Reexamining the Evidence for a Pitch-Sensitive Region: A Human fMRI Study Using Iterated Ripple Noise
Reexamining the Evidence for a Pitch-Sensitive Region: A Human fMRI Study Using Iterated Ripple Noise
复制标题
DOI：
10.1093/cercor/bhr065
复制
发表时间：
2012-04-01
期刊：
影响因子：
3.7
通讯作者：
Hall, Deborah A.
中科院分区：
文献类型：
--
作者：
Barker, Daphne;Plack, Christopher J.;Hall, Deborah A.
人类神经成像研究已经确定了听觉皮质的一个区域，即外侧Heschl‘s回(HG)，它对迭代涟漪噪声(IRN)的反应比对高斯噪声的控制更大。部分基于使用IRN作为音高刺激的结果，有人认为侧向HG是一个一般的“音调中心”。然而，IRN包含与音调无关的缓慢变化的光谱时间调制，这在控制刺激中没有发现。因此，大脑皮层对IRN的反应可能部分是由这些调节机制驱动的。目前的研究首次尝试对这些调节进行控制。这是通过使用一种新型的刺激来实现的，这种刺激是通过处理IRN来去除精细的时间结构(从而去除音调)，但保留缓慢变化的调制。这种“无音调IRN”刺激被称为IRNo。结果表明，整个听觉皮质对频域时间调制有广泛的反应。当IRN与IRNo而不是与高斯噪声进行对比时，基音的明显影响不再具有统计学意义。我们的发现提出了一种可能性，即与音调无关的大脑皮层反应之前可能被错误地归因于音调编码。
Human neuroimaging studies have identified a region of auditory cortex, lateral Heschl's gyrus (HG), that shows a greater response to iterated ripple noise (IRN) than to a Gaussian noise control. Based in part on results using IRN as a pitch-evoking stimulus, it has been argued that lateral HG is a general "pitch center." However, IRN contains slowly varying spectrotemporal modulations, unrelated to pitch, that are not found in the control stimulus. Hence, it is possible that the cortical response to IRN is driven in part by these modulations. The current study reports the first attempt to control for these modulations. This was achieved using a novel type of stimulus that was generated by processing IRN to remove the fine temporal structure (and thus the pitch) but leave the slowly varying modulations. This "no-pitch IRN" stimulus is referred to as IRNo. Results showed a widespread response to the spectrotemporal modulations across auditory cortex. When IRN was contrasted with IRNo rather than with Gaussian noise, the apparent effect of pitch was no longer statistically significant. Our findings raise the possibility that a cortical response unrelated to pitch could previously have been errantly attributed to pitch coding.