemporal pattern of evoked potential and/or neural oscillatory activity will reveal an emergent categorical representation of speech phonemic contrasts which closely reflects behavioral thresholds, as opposed to a continuously linear representation of acoustic parameters. An improved understanding of speech processing mechanisms has direct implications for the origin and remediation of communication disorders, including autism, dyslexia, and language learning impairment.