Neural correlates of switching from auditory to speech perception
Neural correlates of switching from auditory to speech perception
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DOI：
10.1016/j.neuroimage.2004.09.039
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发表时间：
2005-01-01
期刊：
影响因子：
5.7
通讯作者：
Dehaene, S
中科院分区：
文献类型：
--
作者：
Dehaene-Lambertz, G;Pallier, C;Dehaene, S
许多人接触到类似于正弦波的语音，首先报告说听到的是电子滑音，后来，当他们切换到语音模式时，听到的是音节。这种感知转换改变了他们的辨别能力，增强了对跨越音素边界的差异的感知，同时减少了对音素类别内差异的感知。使用高密度诱发电位和功能磁共振成像在一个歧视的范例，我们研究了大脑活动的变化，与这种变化的看法。通过ERPs，我们观察到音素编码比声学编码更快：音素变化的电生理失配反应（MMR）比等效声学变化更早发生。的MMR地形也更不对称的音位变化比声学的变化。在功能磁共振成像中，激活也显着不对称，有利于左半球在两种感知模式。此外，相对于非语音模式，切换到语音模式显著增强了左侧上级回和沟后部的激活。当对刺激变化的反应进行了研究，一个集群的体素在边缘上的陀螺仪被激活显着更多的音位变化比声学变化。这些结果表明，成年人的音素知觉依赖于一个特定的和高效的左半球网络，它可以被激活在自上而下的方式处理模糊的语音/非语音刺激。(C)2004年爱思唯尔公司All rights reserved.
Many people exposed to sinewave analogues of speech first report hearing them as electronic glissando and, later, when they switch into a,speech mode', hearing them as syllables. This perceptual switch modifies their discrimination abilities, enhancing perception of differences that cross phonemic boundaries while diminishing perception of differences within phonemic categories. Using high-density evoked potentials and fMRI in a discrimination paradigm, we studied the changes in brain activity that are related to this change in perception. With ERPs, we observed that phonemic coding is faster than acoustic coding: The electrophysiological mismatch response (MMR) occurred earlier for a phonemic change than for an equivalent acoustic change. The MMR topography was also more asymmetric for a phonemic change than for an acoustic change. In fMRI, activations were also significantly asymmetric, favoring the left hemisphere in both perception modes. Furthermore, switching to the speech mode significantly enhanced activation in the posterior parts of the left superior gyros and sulcus relative to the non-speech mode. When responses to a change of stimulus were studied, a cluster of voxels in the supramarginal gyros was activated significantly more by a phonemic change than by an acoustic change. These results demonstrate that phoneme perception in adults relies on a specific and highly efficient left-hemispheric network, which can be activated in top-down fashion when processing ambiguous speech/non-speech stimuli. (C) 2004 Elsevier Inc. All rights reserved.