Neocortical Mechanisms of Categorical Speech Perception

口语理解的基本机制尚不清楚。例如，我们不理解人类大脑如何从复杂且高度可变的声学信号中提取最基本的语言元素（辅音和元音）。对范畴知觉过程中语音的皮层表征的研究可能会揭示这个基本问题。范畴感知发生在当一个变量的变化，如音位对比沿着一个连续统被感知，而不是作为一个渐进的功能，而是作为一个离散的类别变化。先前的研究表明，上级颞叶皮层参与了语音的处理。然而，大脑皮层实际上是如何代表（即编码）音素是不确定的，主要是由于非侵入性记录技术的限制。 直接从皮层表面记录神经活动是一种很有前途的方法，因为它可以提供高的空间和时间分辨率。在这里，我建议利用神经外科手术过程中获得的神经生理学记录来检查分类语音处理的机制。独立的ROO阶段的主要焦点将是阐明上级颞叶回的音素的涌现不变表征，这是范畴知觉的基础。高密度电极分析，先进的信号处理，和直接电皮层刺激将被用来解开两个本地人口的语音编码在侧颞叶皮层，以及全球处理跨多个感官和认知领域。

The basic mechanisms underlying comprehension of spoken language are unknown. We do not understand, for example, how the human brain extracts the most fundamental linguistic elements (consonants and vowels) from a complex and highly variable acoustic signal. An investigation of the cortical representation of speech sounds during categorical perception can likely shed light on this fundamental question. Categorical perception occurs when a change in a variable such as phonem ic contrast along a continuum is perceived, not as a gradual function but rather as a discrete category change. Previous research has implicated the superior temporal cortex in the processing Of speech sounds. However, how the cortex actually represents (i.e. encodes) phonemes is undetermined, mainly due to limitations of non-invasive recording techniques. The recording of neural activity di rectly from the cortical surface is a promising approach si nee it can provide both high spatial and temporal resolution. Here, I propose to examine the mechanisms of categorical speech processing by utilizing neurophysiological recordings obtained during ne urosurgical pnacedures. The principal focus of the independent ROO phase wil I be to elucidate the emergent invariant representation of phonemes in the superior tem poral gyrus that underiies categorical perception. High-density electrode anays, advanced signal processing, and direct eiectrocortical stim ulation will be utilized to unravel both local population encoding of speec h sounds in the lateral temporal cortex as well as global processing across multiple sensory and cognitiv e areas.