Riedel Philipp, Ragert Patrick, Schelinski Stefanie, Kiebel Stefan J, von Kriegstein Katharina
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Deptartment of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Neuroimaging Center, Technische Universität Dresden, Dresden, Germany.
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Cortex. 2015 Jul;68:86-99. doi: 10.1016/j.cortex.2014.11.016. Epub 2014 Dec 23.
It is commonly assumed that the recruitment of visual areas during audition is not relevant for performing auditory tasks ('auditory-only view'). According to an alternative view, however, the recruitment of visual cortices is thought to optimize auditory-only task performance ('auditory-visual view'). This alternative view is based on functional magnetic resonance imaging (fMRI) studies. These studies have shown, for example, that even if there is only auditory input available, face-movement sensitive areas within the posterior superior temporal sulcus (pSTS) are involved in understanding what is said (auditory-only speech recognition). This is particularly the case when speakers are known audio-visually, that is, after brief voice-face learning. Here we tested whether the left pSTS involvement is causally related to performance in auditory-only speech recognition when speakers are known by face. To test this hypothesis, we applied cathodal transcranial direct current stimulation (tDCS) to the pSTS during (i) visual-only speech recognition of a speaker known only visually to participants and (ii) auditory-only speech recognition of speakers they learned by voice and face. We defined the cathode as active electrode to down-regulate cortical excitability by hyperpolarization of neurons. tDCS to the pSTS interfered with visual-only speech recognition performance compared to a control group without pSTS stimulation (tDCS to BA6/44 or sham). Critically, compared to controls, pSTS stimulation additionally decreased auditory-only speech recognition performance selectively for voice-face learned speakers. These results are important in two ways. First, they provide direct evidence that the pSTS is causally involved in visual-only speech recognition; this confirms a long-standing prediction of current face-processing models. Secondly, they show that visual face-sensitive pSTS is causally involved in optimizing auditory-only speech recognition. These results are in line with the 'auditory-visual view' of auditory speech perception, which assumes that auditory speech recognition is optimized by using predictions from previously encoded speaker-specific audio-visual internal models.
人们通常认为，在听觉过程中视觉区域的激活与执行听觉任务无关（“仅听觉观点”）。然而，另一种观点认为，视觉皮层的激活被认为可以优化仅听觉任务的表现（“听觉-视觉观点”）。这种另一种观点基于功能磁共振成像（fMRI）研究。例如，这些研究表明，即使只有听觉输入，后颞上沟（pSTS）内对面部运动敏感的区域也参与理解所说内容（仅听觉语音识别）。当说话者通过视听方式被认出来时，也就是在短暂的语音-面部学习之后，情况尤其如此。在这里，我们测试了在通过面部识别说话者时，左侧pSTS的参与是否与仅听觉语音识别的表现存在因果关系。为了验证这一假设，我们在以下两种情况下对pSTS施加阴极经颅直流电刺激（tDCS）：（i）参与者仅通过视觉认识的说话者的仅视觉语音识别过程中，以及（ii）他们通过语音和面部学习认识的说话者的仅听觉语音识别过程中。我们将阴极定义为活性电极，通过使神经元超极化来下调皮层兴奋性。与未进行pSTS刺激的对照组（对BA6/44进行tDCS或假刺激）相比，对pSTS进行tDCS会干扰仅视觉语音识别表现。至关重要的是，与对照组相比，pSTS刺激还会选择性地降低仅通过语音-面部学习认识的说话者的仅听觉语音识别表现。这些结果在两个方面很重要。首先，它们提供了直接证据，证明pSTS因果性地参与了仅视觉语音识别；这证实了当前面部处理模型的一个长期预测。其次，它们表明视觉面部敏感的pSTS因果性地参与了优化仅听觉语音识别。这些结果与听觉语音感知的“听觉-视觉观点”一致，该观点假设听觉语音识别通过使用来自先前编码的特定说话者视听内部模型的预测来优化。
