Spectrotemporal features of the auditory cortex: the activation in response to dynamic ripples
Spectrotemporal features of the auditory cortex: the activation in response to dynamic ripples
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DOI：
10.1016/s1053-8119(03)00258-1
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发表时间：
2003-09-01
期刊：
影响因子：
5.7
通讯作者：
van Dijk, P
中科院分区：
文献类型：
--
作者：
Langers, DRM;Backes, WH;van Dijk, P
本文应用功能磁共振成像技术研究了人脑对动态波纹的反应特征。动态波纹是包含有规律的频谱时间调制的声音刺激，这在语音处理中非常重要;然而，与语音相反，动态波纹可以完全由有限数量的参数来表征。在听觉皮层的两侧发现了由多个独立区域组成的广泛激活，特别是沿着Heschl's gyri。这与结构性皮层细分为功能性区域的存在相一致。测量激活的水平和程度，并高度相关（R-2 = 0.97）。这两种措施强烈依赖于频谱密度，时间频率和调制的幅度，并匹配的感知spectrotemporal调制的可识别性。最大的反应发生在接近最佳人体灵敏度的参数值。调制的漂移方向不影响激活。在两个半球之间没有发现数量上的差异。平均大脑激活水平被证明是可分离的调制的频谱密度和时间频率方面。拓扑映射的调制密度和频率到皮质表面上显示，大约在后外侧到前内侧和外侧到内侧的方向，分别。后外侧区是最敏感的spectrotemporal功能在一个规模类似的音素。然而，前内侧区域对较小尺度的声学特征也相对敏感。这种空间依赖的敏感性表明听觉皮层的功能地形和层次组织。(C)2003年爱思唯尔公司All rights reserved.
Functional MRI was used to investigate the characteristics of the human cerebral response to dynamic ripples. Dynamic ripples are sound stimuli containing regular spectrotemporal modulations, which are of major importance in speech processing; however, in contrast to speech, dynamic ripples can be characterized fully by a limited number of parameters. Extensive activation consisting of multiple separate regions was found bilaterally in the auditory cortex, particularly along the Heschl's gyri. This agrees with the presence of a structural cortical subdivision into functional fields. The level and the extent of activation were measured and correlated highly (R-2 = 0.97). Both measures depended strongly on the spectral density, temporal frequency, and amplitude of the modulations and matched the perceptual discernibility of the spectrotemporal modulations. The largest responses occurred for parameter values near the optimal human sensitivity. The drift direction of the modulations did not influence the activation. No quantitative differences were found between the two hemispheres. Average brain activation levels proved to be separable with regard to the spectral density and temporal frequency of the modulations. Topographic mappings of the modulation density and frequency onto the cortical surface were shown, approximately in posterolateral-to-anteromedial and lateral-to-medial directions, respectively. Posterolateral regions were most sensitive to spectrotemporal features at a scale similar to phonemes. Anteromedial regions, however, were also relatively sensitive to smaller scale acoustic features. This spatially dependent sensitivity suggests a functional topographic and hierarchical organization of the auditory cortex. (C) 2003 Elsevier Inc. All rights reserved.