Kang Eunjoo, Lee Dong Soo, Kang Hyejin, Hwang Chan Ho, Oh Seung-Ha, Kim Chong-Sun, Chung June-Key, Lee Myung Chul
Department of Nuclear Medicine, Seoul National University, 28 Yeongeon-dong, Jongno-gu, Seoul 110-744, Republic of Korea.
Neuroimage. 2006 Aug 1;32(1):423-31. doi: 10.1016/j.neuroimage.2006.03.016. Epub 2006 Apr 27.
Speech perception in face-to-face conversation involves processing of speech sounds (auditory) and speech-associated mouth/lip movements (visual) from a speaker. Using PET where no scanner noise was present, brain regions involved in speech cue processing were investigated with the normal hearing subjects with no previous lip-reading training (N = 17) carrying out a semantic plausibility decision on spoken sentences delivered in a movie file. Multimodality was ensured at the sensory level in all four conditions. Sensory-specific speech cue of one sensory modality, i.e., auditory speech (A condition) or mouth movement (V condition), was delivered with a control stimulus of the other modality whereas speech cues of both sensory modalities (AV condition) were delivered during bimodal condition. In comparison to the control condition, extensive activations in the superior temporal regions were observed bilaterally during the A condition but these activations were reduced in extent and left lateralized during the AV condition. Polymodal region such as left posterior superior temporal sulcus (pSTS) involved in cross-modal interaction/integration of audiovisual speech was found to be activated during the A and more so during the AV conditions but not during the V condition. Activations were observed in Broca's (BA 44), medial frontal (BA 8), and anterior ventrolateral prefrontal (BA 47) regions in the left during the V condition, where lip-reading performance was less successful. Results indicated that the speech-associated lip movements (visual speech cue) rendered suppression on the activity in the right auditory temporal regions. Overadditivity (AV > A + V) observed in the right postcentral region during the bimodal condition relative to the sum of unimodal speech conditions was also associated with reduced activity during the V condition. These findings suggested that visual speech cue could exert an inhibitory modulatory effect on the brain activities in the right hemisphere during the cross-modal interaction of audiovisual speech perception.
在面对面交谈中的言语感知涉及对说话者的语音（听觉）和与言语相关的口部/唇部动作（视觉）进行处理。使用在无扫描仪噪音的情况下的正电子发射断层扫描（PET），对17名未经唇读训练的听力正常受试者进行研究，这些受试者对电影文件中播放的口语句子进行语义合理性判断，以此来探究参与言语线索处理的脑区。在所有四种情况下，都在感官层面确保了多模态。一种感官模态的特定感官言语线索，即听觉言语（A条件）或口部动作（V条件），与另一种模态的控制刺激同时呈现，而在双模态条件下则同时呈现两种感官模态的言语线索（AV条件）。与对照条件相比，在A条件下双侧颞上区观察到广泛激活，但在AV条件下，这些激活范围缩小且向左半球侧化。发现参与视听言语跨模态交互/整合的多模态区域，如左后颞上沟（pSTS），在A条件下被激活，在AV条件下激活更明显，但在V条件下未被激活。在V条件下，左侧的布洛卡区（BA 44）、内侧额叶（BA 8）和前腹外侧前额叶（BA 47）区域出现激活，此时唇读表现不太成功。结果表明，与言语相关的唇部动作（视觉言语线索）对右侧听觉颞区的活动产生了抑制作用。在双模态条件下，相对于单模态言语条件的总和，右侧中央后区观察到的超相加性（AV > A + V）也与V条件下的活动减少有关。这些发现表明，在视听言语感知的跨模态交互过程中，视觉言语线索可能对右半球的脑活动发挥抑制性调节作用。
