Hierarchical Organization of Human Auditory Cortex: Evidence from Acoustic Invariance in the Response to Intelligible Speech
Hierarchical Organization of Human Auditory Cortex: Evidence from Acoustic Invariance in the Response to Intelligible Speech
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DOI：
10.1093/cercor/bhp318
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发表时间：
2010-10-01
期刊：
影响因子：
3.7
通讯作者：
Hickok, Gregory
中科院分区：
文献类型：
--
作者：
Okada, Kayoko;Rong, Feng;Hickok, Gregory
人类听觉皮层的层次组织已经从功能成像观察中推断出，核心区域对简单刺激（音调）做出反应，而下游区域选择性地对更复杂的刺激（带通噪声，语音）做出反应。假设核心区域编码低级别特征，这些特征在听觉系统中在更高级别组合以产生更抽象的神经代码。然而，这一假设尚未在听觉领域得到严格评估。我们使用功能性磁共振成像和多变量模式分析评估了可理解语音与不可理解语音对声学变化的敏感性。上级颞回背侧的核心听觉区域对声学特征表现出高水平的敏感性，而两侧的前上级颞沟和后上级颞沟（pSTS）的下游听觉区域对语音是否可理解表现出更高的敏感性，而对声学变化（声学不变性）的敏感性较低。声学不变性是最明显的两个半球，我们认为支持语音水平的代表在更多的pSTS地区。这一发现为人类听觉皮层的分层组织提供了直接证据，并阐明了支持可理解语音处理的皮层通路。
Hierarchical organization of human auditory cortex has been inferred from functional imaging observations that core regions respond to simple stimuli (tones) whereas downstream regions are selectively responsive to more complex stimuli (band-pass noise, speech). It is assumed that core regions code low-level features, which are combined at higher levels in the auditory system to yield more abstract neural codes. However, this hypothesis has not been critically evaluated in the auditory domain. We assessed sensitivity to acoustic variation within intelligible versus unintelligible speech using functional magnetic resonance imaging and a multivariate pattern analysis. Core auditory regions on the dorsal plane of the superior temporal gyrus exhibited high levels of sensitivity to acoustic features, whereas downstream auditory regions in both anterior superior temporal sulcus and posterior superior temporal sulcus (pSTS) bilaterally showed greater sensitivity to whether speech was intelligible or not and less sensitivity to acoustic variation (acoustic invariance). Acoustic invariance was most pronounced in more pSTS regions of both hemispheres, which we argue support phonological level representations. This finding provides direct evidence for a hierarchical organization of human auditory cortex and clarifies the cortical pathways supporting the processing of intelligible speech.