Neocortical Mechanisms of Categorical Speech Perception

口语理解的基本机制尚不清楚。例如，我们不明白人脑如何从复杂多变的声音信号中提取最基本的语言元素（辅音和元音）。对分类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。范畴知觉发生时，一个变量的变化，如音位对比沿着一个连续体被感知，而不是作为一个渐进的功能，而是作为一个离散的范畴变化。先前的研究表明，颞上皮层参与了语音的处理。然而，由于非侵入性记录技术的限制，大脑皮层实际上是如何表示（即编码）音素的尚不确定。

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.