Spectro-temporal modulation transfer function of single voxels in the human auditory cortex measured with high-resolution fMRI
Spectro-temporal modulation transfer function of single voxels in the human auditory cortex measured with high-resolution fMRI
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DOI：
10.1073/pnas.0907682106
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发表时间：
2009-08-25
影响因子：
11.1
通讯作者：
Zatorre, Robert J.
中科院分区：
文献类型：
--
作者：
Schoenwiesner, Marc;Zatorre, Robert J.
视觉和听觉刺激在人类大脑皮层的处理机制是否相似？图像可以被认为是两个空间维度上的光能调制，低水平视觉区域通过分解成空间频率来分析图像。同样，声音是随时间和频率变化的能量调制，它们可以通过这种调制的内容来识别和区分。因此，一个明显的问题是，人类的听觉区域是否与视觉区域直接类比，代表了声刺激的光谱-时间调制内容。为了回答这个问题，我们用功能性磁共振成像测量了人类听觉皮层单个体素的光谱-时间调制传递函数。我们提出了动态波纹，复杂的宽带刺激与漂移正弦频谱包络。动态波纹是视觉系统研究中经常使用的光栅的听觉等效物。我们展示了选择性调谐结合光谱-时间调制在初级和次级听觉皮层。我们描述了几种类型的调制传递函数，提取了不同的光谱-时间特征，光谱和时间参数之间具有高度的相互作用。大脑皮层的整体低通调制率偏好与自然声音的调制内容相匹配。这些结果表明，人类听觉皮层中存在光谱-时间复合调制，并表明复杂信号根据其调制内容进行分解和处理，这与视觉系统使用的转换相同。
Are visual and auditory stimuli processed by similar mechanisms in the human cerebral cortex? Images can be thought of as light energy modulations over two spatial dimensions, and low-level visual areas analyze images by decomposition into spatial frequencies. Similarly, sounds are energy modulations over time and frequency, and they can be identified and discriminated by the content of such modulations. An obvious question is therefore whether human auditory areas, in direct analogy to visual areas, represent the spectro-temporal modulation content of acoustic stimuli. To answer this question, we measured spectro-temporal modulation transfer functions of single voxels in the human auditory cortex with functional magnetic resonance imaging. We presented dynamic ripples, complex broadband stimuli with a drifting sinusoidal spectral envelope. Dynamic ripples are the auditory equivalent of the gratings often used in studies of the visual system. We demonstrate selective tuning to combined spectro-temporal modulations in the primary and secondary auditory cortex. We describe several types of modulation transfer functions, extracting different spectro-temporal features, with a high degree of interaction between spectral and temporal parameters. The overall low-pass modulation rate preference of the cortex matches the modulation content of natural sounds. These results demonstrate that combined spectro-temporal modulations are represented in the human auditory cortex, and suggest that complex signals are decomposed and processed according to their modulation content, the same transformation used by the visual system.