Gourévitch Boris, Le Bouquin Jeannès Régine, Faucon Gérard, Liégeois-Chauvel Catherine
INSERM, U642, Rennes, F-35000, France.
Hear Res. 2008 Mar;237(1-2):1-18. doi: 10.1016/j.heares.2007.12.003. Epub 2007 Dec 28.
Temporal envelope processing in the human auditory cortex has an important role in language analysis. In this paper, depth recordings of local field potentials in response to amplitude modulated white noises were used to design maps of activation in primary, secondary and associative auditory areas and to study the propagation of the cortical activity between them. The comparison of activations between auditory areas was based on a signal-to-noise ratio associated with the response to amplitude modulation (AM). The functional connectivity between cortical areas was quantified by the directed coherence (DCOH) applied to auditory evoked potentials. This study shows the following reproducible results on twenty subjects: (1) the primary auditory cortex (PAC), the secondary cortices (secondary auditory cortex (SAC) and planum temporale (PT)), the insular gyrus, the Brodmann area (BA) 22 and the posterior part of T1 gyrus (T1Post) respond to AM in both hemispheres. (2) A stronger response to AM was observed in SAC and T1Post of the left hemisphere independent of the modulation frequency (MF), and in the left BA22 for MFs 8 and 16Hz, compared to those in the right. (3) The activation and propagation features emphasized at least four different types of temporal processing. (4) A sequential activation of PAC, SAC and BA22 areas was clearly visible at all MFs, while other auditory areas may be more involved in parallel processing upon a stream originating from primary auditory area, which thus acts as a distribution hub. These results suggest that different psychological information is carried by the temporal envelope of sounds relative to the rate of amplitude modulation.
人类听觉皮层中的时间包络处理在语言分析中具有重要作用。在本文中，利用对调幅白噪声做出响应的局部场电位深度记录来设计初级、次级和联合听觉区域的激活图谱，并研究它们之间皮质活动的传播。听觉区域之间激活情况的比较基于与调幅（AM）响应相关的信噪比。通过应用于听觉诱发电位的定向相干性（DCOH）对皮质区域之间的功能连接进行量化。这项研究在20名受试者身上得出了以下可重复的结果：（1）双侧的初级听觉皮层（PAC）、次级皮层（次级听觉皮层（SAC）和颞平面（PT））、脑岛回、布罗德曼区（BA）22以及T1回后部（T1Post）对调幅有反应。（2）与右侧相比，在左侧半球的SAC和T1Post中观察到对调幅更强的反应，且与调制频率（MF）无关；在左侧BA22中，对于8Hz和16Hz的MF，反应更强。（3）激活和传播特征强调了至少四种不同类型的时间处理。（4）在所有MF下，PAC、SAC和BA22区域的顺序激活清晰可见，而其他听觉区域可能更多地参与源自初级听觉区域的信息流的并行处理，因此初级听觉区域起到了分布枢纽的作用。这些结果表明，相对于调幅速率，声音的时间包络携带了不同的心理信息。
