Sammler Daniela, Grosbras Marie-Hélène, Anwander Alfred, Bestelmeyer Patricia E G, Belin Pascal
Otto Hahn Group Neural Bases of Intonation in Speech, Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany; Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QB, UK.
Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QB, UK; Laboratoire de Neurosciences Cognitives, FR 3C, Aix-Marseille Université, 13331 Marseille, France.
Curr Biol. 2015 Dec 7;25(23):3079-85. doi: 10.1016/j.cub.2015.10.009. Epub 2015 Nov 5.
Our vocal tone--the prosody--contributes a lot to the meaning of speech beyond the actual words. Indeed, the hesitant tone of a "yes" may be more telling than its affirmative lexical meaning. The human brain contains dorsal and ventral processing streams in the left hemisphere that underlie core linguistic abilities such as phonology, syntax, and semantics. Whether or not prosody--a reportedly right-hemispheric faculty--involves analogous processing streams is a matter of debate. Functional connectivity studies on prosody leave no doubt about the existence of such streams, but opinions diverge on whether information travels along dorsal or ventral pathways. Here we show, with a novel paradigm using audio morphing combined with multimodal neuroimaging and brain stimulation, that prosody perception takes dual routes along dorsal and ventral pathways in the right hemisphere. In experiment 1, categorization of speech stimuli that gradually varied in their prosodic pitch contour (between statement and question) involved (1) an auditory ventral pathway along the superior temporal lobe and (2) auditory-motor dorsal pathways connecting posterior temporal and inferior frontal/premotor areas. In experiment 2, inhibitory stimulation of right premotor cortex as a key node of the dorsal stream decreased participants' performance in prosody categorization, arguing for a motor involvement in prosody perception. These data draw a dual-stream picture of prosodic processing that parallels the established left-hemispheric multi-stream architecture of language, but with relative rightward asymmetry.
我们的语调——韵律——对言语意义的贡献远不止于实际说出的词汇。事实上，一个语气迟疑的“是”可能比其肯定的词汇意义更能说明问题。人类大脑左半球包含背侧和腹侧加工流，这些加工流是诸如音系学、句法和语义学等核心语言能力的基础。韵律——据说是右半球的功能——是否涉及类似的加工流仍是一个有争议的问题。关于韵律的功能连接性研究无疑证明了这些加工流的存在，但对于信息是沿着背侧还是腹侧通路传递，观点存在分歧。在这里，我们通过一种结合音频变形、多模态神经成像和脑刺激的新范式表明，韵律感知在右半球沿着背侧和腹侧通路采取双重路径。在实验1中，对韵律音高轮廓（在陈述句和疑问句之间）逐渐变化的语音刺激进行分类涉及：（1）一条沿着颞上叶的听觉腹侧通路，以及（2）连接颞叶后部和额下/运动前区的听觉-运动背侧通路。在实验2中，作为背侧流关键节点的右运动前皮层受到抑制性刺激，降低了参与者在韵律分类中的表现，这表明运动参与了韵律感知。这些数据描绘了一幅韵律加工的双流图景，它与已确立的左半球语言多流结构相似，但相对向右不对称。
