Interdependent encoding of pitch, timbre, and spatial location in auditory cortex.
Interdependent encoding of pitch, timbre, and spatial location in auditory cortex.
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DOI：
10.1523/jneurosci.4755-08.2009
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发表时间：
2009-02-18
期刊：
影响因子：
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通讯作者：
Schnupp JW
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文献类型：
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作者：
Bizley JK;Walker KM;Silverman BW;King AJ;Schnupp JW
因为我们可以独立地感知声源的音高、音色和空间位置，所以很自然地假设声音的皮层处理可能会将空间属性与非空间属性分开。事实上，最近的研究支持解剖学上分离的“什么”和“哪里”皮质处理流的存在。然而，很少有人尝试测量不同皮层区域中的单个神经元对在空间和非空间维度上同时变化的声音的反应。我们记录了对虚拟声学空间中呈现的人工元音的反应，以研究雪貂听觉皮层的核心和带区域中的音调、音色和声源方位角的表示。使用方差分解技术来量化改变每个参数改变神经反应的方式。大多数单位对这些刺激属性中的两个或多个都很敏感。虽然表明音调、位置和音色线索的神经编码分布在整个听觉皮层，但在皮层区域和深度上观察到平均神经元敏感性的显着差异，这可能构成较高皮层水平上空间和非空间线索分离的基础。一些单元在音高、音色和方位角的特定组合之间表现出显着的非线性相互作用。这些相互作用对于音高和音色最为明显，而在空间和非空间属性之间则不太常见。这种非线性在初级听觉皮层中最为普遍，尽管与刺激的主效应相比它们往往较小。
Because we can perceive the pitch, timbre and spatial location of a sound source independently, it seems natural to suppose that cortical processing of sounds might separate out spatial from non-spatial attributes. Indeed, recent studies support the existence of anatomically segregated ‘what’ and ‘where’ cortical processing streams. However, few attempts have been made to measure the responses of individual neurons in different cortical fields to sounds that vary simultaneously across spatial and non-spatial dimensions. We recorded responses to artificial vowels presented in virtual acoustic space to investigate the representations of pitch, timbre and sound source azimuth in both core and belt areas of ferret auditory cortex. A variance decomposition technique was used to quantify the way in which altering each parameter changed neural responses. Most units were sensitive to two or more of these stimulus attributes. Whilst indicating that neural encoding of pitch, location and timbre cues is distributed across auditory cortex, significant differences in average neuronal sensitivity were observed across cortical areas and depths, which could form the basis for the segregation of spatial and non-spatial cues at higher cortical levels. Some units exhibited significant non-linear interactions between particular combinations of pitch, timbre and azimuth. These interactions were most pronounced for pitch and timbre and were less commonly observed between spatial and non-spatial attributes. Such non-linearities were most prevalent in primary auditory cortex, although they tended to be small compared with stimulus main effects.